TW201812362A - Plano-convex lens, fiber matrix module and light receiving module - Google Patents

Abstract

The purpose of the present disclosure is to achieve a reflection lens-optical fiber coupling system in which a part of light that has been split for use in a monitor and returned to an optical fiber is efficiently coupled in the optical fiber. The plano-convex lens according to the present disclosure is provided with a flat surface (21) and a convex surface (23), wherein: the convex surface (23) has a first aspherical surface (A1) and a second aspherical surface (A2) that convert, into parallel rays, light rays emitted from end faces of two optical fibers (11), the end faces being respectively disposed at a first position (P1) and a second position (P2); and in the case when the parallel rays entering the first aspherical surface (A1) are reflected on a reflection surface formed on the flat surface (21), the second aspherical surface (A2) focuses the parallel rays on the second position (P2).

Description

Plano-convex lens, fiber matrix module and light receiving module

The present invention relates to a plano-convex lens having an aspheric surface, and an optical fiber matrix module and a light receiving module having the same.

A light receiving module for WDM (Wavelength Division Multiplexing) transmission is proposed (for example, refer to Patent Document 1). The light-receiving module of Patent Document 1 uses a lens matrix to collimate a light beam emitted from the fiber matrix, and in order to monitor the light in the transmission path, a beam splitter is used to branch a part of the light beam, and a PD ( Photo Detector). The light receiving module of Patent Document 1 uses a beam splitter to reflect most of the light beam collimated by the lens matrix to the lens matrix, and returns to the fiber matrix. [Prior Art Literature] [Patent Literature] [Patent Literature 1] Japanese Patent Laid-Open No. 2009-093131 [Patent Literature 2] Japanese Patent Laid-Open No. 3-131803

[Problems to be Solved by the Invention] If the light beam that is miniaturized and collimated by the lens matrix is relatively thicker than the diameter of the lens, the effect of the lens aberration becomes significant, and it should be returned again after a partial branch is used for monitoring It is difficult to couple the light to the optical fiber with the optical fiber. Therefore, an object of the present invention is to efficiently couple the light which should be returned to the optical fiber again after the local branch is used for monitoring in the reflective lens-fiber coupling system. [Technical means to solve the problem] Specifically, the plano-convex lens of the present invention includes a flat surface and a convex surface, and the convex surface has a first aspheric surface and a second aspherical surface, and the first aspheric surface and the second aspherical surface system A case where the light emitted from the above-mentioned end faces of the two optical fibers whose end faces are arranged at the first position and the second position is parallel light, and the parallel light incident from the first aspheric surface is reflected by a reflecting surface formed on the flat surface At this time, the second aspheric surface condenses the parallel light at the second position. Specifically, the plano-convex lens of the present invention includes a flat surface and a convex surface, and the convex surface has a first aspherical surface and a second aspherical surface, and the first aspheric surface and the second aspherical surface are arranged from the end surface to the first The light incident from the above-mentioned end faces of the two optical fibers at the second and second positions to the flat surface is parallel light, and is focused on a reflecting surface disposed at a predetermined distance from the first position and the second position at a predetermined distance. When the parallel light emitted from the first aspheric surface is reflected at the one point, the second aspheric surface condenses the parallel light at the second position. In the plano-convex lens of the present invention, the first aspheric surface may have a first convex surface, and the first convex surface is at an intersection between the straight line passing through the first position and perpendicular to the reflective surface, and the convex surface, and the convex surface. There is a vertex between the centers, and the second aspheric surface has a second convex surface, and the second convex surface is between an intersection of a straight line passing through the second position and perpendicular to the reflective surface and the convex surface, and between the center of the convex surface vertex. In this case, it is preferable that the convex surface is provided between the first convex surface and the second convex surface, and further includes a saddle portion for reducing a change in shape of a boundary between the first convex surface and the second convex surface. In the plano-convex lens of the present invention, a reflecting portion may be provided on the reflecting surface, and the reflecting portion transmits a part of the parallel light incident from the first aspheric surface, and a part of the parallel light is directed toward the second aspheric surface. reflection. Specifically, the fiber matrix module of the present invention includes: a first lens matrix having a plurality of plano-convex lenses of the present invention, and the center axes of the plano-convex lenses are arranged side by side in a predetermined specific plane; and a fiber matrix, There are two optical fibers with respect to each of the plano-convex lenses, and an end face of each optical fiber is disposed at the first position or the second position of each of the plano-convex lenses. The optical fiber matrix module of the present invention may further include a GRIN lens matrix, the GRIN lens matrix having a plurality of GRIN lenses for each of the parallel light transmitted through the reflecting surface to enter one end of different GRIN lenses, and Each light emitted from the other end of the GRIN lens is condensed at a point specified by each of the GRIN lenses. The optical fiber matrix module of the present invention may also include: the optical fiber matrix module of the present invention; an optical component having a plurality of through holes for transmitting parallel light transmitted through the reflective surface for transmission from the reflective surface; Each of the parallel light is incident on one end of a different through-hole, and the parallel light that passes through the through-hole is emitted from the other end of each through-hole; and a second lens matrix, which will pass from the other end of the plurality of through-holes Each emitted light is condensed at a point prescribed by each of the above-mentioned through holes. Specifically, the light receiving module of the present invention includes the optical fiber matrix module of the present invention and a light receiving element matrix. [Effects of the Invention] According to the present invention, in a reflective lens-fiber coupling system, light that should be returned to the optical fiber after being partially branched for monitoring can be efficiently coupled with the optical fiber.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. These examples are merely examples, and the present invention can be implemented in the form of various changes and improvements based on the knowledge of the practitioner. It should be noted that constituent elements having the same reference numerals in this specification and the drawings indicate those that are the same as each other. (First Embodiment) Fig. 1 shows an optical system according to this embodiment. In this embodiment, optical fibers 11A and 11B are arranged on the convex surface 23 side of the plano-convex lens, and a partially reflecting portion 4 is arranged on the flat surface 21 side of the plano-convex lens. The end faces of the optical fibers 11A and 11B are arranged at a first position P1 and a second position P2, respectively. The length direction of the optical fibers 11A and 11B is on a specific plane P_C Center axis A of internal and plano-convex lenses_C Parallel configuration. The plano-convex lens of this embodiment has a first aspherical surface A1 and a second aspherical surface A2 on the convex surface 23. The light emitted from the end surface P1 of the optical fiber 11A is incident on the plano-convex lens from the first aspherical surface A1. The first aspherical surface A1 makes the light emitted from the end surface P1 of the optical fiber 11A parallel light. The light that becomes parallel light by the first aspheric surface A1 passes through the plano-convex lens, and a part of the reflecting portion 4 disposed on the flat surface 21 reflects a portion toward the second aspheric surface A2. The second aspherical surface A2 condenses the parallel light reflected by the partial reflection portion 4 to the second position P2. Thereby, the parallel light reflected by the partial reflection portion 4 is incident on the optical fiber 11B. In the plano-convex lens of this embodiment, since the second aspherical surface A2 condenses the parallel light reflected by the partial reflection portion 4 to the second position P2, it is possible to branch the monitoring light locally (hereinafter referred to as a tap) and the optical fiber 11B is well coupled. (Second Embodiment) FIG. 2 shows a configuration example of an optical fiber matrix module according to this embodiment. The optical fiber matrix module of this embodiment includes: a lens matrix 2 in which a plurality of convex surfaces 23-1 to 23-4 are arrayed in the first embodiment; and an optical fiber in which a plurality of optical fibers 11A and 11B are aligned in the first embodiment. Matrix 1. The optical fiber matrix 1 and the lens matrix 2 indicate that the four optical fiber-lens optical systems of the first embodiment are arranged side by side on a specific plane P_C The example above. The lens matrix 2 functions as a first lens matrix. The lens matrix 2 includes a plurality of plano-convex lenses according to the first embodiment. Each of the plano-convex lenses included in the lens matrix 2 includes the optical fiber-lens optical system of the first embodiment as a basic unit. Optical axis A is the central axis of each plano-convex lens_C Arranged side by side on a specific plane P_C Inside. The optical fiber matrix 1 has two optical fibers 11A and 11B for each of the convex surfaces 23-1 to 23-4. The optical system of FIGS. 1 and 2 will be described with reference to FIG. 3. The following directions are described following the orthogonal xyz coordinate axes in the figure. On the left side of the figure, it is arranged in the xz plane in parallel with the z axis in the x axis direction at equal intervals d_f An optical fiber matrix 1 in which optical fibers are arranged. The optical fiber matrix 1 has a plane that is parallel to the x-axis and has a specific angle with respect to the y-axis as an end surface, and is configured, for example, by being held by a casing such as TEMPAX glass. Has an optical axis A parallel to the z-axis_C Convex surface 23 will be perpendicular to the optical axis A_C That is, the plane of the z-axis is set as a common plane, and is spaced 2d in the x-axis direction at twice the interval of the fiber matrix 1._f Matrix. The convex side of the lens matrix 2 is disposed toward the optical fiber matrix 1 with an air layer 3 at a specific distance described below. As shown in the figure, the thickness of the lens matrix 2 is the distance between the convex surface 23 and the flat surface 21 on the opposite side and the concave focal length f._c Set in a consistent manner. The relative position of the fiber matrix 1 and the lens matrix 2 is set as follows: in the x-axis direction, the optical axis A of the plano-convex lens_C The center lines of the adjacent fibers of the optical fiber matrix 1 (the center lines of the first optical fiber 11A and the second optical fiber 11B in the figure) are the same, and in the y direction, the optical axis A of the lens_C The plane formed by the matrix is consistent with the plane formed by the centerline of the fiber matrix, and in the z direction, the distance between the end face of the fiber matrix 1 and the convex vertex of the lens matrix 2 and the convex side focal length f of the plano-convex lens_v Consistent. A partial transmission film 41 having a function of reflecting / transmitting light of a specific wavelength at a desired ratio may be applied to the side surface of the flat surface 21 of the lens matrix 2. Spacers 22 are provided at both ends of the lens matrix 2 to maintain the distance between the lens matrix and the optical fiber matrix 1 at a specific value. The spacer 22 may be formed in advance with a concave portion corresponding to the lens in a mold simultaneously with forming the concave portion corresponding to the lens, and then formed by a molding method simultaneously with forming the lens, or may be in the form of sandwiching a plate of a specific thickness. In addition, in this configuration, the path of light emitted from the end face of the first optical fiber 11A is approximately studied with light rays. Since the end face of the first optical fiber 11A is located on the convex side focal plane, the light emitted from the end face of the first optical fiber 11A as a point light source and incident on the corresponding lens of the lens matrix 2 is directed toward the optical axis A._C Side refraction and becomes with the optical axis A_C At an angleThe parallel rays of light travel through the lens. Among them, the ends of the optical fibers 11A and 11B and the optical axis A_C That is, the light rays emitted in parallel with the z-axis, that is, the central light rays of the parallel light, enter the plano-convex lens and pass through the focal point on the concave side. As mentioned above, the thickness of the plano-convex lens is set exactly to the concave focal length f_c And the part becomes a flat surface, and a part of the transmissive film 41 is applied to the part. Therefore, a part of the specific intensity of the parallel light is transmitted through the part of the transmissive film 41 and relative to the optical axis A_C forThe angle is straight, but the remaining intensity is partially reflected by the partially transmitting film 41 and is relative to the optical axis A._C The symmetrical x-direction position reaches the plano-convex lens surface again. The reflected light that has reached the surface of the lens is parallel light that passes through the focal point on the concave side, along the optical path that exits from the first optical fiber 11A and enters the plano-convex lens with respect to the optical axis A_C Symmetric path, finally focused to a position relative to the optical axis A_C An end face P2 of the second optical fiber 11B at a position symmetrical to the first optical fiber 11A. Here, if the thickness of the plano-convex lens is set to the focal length f of the concave side,_c Thin, the reflected parallel light is f compared to the lens thickness_c Optical axis A_C The side surface is here where the parallel light is not bundled and further diffuses on the end face of the second optical fiber 11B. On the other hand, the lens thickness is thicker than f_c In this case, the reflected light further reaches the outer surface of the lens, so the parallel light is excessively collected, and as a result, it diffuses on the end face of the second optical fiber 11B. In either case, the optical axis of the reflected light is offset from the optical axis of the second optical fiber 11B. The distance between the end faces of the optical fibers 11A and 11B and the lens matrix 2 is preferably set to the convex side focal length f_v Meanwhile, the flat surface 21 of the lens matrix 2 is a concave focal surface. In addition, the light transmitted through the part of the transmissive film 41 is shown in FIG. 3._v If it is the same, it shoots out at an angle ψ. Although not shown, if the refractive index of the adjacent medium is the same as the refractive index of the lens matrix 2,Shoot out. In addition, when a low-loss coupling is desired between the optical fibers 11A and 11B with such a reflection optical system, the surface shape required for the convex surface 23 is generally called an aspheric surface. The aspheric shape differs depending on the setting form of the optical system, and the method for obtaining the aspheric shape in this embodiment will be described with reference to FIG. 4. In FIG. 4, for convenience of description, light is described as being emitted from the second optical fiber 11B. However, since the optical system is symmetrical with respect to the optical axis, the authenticity is not impaired. As shown in the figure, the setting includes the optical axis A_C The xz plane, and the lens curved surface as the rotation curved surface with the z axis as the axis of symmetry, and the shape of the xz section as Z (x). The optical system set here is a model in which the second quadrant in the xz plane is placed parallel to the z-axis and placed on the convex side focal distance f from the x-axis._v The light emitted from the second optical fiber 11B at an upward position at an angle of θ is refracted at an intersection with the hypothetical curve Z (x), and reflected at the reflection angle illustrated in FIG. 3Travel in the lens. According to Snell's law of the refracting position, the following equation holds, that is, (Equation 1). Here, n_v , N_c , Θ_v , Θ_c The refractive index of the air layer 3, the refractive index of the plano-convex lens, the incident angle to the lens surface, and the exit angle from the lens surface, respectively. If the angle formed by the tangent to the curve Z (x) of the light incident position and the x-axis is set to θ_t , According to the angular relationship in FIG. 4, it is easy to know that there is a relationship of the following formula, that is, (Equation 2). The following formula is established based on the formulas (1) and (2). (Equation 3)Here, because the angle θ_t The tangent angle of the curve Z (x), so the following formula holds. [Equation 4]In addition, the outgoing light from the optical fiber 11B and the optical axis A_C The tangent of the formed angle θ satisfies the following formula, that is, (Equation 5). By changing θ of equation (4)_t Substituting θ with Equation (5) into Equation (3), a differential equation related to Z (x) can be obtained. The curve is obtained according to the boundary conditions of equations (3) to (5) and the origin (0, 0) expressed by the following equation, but it becomes a complex nonlinear differential equation that cannot be solved analytically, and is approximately calculated Find it out. At this time, since it may be solved analytically, the function form is determined based on this in advance. [Equation 6]The situation that can be solved analytically is the position of the x-direction of the second optical fiber 11B and the optical axis A of the lens in FIG. 4_C Consistent situation (d_f / 2 = 0). At this time, the reflection angle in FIG. 4It becomes zero, Z (x) is calculated | required analytically, and it becomes a hyperbola of Formula (7). [Equation 7]Here, C_h Is a curvature, and is the following formula, that is, (Equation 8), K_h Is a conic constant, and is the following formula, that is, (Equation 9). As in this embodiment, the optical fibers 11A and 11B are from the optical axis A._C In the case of a shift, it is assumed that Equation (7) is used as the basic equation and an approximate term based on the polynomial shown below is added. [Equation 10]Here, n is an integer of 2 or more, A₃ , A₄ , ... A_{2n - 1} , A_2n Aspheric coefficient. After determining the number of times corresponding to the target accuracy in equation (10), substitute equations (3), (4), and (5) to calculate the residual error, and find the curvature C that is the global solution according to the damping least square method._h Cone constant K_h , And aspheric coefficient A_{2n - 1} , A_2n Combination. If the coefficient value in formula (10) is specified, the surface shape can be processed in the mold. The coefficients to be specified can be determined by equations (3) to (5). Even without such calculations, the possibility can be verified. First, the names and symbols of the parameters shown in FIGS. 3 and 4 are shown in the left column of FIG. 5. In FIGS. 3 and 4, the light emitted from the first optical fiber 11A having the end surface on the convex side focal surface and entering the convex surface 23 through the air layer 3 becomes the optical axis A_C PresentAngle of parallel light. Therefore, for these rays to enter the lens optical axis A_C The light rays at the intersection with the lens surface (that is, the apex of the convex surface 23 of the lens), because the tangent plane of the lens surface is exactly perpendicular to the optical axis A_C The parallel z-axis, so the incident angle ψ and the exit angle of the lens center of the lightWith refractive index n_v , N_c In the meantime, Snell's law holds, that is, (Equation 11). Since the fiber matrix 1_f Matrixed and lens matrix 2 is 2d twice_f Matrixization, so if the fiber spacing d is given_f Incident angle ψ and exit angle from lens centerValue, the focal length f on each of the convex and concave sides_v , F_c It is determined by the following formulas (12) and (13). (Equation 12)(Equation 13)In the above formulas (11) to (13), no approximate operation is added and the formula is strict, and the optical axis A that satisfies this relationship is_C The rotation surface that is the axis of symmetry becomes a higher-order surface based on the rotation hyperbola. Determine the two focal lengths f of the convexo-concave of the plano-convex lens according to equations (12) and (13)_v , F_c That is, the distance between the optical fibers 11A and 11B and the plano-convex lens and the lens thickness are determined. Second, the limiting factors of this optical system are described. The emitted light from the first optical fiber 11A is diffused according to NA (Numerical Aperture) of the optical fiber, but it is clear from FIG. 3 that the beam diameter BD must be such that the distance f_v The adjacent lens is not touched everywhere, so the following condition must be satisfied, that is, (Equation 14). There are also restrictions on the surface shape of the convex surface 23. The lens matrix 2 having the convex surface 23 is produced by a molding method using a mold, but at this time, the curvature radius of the concave shape grinding process is limited, and is generally set to 150 μm or more. The shape of the lens surface is aspheric, and its radius of curvature is as the optical axis A_C The lens center is the smallest and moves away from the optical axis A_C And gradually increased. Therefore, it is the minimum radius of curvature that is a problem when manufacturing a mold, but since it is the smallest at the center of the lens, if it is estimated by a spherical approximation, it becomes the following formula (15). [Equation 15]Here, for clarity, the convex side focal length f is added._v With concave focal length f_c The spherical approximation is given by the following formula. [Equation 16][Equation 17]In addition, an attempt is made to substitute equations (11) to (15) into actual possible values and calculate a value below the lens central incident angle ψ in FIG. 3 as an example of the estimation in FIG. 5. Fiber spacing d_f Choose the commonly used values of 250 μm and 127 μm. The refractive index of the lens is 1.501. The refractive index of the glass with high weather resistance is 1.501. Second, the reflection angleIn the present embodiment, an optical tap module with a so-called tap film having an optical fiber pair consisting of the optical fiber 11A and the second optical fiber 11B as the main optical path and a part of the transmissive film 41 reflecting 90% or more and transmitting a few% is considered The application is set to an angle of 5 degrees that does not produce polarization dependence on partially transmitted light. At fiber spacing d_f For 250 μm and 127 μm, the convex focal length f_v They are 947.3 μm and 481.2 μm, respectively. At this time, the diameter BD of the light beams emitted from the optical fiber 11A on the lens surface becomes smaller than the fiber interval d, respectively._f 227.4 μm, 115.5 μm, so this light does not touch the adjacent lens. Here, as the NA of the optical fibers 11A and 11B, a standard single-mode optical fiber having a mode diameter of 9.0 / 10.0 μm in the 1.3 / 1.55 μm band is selected as 0.12. In addition, since the optical axis A of the surface of the convex surface 23 of the lens matrix 2_C The approximate radii of curvature of the upper spheres are 474.6 μm and 241.1 μm, so they fully exceed the mechanical processing limit of the mold, which is 150 μm, and can be used for mold lens processing. Although it is a partially transmissive film 41, it is usually formed by alternating multilayer laminated films using silicon dioxide as a low refractive index film material and titanium dioxide or tantalum pentoxide as a high refractive index film material. As the substrate at this time, the lens matrix 2 is a good substrate because the flat surface 21 facing the convex surface 23 is the same oxide-based material. In short, it can be seen that the configurations of FIGS. 1, 2, and 3 can be realized. (Third Embodiment) Fig. 6 is a perspective view of an optical system according to this embodiment. The plano-convex lens 2 of this embodiment is a bi-modal bi-modal lens in which the first aspherical surface A1 and the second aspherical surface A2 are convex in the first embodiment and the second embodiment. In the third embodiment and the fourth embodiment, the first aspherical surface A1 is referred to as a first convex surface A1, and the second aspherical surface A2 is referred to as a second convex surface A2. The plano-convex lens 2 of this embodiment is a flat substrate made of lens material having a rectangular shape parallel to the axis of the xyz orthogonal coordinate in the figure, and has a convex surface 23 including three curved surfaces. The first is a first convex surface A1 composed of a curved surface having a straight line R1 parallel to the z-axis as a center line and an intersection point with R1 as a peak P6. The second is a second convex surface A2 which is formed by a curved surface having a straight line R2 parallel to the z-axis as a center line and an intersection point with R2 as a peak P8. The second convex surface A2 moves the first convex surface A1 in parallel in the x direction by a peak interval d._p The resulting shape. In the figure, the rotation center line of the second convex surface A2 is represented by R2. The diameters of the two convex surfaces A1 and A2 series lenses that function as a lens are set to a peak interval d_p Large and arranged so as to overlap each other. The overlapping part is cut out as shown in the figure, and a third surface, that is, the width w is connected to the convex surface of A1 and A2 at this part._s Saddle A3. According to the contour line indicated by the dotted line in the figure, it can be seen that the saddle portion A3 also protrudes from the surrounding plane and smoothly connects the two convex surfaces A1 and A2. As a whole, the plano-convex lens 2 passes through the midpoint of two peaks formed by the convex surfaces A1 and A2, and uses a straight line Ac parallel to the z-axis as the lens centerline. Hereinafter, a straight line passing through the peaks of the convex surfaces A1 and A2 and parallel to the x-axis is referred to as a peak line Bc. The linear first optical fiber 11A having an optical axis parallel to the z-axis is disposed with respect to the bimodal lens such that its optical axis intersects the peak line Bc outside the specified distance from the center line R1 of the convex surface A1, and is from The light emitted from an optical fiber 11A is shifted and incident at the intersection point P4 which is further outside than the peak P6 of the convex surface of the first lens. The intersection point P4 is an intersection point between the straight line passing through the first position P1 and perpendicular to the flat surface 21 and the convex surface 23. A specific amount of intensity of the incident light is reflected by the following mechanism, and is condensed from the intersection point P7, which is more outward than the peak P8 of the convex surface of the second lens, and is incident on the first optical fiber 11A symmetrically disposed with respect to the lens centerline Ac. Two optical fibers 11B. The intersection point P7 is an intersection point of the straight line passing through the second position P2 and perpendicular to the flat surface 21 and the convex surface 23. A bimodal lens can be produced by a glass molding method using a mold. FIG. 7 shows a contour map obtained when the mold is viewed from the z-axis direction in the mold manufacturing step. First, as shown in FIG. 7, concave surfaces corresponding to the first and second convex surfaces A1 and A2 are formed on the mold surface. If there is a ridgeline at the boundary, there is a possibility that the movement of substances during the molding operation may be hindered. Therefore, as shown in FIG. 8, the boundary is cut in such a way that it does not reach the projection light intensity distribution pattern from the optical fiber on the projection portion Pd on the xy plane, and the shape change at the boundary is eased. Thereby, it becomes the shape provided with the saddle part A3 as shown in FIG. Next, in order to more easily explain the optical system of this embodiment, FIG. 9 is used as a cross-sectional view obtained by cutting the plane including the rotation center lines R1 and R2. In this embodiment, optical fibers 11A and 11B are arranged on the convex surface 23 side of the plano-convex lens 2, and a partially reflecting portion 4 is arranged on the flat surface 21 side of the plano-convex lens 2. The end faces of the optical fibers 11A and 11B are arranged at a first position P1 and a second position P2, respectively. The length direction of the optical fibers 11A and 11B is on a specific plane P_C Center axis A of inner and bimodal lenses_C Parallel configuration. Hereinafter, this embodiment is referred to as type I. The plano-convex lens 2 of this embodiment has two convex surfaces on the convex surface 23. The first convex surface A1 is a rotating curved surface that is parallel to the center axis Ac of the plano-convex lens and is included in the straight line R1 of the plane Pc formed by the optical fibers 11A and 11B. The second convex surface A2 is also similar to the center axis of the plano-convex lens. Ac is a rotation curved surface parallel to the straight line R2 included in the plane Pc formed by the optical fibers 11A and 11B. The rotation center lines R1 and R2 are symmetrical with respect to the central axis Ac, and are offset inward relative to the two fiber centerlines. distance. (Fourth Embodiment) Fig. 10 shows a configuration example of an optical fiber matrix module according to this embodiment. The optical fiber matrix module of the present embodiment is the optical fiber matrix module of the second embodiment, and the plano-convex lens 2 of the third embodiment is applied to the convex surfaces 23-1 to 23-4. The optical system in FIGS. 9 and 10 will be described with reference to FIG. 11. On the left side of the figure, a periodic interval d is arranged in the xz plane parallel to the z axis in the x axis direction._f An optical fiber matrix 1 in which optical fibers are arranged. The optical fiber matrix 1 has a plane that is parallel to the x-axis and has a specific angle with respect to the y-axis as an end surface, and is configured, for example, by being held by a casing such as TEMPAX glass. The first convex surface A1 is a curved surface that is centered on a line R1 that is included in a surface Pc formed by the fiber matrix and is parallel to the z-axis, and functions as a lens. Further, the optical axis of the optical fiber 11A is shifted toward the inside (on the center axis Ac side) by a certain distance. The second convex surface A2 is formed with a width w with respect to the lens central axis Ac._s The saddle is symmetrical to the first convex surface A1. The interval d between the centerlines of rotation R1 and R2 of the first and second convex surfaces A1 and A2, respectively_p (Hereinafter referred to as peak interval d_p ) Set to less than the fiber spacing d_f Distance. The convex side of the lens matrix 2 faces the optical fiber matrix 1 through the thickness and the convex side focal length f_v Equivalent air layer 3 is arranged. As shown in the figure, the thickness of the lens matrix 2 is the distance between the bimodal convex surface 23 and the flat surface 21 on the opposite side, but it is set to be thicker than the concave focal length f._c Lens thickness t₁ . The relative position of the fiber matrix 1 and the lens matrix 2 is set in such a manner that, in the x-axis direction, the center axis A of the bimodal lens_C The center lines of the adjacent fibers of the optical fiber matrix 1 (the center lines of the first optical fiber 11A and the second optical fiber 11B in the figure) are the same, and in the y direction, the central axis A of the lens_C The plane formed by the matrix is consistent with the plane formed by the centerline of the fiber matrix, and in the z direction, as described above, the distance between the end face of the fiber matrix 1 and the convex vertex of the lens matrix 2 and the convex side focal length f of the bimodal lens_v Consistent. In such a configuration, the path of light emitted from the end face of the first optical fiber 11A is examined by approximating the light. Since the end face of the first optical fiber 11A is located on the convex side focal plane, and the centerline R1 of the first convex surface A1 in the bimodal convex surface is shifted in the x direction relative to the fiber centerline as described above, The end face is a point light source, and the light that exits from it and enters the first convex surface A1 of the lens matrix 2 is directed toward the central axis A_C Side refraction, with the central axis A_C At a specific angleThe parallel rays of light travel through the lens. Among them, the end of the optical fiber 11A and the central axis A_C That is, the light rays emitted in parallel with the z-axis, that is, the central light rays, enter the plano-convex lens and pass through the focal point of the concave side. If set to the thickness t of the plano-convex lens as described above₁ Thicker than the concave focal length f_c And the flat surface 21 is located at the above-mentioned central ray and the lens central axis A_c At the point of intersection, and a part of the transmissive film 41 is applied to the flat surface 21, a part of the specific intensity of the parallel light is partially transmitted through the film 41 and relative to the central axis A_C Straight forward at an angle of ψ, but the rest of the intensity is reflected by the partially transmitting film 41, relative to the central axis A_C The symmetrical x-direction position reaches the second convex surface A2. The reflected light that reaches the second convex surface A2 is parallel light that passes through the focal point of the concave side, and is along the optical path that exits from the first optical fiber 11A and enters the bimodal lens with respect to the central axis A._C Symmetric path, finally focused to A relative to the central axis A_C An end face P2 of the second optical fiber 11B at a position symmetrical to the first optical fiber 11A. Next, the above description is formulated using a formula. In FIG. 11, the light emitted from the first optical fiber 11A having the end surface on the convex side focal surface and entering the first convex surface A1 of the convex surface 23 through the air layer 3 becomes the center axis A of the lens._C PresentAngle of parallel light. Among these rays, the rays incident on the peak of the first convex surface A1 (the intersection point of the central symmetry line R1 and the first convex surface), because the tangent plane of the lens surface of the incident point is perpendicular to the central axis A_C , So the incident angle ψ and the exit angle at the center of the peak of the lightAnd refractive index n_v , N_c In between, Snell's law holds. (Equation 31)Here, n_v , N_c Respectively the refractive index of the air and the refractive index of the lens. In addition, since the fiber matrix 1 is spaced at periodic intervals d_f Matrix, and the lens matrix 2 is 2d with a period twice_f Matrix, so focal length f on each side of convex side and concave side_v , F_c Based on fiber spacing d_f Peak interval d between the first convex surface A1 and the second convex surface A2_p , Lens center incident angle ψ, and exit angleThe value is determined by the following equations (32) and (33). (Equation 32)(Equation 33)About lens thickness t₁ Similarly, the following equation holds, (Equation 34). Furthermore, the radius of curvature at the peaks of the convex surfaces A1 and A2 is the peak radius of curvature R_p Is given by: (Equation 35). The first and second convex surfaces A1 and A2 constituting the double peak may satisfy the above-mentioned formulas (31) to (35), but satisfy these relationships and be parallel to the lens central axis A._C The rotating surface whose axis is the axis of symmetry becomes a higher-order surface based on a rotating hyperbola, which is generally called an aspheric surface. If fiber spacing d is given_f Peak interval of lens d_p Lens refractive index n_c Refractive index n_v , And reflection angle, The two focal lengths f of the convexo-concave of the bimodal lens are determined based on equations (32) and (33)_v , F_c That is, the distance between the optical fibers 11A and 11B and the bimodal lens is determined, and the lens thickness t is determined based on equation (34).₁ . In addition, it is known from the formula (35) that the peak radius of curvature is a standard for the shape of the mold used in the molding step of the lens production step. Next, the conditions for establishing such an optical system will be described. In order to achieve the low-loss coupling between the first optical fiber 11A and the second optical fiber 11B, it is necessary to suppress the shading of the lens surface as much as possible. The outgoing light from the first optical fiber 11A is diffused according to the NA of the optical fiber, but the diffusion often manifests as the transmission of a Gaussian beam with the fiber end as the waist position of the beam. The power of the Gaussian beam exiting from the fiber end and reaching the lens surface is distributed from the center of the beam to 1.73 times the beam radius ω to become 99.75% of the total power. Therefore, if the range up to this point is the beam diameter BD of the light beam reaching the lens surface, that is, the convex surface 23, it is given by the following formula. [Equation 36]Here, ω₀ And λ are the mode radius of the optical fiber 11A and the wavelength of light, respectively. Next, based on the configuration of the lens, the conditions required for the beam diameter BD on the lens surface were studied in accordance with FIG. 12. In the bimodal lens of this embodiment, if the peak interval d is increased,_p Then, as shown in FIG. 12 (a), the overlap of the convex surfaces of the two lenses is eliminated, and the two convex surfaces are in a state. That is, the saddle curved surface A3 becomes the same plane as the plane around the lens. This is referred to as a two-plate state, and a comparison between this and a bimodal state is performed. First, a two-chip system will be studied based on FIG. 12 (a). In a two-chip system, in order to achieve a light-shielding, low-loss fiber-to-fiber coupling, the distance x in the x-axis direction between the centerline of the fiber parallel to the z-axis and the outer edge of the lens near the centerline side_E Must be larger than half of the beam diameter BD of the light emitted from the optical fiber on the lens surface, so the following must be true. (Equation 37)I.e. (Equation 38)Here, BD represents the beam diameter of the light emitted from the optical fiber on the lens surface, and d_p Represents the peak interval between convex A1 and convex A2, d_f Represents the distance between optical fibers, w_s Indicates the width of the saddle A3. This is a 2 piece condition. Following, will 2d_p -D_f -W_s Called the 2-chip condition index. If the conditions shown in formula (38) are opposite and the beam diameter BD on the lens is greater than two conditions index, in order to form an optical system without light blocking, a bimodal configuration must be used. On the other hand, in the two-peak system shown in Fig. 12 (b), the condition of no shading is shown in Fig. 12 (b). The distance D between the center line of the fiber and the two ends of the outer edge of the lens in the x-axis direction is D._C , D_E Both must be larger than one and a half of the beam diameter BD, so the following equation must hold, that is, (Equation 39). This condition becomes a broader condition including the condition of formula (38) as described below. Here, a case where the bimodal shape is unnecessary may be described in advance. In the example of FIG. 12, the beam area on the lens surface is across both sides of the lens peak, but also consider the case where the beam area is only distributed outside the lens peak as shown in FIG. 13 (a). This case corresponds to a case where the beam diameter BD on the lens surface is sufficiently small to satisfy the conditions of Expressions (38) and (39) and also satisfy the following expression. (Equation 40)In this case, the shape of the lens does not need to be doublet, but may be a ladder shape as shown in the contour map of FIG. 13 (b) or FIG. Sex is also higher. Then there is another condition. It is related to the peak curvature radius R when making the mold_p relevant person. (Equation 41)The reason is as follows. The target plano-convex lens in this embodiment is produced by a molding method. The method is a method in which a concave hole formed in a mold is pressed on a raw glass to transfer the concave shape into a convex shape of the glass. The curvature radius of the curved surface of the lens depends on the curvature radius of the hole that can be achieved by a machine tool for making the mold. It is set to 150 μm or more. That is, it means that a depth with a smaller radius of curvature below this cannot be formed. Next, the above-mentioned contents are shown in the graphs shown in FIG. 15 and FIG. 16 to describe the conditions under which the type I optical system can be constructed. First, the numerical values used in the calculation will be explained. Fiber spacing d_f : As the fiber periodic interval often used in fiber matrix 1, 250 μm with a general 250 μm pitch ribbon fiber is used in FIG. 15, and 127 μm, which is matrixed as an upper and lower nest, is used in FIG. 16. Wavelength λ: 1.55 μm, which is the representative value of the optical communication band. Mode radius ω₀ : Set to 5.2 μm as the representative value of single-mode fiber at a wavelength of 1.55 μm. Lens refractive index n_c : The refractive index distribution of the optical glass used for the lens is 1.4 from the crown glass on the low refractive index side to 2.0 on the flint glass on the high refractive index side. Therefore, consider the lens refractive index n here_c It is 1.4 to 2.0. Air refractive index n_v : Since the outside of the lens is usually air, it is set to 1.0. Saddle A3 width w_s Distance from adjacency_n : When the lens is manufactured by the glass molding method, a lens-shaped hole is excavated from the mold. In experience, a flat portion of about 10 to 20 μm is required between adjacent holes. The reason is that if the width is narrower than this, sharp protrusions with a narrow width will be generated between adjacent holes, which will cause deformation at the high temperature and high pressure (1 MPa, 450 ° C or higher) in the molding step, which will cause damage. As the durability of the mold. Therefore, here, the width w of the saddle A3_s Adjacency interval d_n Both are set to 17 μm. Reflection angle: It is assumed that a dielectric multilayer film having an optical thickness of λ / 4 and a low-refractive-index transparent material and a high-refractive-index transparent material is alternately laminated for a part of the transmissive film 41. Structurally, the multilayer film is incident obliquely. Therefore, what is problematic is the polarization dependence of the transmitted tap light. For the use of SiO₂ (Refractive index 1.44) as a low refractive index material and using Ta₂ O₅ (Refractive index 2.12) In the case of a high refractive index material, theoretically, in order to set the polarization dependence of the tap light transmitted in the C + L band (wavelength 1530 to 1625 nm) to 0.05 dB or less, the reflection must be set. angleSet it to 4 degrees or less. Therefore, here, the reflection angle is also considered in consideration of the influence caused by changes in the refractive index or film thickness during actual production.Set to 2 degrees. Figure 15 shows the fiber spacing d in the type I configuration._f In the case of 250 μm, for each peak interval d_p Refractive index n_c With peak curvature radius R_p The relationship is obtained by plotting the graph. According to equations (31) to (35), for each peak interval, as the refractive index of the lens increases, the refractive power of the light increases, so the peak curvature radius increases. Regarding the peak interval, as the light increases toward the center of the peak, the radius of curvature is reduced in order to maintain the same refractive power. In this graph, the three-dotted line in the graph is applied to the two-peak condition, the two-piece condition, and the mold processing condition. The two-piece condition is specified by the formula (38), the bimodal condition of the present invention is specified by the formula (39), and the mold processing conditions are specified by the formula (41). Below the value obtained based on the two-piece condition, n is an optical system that can form a two-piece optical system without shading._c -R_p region. Below the value obtained based on the bimodal condition is the n of the optical system that can form a bimodal morphology without shading_c -R_p region. Higher than the value obtained according to the processing conditions of the mold, it becomes a formable n._c -R_p region. It can be seen that the area obtained according to the two-peak condition and the mold processing conditions is wider than the area obtained according to the two-piece conditions and the mold processing conditions, and the design freedom is relaxed to more than twice. In particular, under bimodal conditions, an optical system with a larger radius of curvature can be constructed, which means that the difficulty of mold processing is lower. Figure 16 shows the fiber spacing d in the type I configuration._f In the case of 127 μm narrower than that in FIG. 15, for each peak interval d_p Refractive index n_c With peak curvature radius R_p The relationship is obtained by plotting the graph. As in FIG. 15, for each peak interval, as the refractive index of the lens increases, the refractive power of the light increases, so that the peak curvature radius increases. Regarding the peak interval, as the light increases toward the center of the peak, the radius of curvature is reduced in order to maintain the same refractive power. In this graph, similar to FIG. 15, the three dotted lines in the graph are those in which the two-peak condition, the two-piece condition, and the mold processing condition are applied. It can be seen at a glance that the area where the bimodal morphology can be achieved is definitely wider than the two-chip morphology. If distance from fiber d_f = 250 μm, as the fiber spacing d_f Narrow and achievable n_c -R_p The area is also narrowed. The area where the bimodal shape can be realized becomes a triangular area surrounded by the dotted line of the bimodal condition and the mold processing condition._c It cannot be configured when it is 1.44 or less. However, when the refractive index of BK7, which is the representative of borosilicate glass with higher reliability, is 1.501, although the peak interval d_p It has a narrow width of 91.7 to 95.6 μm, but it can constitute an optical system, and it can be seen that the bimodal shape can cope with miniaturization. On the other hand, as for the two-chip condition, only n_c It is realized in an extremely limited area of 1.81 or more and a peak interval of 105 to 107 μm. This high-refractive-index region is a region that causes problems such as the occurrence of yellowing in terms of reliability. It has to be said that the practical applicability is low, and it can be considered as d_f At 127 μm, a two-piece configuration cannot be applied. (Fifth Embodiment) Fig. 17 shows an optical system according to this embodiment. In this embodiment, the optical fibers 11A and 11B are arranged on the flat surface 21 side of the plano-convex lens, and the partially reflecting portion 4 is arranged on the convex surface 23 side of the plano-convex lens. The end faces of the optical fibers 11A and 11B are arranged at a first position P1 and a second position P2, respectively. The length direction of the optical fibers 11A and 11B is on a specific plane P_C Center axis A of internal and plano-convex lenses_C Parallel configuration. The plano-convex lens of this embodiment has a first aspherical surface A1 and a second aspherical surface A2 on the convex surface 23. The light emitted from the end surface of the optical fiber 11A enters the plano-convex lens from the flat surface 21. The light incident on the plano-convex lens passes through the plano-convex lens and exits from the first aspheric surface A1 into the air layer 3. At this time, the first aspherical surface A1 makes the light emitted into the air layer 3 be parallel light. The light that becomes parallel light on the first aspherical surface A1 passes through the air layer 3 and is partially reflected toward the second aspheric surface A2 at one point P3 of the reflecting surface that partially transmits the film 41. The parallel light reflected by the partial reflection portion 4 enters the plano-convex lens from the second aspherical surface A2. The second aspherical surface A2 condenses the parallel light reflected by the partial reflection portion 4 to the second position P2. Thereby, the parallel light reflected by the partial reflection portion 4 is incident on the optical fiber 11B. In the plano-convex lens of this embodiment, the second aspherical surface A2 condenses the parallel light reflected by the partial reflection portion 4 to the second position P2, so that the light after tapping the monitoring light can be efficiently coupled with the optical fiber 11B. (Sixth Embodiment) FIG. 18 shows a configuration example of an optical fiber matrix module according to this embodiment. The optical fiber matrix module of this embodiment includes: a lens matrix 2 in which a plurality of convex surfaces 23-1 to 23-4 are arranged in a fifth embodiment; and an optical fiber in which a plurality of optical fibers 11A and 11B are arranged in a fifth embodiment. Matrix 1. The optical fiber matrix 1 and the lens matrix 2 indicate that the four optical fiber-lens optical systems of the fifth embodiment are arranged side by side on a specific plane P_C The example above. The lens matrix 2 functions as a first lens matrix. The lens matrix 2 includes a plurality of plano-convex lenses according to the fifth embodiment. Each of the plano-convex lenses included in the lens matrix 2 includes a fiber-lens optical system according to the fifth embodiment as a basic unit. Optical axis A is the central axis of each plano-convex lens_C Arranged side by side on a specific plane P_C Inside. The optical fiber matrix 1 has two optical fibers 11A and 11B for each of the convex surfaces 23-1 to 23-4. Spacers 22 are provided at both ends of the lens matrix 2 to maintain the distance between the lens matrix and the partial transmission portion 4 at a specific value. The spacer 22 may be formed in advance with a concave portion corresponding to the lens in a mold simultaneously with forming the concave portion corresponding to the lens, and then formed by a molding method simultaneously with forming the lens, or may be in the form of sandwiching a plate of a specific thickness. The optical system of FIGS. 17 and 18 will be described with reference to FIG. 19. The following directions are described following the orthogonal xyz coordinate axes in the figure. At the left end of the figure, it is arranged in the xz plane parallel to the z axis in the x axis direction at equal intervals d_f Arrayed fiber matrix 1. The optical fiber matrix 1 has a plane that is parallel to the x-axis and has a specific angle with respect to the y-axis as an end surface, and is configured, for example, by being held by a casing such as TEMPAX glass. Furthermore, in FIG. 19, unlike the optical systems of the first and second embodiments, the flat surface 21 side of the lens matrix 2 is directly attached to the end face of the optical fiber 1, and the convex surface 23 of the fiber matrix 1 has a double period. The side faces the opposite side of the flat surface 21. The relative position of the fiber matrix 1 and the lens matrix 2 is set in such a manner that, in the x-axis direction, the optical axis A of the plano-convex lens_C The center lines of the adjacent fibers of the optical fiber matrix 1 (the center lines of the first optical fiber 11A and the second optical fiber 11B in the figure) are the same, and in the y direction, the optical axis A of the lens_C The plane formed by the matrix is consistent with the plane formed by the center line of the fiber matrix 1, and in the z direction, the distance between the end face of the fiber matrix 1 and the convex vertex of the lens matrix 2 and the focal length f of the concave side of the plano-convex lens_c Consistent. On the right side of FIG. 19, the air layer 3 with a certain interval is perpendicular to the optical axis A_C A partial transmission film 41 having a function of reflecting / transmitting light of a specific wavelength at a desired ratio is provided in parallel with the z-axis. In the first and second embodiments, a part of the transmissive film 41 is directly mounted on the flat side of the lens matrix 2, but in this embodiment, it is individually mounted on a glass substrate 42 having the same refractive index as the lens matrix 2. In addition, in this configuration, the path of light emitted from the end face P1 of the first optical fiber 11A is approximately studied with light rays. Since the end face P1 of the first optical fiber 11A is located on the concave focal plane, the light emitted from the end face P1 of the first optical fiber 11A from there and emitted from the corresponding convex surface 23 of the lens matrix 2 is directed toward the optical axis A._C Side refraction while becoming with the optical axis A_C At an angleThe parallel rays of light travel in the air layer 3. Among them, from the fiber end P1 and the optical axis A_C When the light rays emitted in parallel, that is, the central light rays of the emitted light reach the partially transmitted film 41, they pass through the focal point of the convex side corresponding to the first aspherical surface A1. The thickness of the air layer 3 is set exactly to the convex focal length f_v And the part becomes a flat surface, and a part of the transmissive film 41 is applied to the part. Therefore, a part of the specific intensity of the parallel light is transmitted through the part of the transmissive film 41 and relative to the optical axis A_C forThe angle is straight, but the remaining intensity is partially reflected by the partially transmitting film 41 and is relative to the optical axis A._C The symmetrical x-direction position reaches the surface of the lens matrix 2 again. The reflected light that has reached the surface of the lens matrix 2 is parallel light that passes through the focal point of the convex side, and is along the optical path that exits from the first optical fiber 11A and is incident from the surface of the lens matrix 2 with respect to the optical axis A._C Symmetric path, finally focused to a position relative to the optical axis A_C An end face of the second optical fiber 11B at a position symmetrical to the first optical fiber 11A. Here, if the thickness of the air layer 3 is set to the convex side focal length f_v Thin, the thickness of reflected parallel light is f compared to air layer 3_v Optical axis A_C The side surface is here where the parallel light is not bundled and further diffuses on the end face of the second optical fiber 11B. On the other hand, the thickness of the air layer 3 is thicker than f_v In this case, the reflected light further reaches the outer surface of the lens, and the parallel light is excessively collected, and as a result, it diffuses on the end surface of the second optical fiber 11B. In either case, the optical axis of the reflected light is offset from the optical axis of the second optical fiber 11B. Therefore, an important point in this embodiment is that the distance between the end faces of the first and second optical fibers 11A and 11B and the convex apex of the plano-convex lens is set to the concave focal length f._c The distance between the plano-convex lens and the partially transmitting film 41 is the convex side focal length f_v . In addition, as shown in FIG. 19, the light transmitted by the partially transmitting film 41 is shown in FIG. 19. If the refractive index n of the substrate to which the partially transmitting film 41 is attached and the refractive index n of the lens matrix 2 are made,_c The same, although not shown in the figure, it is emitted at an angle ψ. In addition, if the glass substrate 42 to which a part of the transmissive film 41 is attached is a parallel substrate, when it is finally emitted to the air layer 3 at an angleShoot out. In addition, when a low-loss coupling is desired between the optical fibers 11A and 11B with such a reflection optical system, the surface shape required by the convex surface 23 is generally called an aspheric surface. The aspheric shape is different depending on the setting form of the optical system, and the method for obtaining the aspheric shape in this embodiment will be described with reference to FIG. 20. In FIG. 20, for convenience of description, it is described that light is emitted from the second optical fiber 11B, but the optical system is relative to the optical axis A._C Symmetry, so this is not a compromise on rationality. As shown in the figure, the setting includes the optical axis A_C The xz plane, and the lens curved surface as the rotation curved surface with the z axis as the axis of symmetry, and the shape of the xz section as Z (x). The optical system set here is a model in which the third quadrant in the xz plane is placed parallel to the z-axis and placed on the concave side focal distance f from the x-axis._c The light emitted from the second optical fiber 11B at an upward position at an angle of θ is refracted at the intersection with the hypothetical curve Z (x), and reflected at the reflection angle illustrated in FIG. 20Travel in the air layer 3. The above formula (1) holds based on Snell's law of the refracting portion. If the angle formed by the tangent to the curve Z (x) of the light incident position and the x-axis is set to θ_t , According to the angular relationship in FIG. 20, it is easy to know that there is a relationship of the following formula, that is, (Equation 18). From the formulas (1) and (18), the following formula holds. (Equation 19)Here, because the angle θ_t Since the tangent angle of the curve Z (x), the above formula (4) holds. In addition, the outgoing light from the optical fiber 11B and the optical axis A_C The tangent of the formed angle θ satisfies the following formula, that is, (Equation 20). By changing θ of equation (4)_t Θ of equation (20) is substituted into equation (19) to obtain a differential equation related to Z (x). Calculate the curve according to the boundary conditions of formula (4), formula (19) to formula (20), and the origin (0,0) of the following formula, that is, (numerical formula 21)However, it becomes a complex nonlinear differential equation that cannot be solved analytically, and is obtained by approximate calculation. At this time, since it may be solved analytically, the function form is determined based on this in advance. Cases that can be solved analytically are the optical fibers 11A and 11B and the lens optical axis A_C Consistent situation. On the optical fibers 11A and 11B and the lens optical axis A_C In the same situation, the reflection angle of Figure 20f When it becomes zero, Z (x) is obtained analytically and becomes an ellipse of Formula (22). [Equation 22]Here, C_e Is a curvature, and is the following formula, that is, (Equation 23), K_e Is a conic constant, and is the following formula, that is, (Equation 24). As in this embodiment, the optical fiber 11B is from the optical axis A_C In the case of a shift, it is assumed that Equation (22) is used as the basic equation and an approximation term based on the polynomial shown below is added. [Equation 25]Here, n is an integer of 2 or more, and B₃ , B₄ , ... B_{2n - 1} , B_2n Aspheric coefficient. After determining the number of times corresponding to the target accuracy in equation (25), substitute equations (4), (19), and (20) to calculate the residual error, and find the curvature C that is the global solution according to the damping least square method._e Cone constant K_h , And aspheric coefficient B_{2n - 1} , B_2n Combination. If the coefficient value in formula (25) is specified, the surface shape can be processed in the mold. The coefficient to be specified can be determined by equations (4), (19) to (20). Even without such calculations, the possibility can be verified. First, the names and symbols of the parameters shown in FIGS. 19 and 20 are shown in the left column of FIG. 21. These are the same as FIG. 5 related to the first embodiment, but the major difference is that the orientation of the lens matrix 2 with respect to the fiber matrix 1 is reversed, and the reflection angleThe magnitude relationship with the lens center incident angle ψ is also reversed. In FIG. 19 and FIG. 20, the light emitted from the first optical fiber 11A having an end surface directly adjoining the concave focal surface and emitted from the lens surface through a plano-convex lens becomes the optical axis A._C PresentAngle of parallel light. Therefore, for these rays to enter the lens optical axis A_C The light at the intersection with the lens surface, because the tangent plane of the lens surface is exactly perpendicular to the optical axis A_C The parallel z-axis, so the incident angle ψ and the exit angle of the lens center of the lightWith refractive index n_v , N_c In the meantime, Snell's law holds, that is, (Equation 26). Since the fiber matrix 1_f Matrix, and lens matrix 2 is 2d twice_f Matrixization, so if the fiber spacing d is given_f Incident angle ψ and exit angle from lens centerValue, the focal length f on each of the convex and concave sides_v , F_c It is determined by the following formulas (27) and (28). (Equation 27)(Equation 28)In the above formulas (26) to (28), no approximate operation is added and the formula is strict, and the optical axis A that satisfies this relationship is_C The surface of rotation that is the axis of symmetry becomes a higher-order surface based on a rotating ellipse. Determine the two focal lengths f of the convexo-concave of the plano-convex lens according to equations (27) and (28)_v , F_c That is, the distance between the optical fibers 11A and 11B and the plano-convex lens and the thickness of the plano-convex lens are determined. The limiting factors of such an optical system are the same as those of the second embodiment. Trying to substitute these equations (26) to (28) into actual possible values, and also using the above equations (14) and (15) to calculate the values below the lens center incident angle ψ in Figs. 19 and 20 This is the estimation example of FIG. 21. Fiber spacing d_f Choose 250 μm and 127 μm, and the refractive index of the lens is 1.501. The refractive index of the glass with high weather resistance is 1.501. Second, the reflection angleThis embodiment considers the application of an optical tap module using a fiber pair consisting of optical fiber 11A and optical fiber 11B as the main optical path, and a part of the transmissive film 41 being a so-called tap film that reflects more than 90% and transmits a few%. It is set at an angle at which part of the transmitted light does not produce polarization dependence. At fiber spacing d_f For 250 μm and 127 μm, the convex focal length f_v It is 889.4 μm and 451.8 μm. At this time, the diameter BD of the light beams emitted from the optical fiber 11A on the lens surface becomes smaller than the fiber interval d, respectively._f 214.6 μm, 109.0 μm, so this light does not touch the adjacent lens. Also, because the optical axis A of the lens surface_C The approximate radii of curvature of the upper spheres are 445.6 μm and 226.4 μm, so they sufficiently exceed the mechanical processing limit of the mold, that is, 150 μm, and can be used for mold lens processing. In short, it can be seen that the structures shown in Figs. 17, 18, and 19 can also be realized. Here, the limitation of the beam diameter BD of the incident light emitted from the optical fiber on the surface of the lens matrix 2 shown in FIG. 5 and FIG. 21 and the conditions of the radius of curvature used for mold processing will be described. The refractive index of oxide glass that can be molded by a mold reaches n at a value of 1.55 μm_c = 1.426 to 2.068. From Equations (1) to (15) and Equations (26) to (28), it can be confirmed that (for example, Sumita Optical Glass: Glass Catalogue Ver.9.01), the fiber spacing d listed in Figs. 5 and 21_f Refractive index n_v , And reflection angleRefractive index n_c These conditions are always met within the scope. (Seventh embodiment) Fig. 22 shows an optical system according to this embodiment. The plano-convex lens 2 of this embodiment is a bi-modal bi-modal lens of which the first aspherical surface A1 and the second aspherical surface A2 are convex in the fifth and sixth embodiments. In the seventh embodiment and the eighth embodiment, the first aspherical surface A1 is referred to as a first convex surface A1, and the second aspheric surface A2 is referred to as a second convex surface A2. The shape and manufacturing steps of the convex surface 23 of this embodiment are the same as those of the third embodiment and the fourth embodiment. (Eighth Embodiment) Fig. 23 shows a configuration example of an optical fiber matrix module according to this embodiment. The optical fiber matrix module of this embodiment is a plano-convex lens 2 of the seventh embodiment applied to the convex surfaces 23-1 to 23-4 of the optical fiber matrix module of the sixth embodiment. The optical system of FIGS. 22 and 23 will be described with reference to FIG. 24. The following directions are described following the orthogonal xyz coordinate axes in the figure. At the left end of the figure, a period interval d is arranged in the xz plane parallel to the z axis in the x axis direction._f An optical fiber matrix 1 in which optical fibers are arranged. The optical fiber matrix 1 has a plane that is parallel to the x-axis and has a specific angle with respect to the y-axis as an end surface, and is configured, for example, by being held by a casing such as TEMPAX glass. Furthermore, in FIG. 24, unlike the optical systems of the third and fourth embodiments, the flat surface 21 side of the bimodal lens matrix 2 is directly attached to the end face of the optical fiber matrix 1, and the double period of the optical fiber matrix 1 The bimodal convex surface 23 side faces the opposite side of the flat surface 21. The bimodal convex surface 23 has a lens central axis A parallel to the z-axis_C , And the plane perpendicular to the z-axis is the common plane, and the period of the fiber-optic matrix 2 is 2d in the x-axis direction, and the interval is 2d_f And separated from adjacent lenses by an adjacent interval d_n And matrix. The bimodal convex surface 23 is composed of a first convex surface A1 and a second convex surface A2. The first convex surface A1 is a curved surface that is centered on a line R1 that is included in a surface Pc formed by the fiber matrix and is parallel to the z-axis, and functions as a lens. The optical axis of the first optical fiber 11A is shifted inward (on the center axis Ac side) by a specific distance. The second convex surface A2 is formed in a shape symmetrical to the first convex surface A1 with the saddle portion of the width ws with respect to the lens central axis Ac. The interval between the rotation centerlines R1 and R2 of the first and second convex surfaces A1 and A2 is the peak interval d._p Set to d_f A small specific length of distance. The convex side of the bimodal lens matrix 2 is provided with a partially transmitting portion 4 having a partially transmitting film 41 perpendicular to the z-axis with the air layer 3 interposed therebetween. As shown in the figure, the thickness of the air layer 3 is set so that the distance between the bi-convex convex surface 23 and the opposite part of the transmissive film 41 is thicker than the convex side focal length f._v Reflective layer thickness t_r . The relative position of the fiber matrix 1 and the bimodal lens matrix 2 is set in such a manner that, in the x-axis direction, the central axis A of the bimodal lens_C The center lines of the adjacent fibers of the optical fiber matrix 1 (the center lines of the first optical fiber 11A and the second optical fiber 11B in the figure) are the same, and in the y direction, the central axis A of the lens_C The plane formed by the matrix is consistent with the plane formed by the center line of the fiber matrix 1, and in the z direction, the distance between the end face of the fiber matrix 1 and the convex vertex of the bimodal lens matrix 2 and the focal length f of the concave side of the plano-convex lens_c Consistent. On the right side of FIG. 24, the air layer 3 with a certain interval is perpendicular to the center axis A_C A partial transmission film 41 having a function of reflecting / transmitting light of a specific wavelength at a desired ratio is provided in parallel with the z-axis. In the third and fourth embodiments, a part of the transmissive film 41 is directly mounted on the flat side of the lens matrix 2, but in this embodiment, it is individually mounted on a glass substrate 42 having the same refractive index as the lens matrix 2. In addition, in this configuration, the path of light emitted from the end face of the first optical fiber 11A is approximately studied with light rays. Since the end face of the first optical fiber 11A is located on the concave focal plane, and the centerline R1 of the first convex surface A1 in the bimodal convex surface is shifted in the x direction relative to the fiber centerline as described above, The end surface P1 is a point light source, and the light emitted from the end surface P1 and incident on the first convex surface A1 of the lens matrix 2 is directed toward the central axis A._C Side refraction, with the central axis A_C At a specific angleThe parallel rays of light travel in the air layer 3. Among them, the ends of the optical fibers 11A and 11B and the central axis A_C That is, the light rays emitted in parallel with the z-axis, that is, the central rays of the emitted light, pass through the convex focal point after being emitted from the bimodal lens. As described above, since the thickness t_r Thicker than the focal length f_v And part of the transmissive film 41 is located at the above-mentioned central light and the lens central axis A_c The point of intersection, therefore, a part of the specific intensity of the parallel light is partially transmitted through the film 41 and is relative to the central axis A_C Straight forward at an angle of ψ, but the rest of the intensity is reflected by the partially transmitting film 41, relative to the central axis A_C The symmetrical x-direction position reaches the second convex surface A2. The reflected light that has reached the second convex surface A2 is parallel light that passes through the focal point of the convex side, and is along the optical path that exits from the first optical fiber 11A and enters the first convex surface A1 with respect to the central axis A._C Symmetric path, finally focused to A relative to the central axis A_C An end face P2 of the second optical fiber 11B at a position symmetrical to the first optical fiber 11A. Here, if the thickness of the air layer 3 is set to be thicker than the thickness t of the reflective layer_r Thin, the parallel light is reflected on the second convex surface A2, compared to the thickness of the air layer 3 is t_r Optical axis A_C On the side surface, the parallel light beam is insufficiently condensed there and further diffuses on the end surface of the second optical fiber 11B. On the other hand, the thickness of the air layer 3 is thicker than t_r In this case, the reflected light further reaches the outer surface of the lens, and the parallel light is excessively collected, and as a result, it diffuses on the end surface of the second optical fiber 11B. In any case, the optical axis of the reflected light is offset from the optical axis of the second optical fiber 11B. Therefore, the important point in this embodiment is that the distance between the end faces of the first and second optical fibers 11A and 11B and the convex apex of the bimodal lens is set to the concave focal length f._c And the distance between the bimodal lens and the partially transmitting film 41 is a specific reflection layer thickness t_r . In addition, as shown in FIG. 24, the light transmitted by the partially transmitting film 41 is shown in FIG. 24. If the refractive index of the substrate to which the partially transmitting film 41 is attached and the refractive index n of the lens matrix 2_c The same, although not shown in the figure, it is emitted at an angle ψ. In addition, if the glass substrate 42 to which a part of the transmissive film 41 is attached is a parallel substrate, when it is finally emitted to the air layer 3 at an angleShoot out. Next, the above description is formulated using a formula. In FIG. 24, the light rays emitted from the first optical fiber 11A having the end surface on the concave focal surface and entering the first convex surface A1 of the bimodal lens convex surface 23 through the lens matrix 2 become the lens central axis A._C PresentAngle of parallel light. Among these rays, the rays incident on the peak of the first convex surface A1 (the intersection point of the central symmetry line R1 and the first convex surface), because the tangent plane of the lens surface of the incident point is perpendicular to the central axis A_C , So the incident angle ψ and the exit angle at the center of the peak of the lightAnd refractive index n_v , N_c In between, Snell's law holds, that is, (Equation 42). Since the fiber matrix 1_f Matrix, and lens matrix 2 is 2d twice_f Matrix, so the focal length f on each side of the concave and convex sides_c , F_v Based on fiber spacing d_f Peak interval d between the first convex surface A1 and the second convex surface A2_p , Lens center incident angle ψ, and exit angleThe value is determined by the following equations (43) and (44). (Equation 43)(Equation 44)The thickness t of the reflective layer_r Similarly, the following formula holds: (Equation 45). The first and second convex surfaces A1 and A2 constituting the double peaks may all satisfy the above formulas (42) to (45), but satisfy these relationships and be parallel to the lens central axis A._C The curved surface whose axis is the axis of symmetry becomes a higher-order curved surface based on a rotating ellipse, and is generally called an aspheric surface. If fiber spacing d is given_f Lens peak interval d_p Lens refractive index n_c Refractive index n_v , And reflection angle, The two focal lengths f of the asperity of the bimodal lens are determined according to equations (43) and (44)._c , F_v To determine the thickness f of the lens_c And the thickness t of the air layer 3 is determined according to formula (45)_r . Next, the conditions for establishing such an optical system will be described. In order to achieve the low-loss coupling between the first optical fiber 11A and the second optical fiber 11B, it is necessary to suppress the shading of the lens surface as much as possible. The outgoing light from the first optical fiber 11A is diffused according to the NA of the optical fiber, but the diffusion often manifests as the transmission of a Gaussian beam with the fiber end as the waist position of the beam. The power of the Gaussian beam exiting from the fiber end and reaching the lens surface is distributed from the center of the beam to 1.73 times the beam radius ω to become 99.75% of the total power. Therefore, if the range so far is set to the beam diameter BD of the light beam reaching the lens surface 23, it is given by the following formula, that is,. Here, ω₀ And λ are the mode radius of the optical fiber 11A and the wavelength of light, respectively. Secondly, the conditions required for the beam diameter BD of the lens surface of type II are the same as those for the type I described above, and the conditions are the same as those of formulas (38) and (39). However, the peak curvature radius R_p The required condition is replaced by the following formula, that is, (Equation 47). Based on the above, regarding the configuration of type II, the peak interval d is the same as that of type I._p With beam diameter BD, peak curvature radius R_p (According to equation (47)) and the graph of the relationship between the two condition indexes are shown in Figs. 25 and 26. The value used in the calculation is the same as the type I described in the third and fourth embodiments. Figure 25 shows the fiber spacing d in the type II configuration._f In the case of 250 μm, for each peak interval d_p Refractive index n_c With peak curvature radius R_p The relationship is obtained by plotting the graph. According to equations (42) to (44) and equations (46) to (47), for each peak interval, as the refractive index of the lens increases, the refractive power of the light increases, so the peak curvature radius increases. Regarding the peak interval, as the light increases toward the center of the peak, the radius of curvature is reduced in order to maintain the same refractive power. In this graph, the three-dotted line in the graph is applied to the two-peak condition, the two-piece condition, and the mold processing condition. The two-piece condition is specified by formula (38), the bimodal condition is specified by formula (39), and the mold processing conditions are specified by formula (47). Below the value obtained based on the bimodal condition is the n of the optical system that can form a bimodal morphology without shading_c -R_p region. Below the value obtained based on the two-piece condition, n is an optical system that can form a two-piece optical system without shading._c -R_p region. Higher than the value obtained according to the processing conditions of the mold, it becomes a formable n._c -R_p region. It can be seen that the area obtained according to the two-peak condition and the mold processing conditions is wider than the area obtained according to the two-chip conditions and the mold processing conditions, and the design freedom is relaxed to about 2 times. In particular, under bimodal conditions, an optical system with a larger radius of curvature can be constructed, which means that the difficulty of mold processing is lower. Figure 26 shows the fiber spacing d in the type II configuration._f For the case of 127 μm narrower than that in FIG. 25, the interval d for each peak is_p Refractive index n_c With peak curvature radius R_p The relationship is obtained by plotting the graph. From equations (42) to (44) and equations (46) to (47), as in FIG. 25, for each peak interval, as the refractive index of the lens increases, the refractive power of the light increases, so the peak radius of curvature Increase. Regarding the peak interval, as the light increases toward the center of the peak, the radius of curvature is reduced in order to maintain the same refractive power. In this graph, as in FIG. 25, the conditions of Expressions (38) to (39) and (47) are applied as three dotted lines in the graph. It can be seen at a glance that the area where the bimodal morphology can be achieved is definitely wider than the two-chip morphology. If distance from fiber d_f = 250 μm, as the fiber spacing d_f Narrow and achievable n_c -R_p The area is also narrowed, and the area where the bimodal shape can be realized becomes a triangular area surrounded by a dotted line of the bimodal condition and the mold processing condition, and cannot be constituted when the lens refractive index nc is 1.44 or less. However, when the refractive index of BK7, which is a representative glass material of borosilicate glass with higher reliability, is 1.501, although the peak interval d_p It has a narrow width of 103.5 to 106.1 μm, but it can constitute an optical system, and it can be seen that the bimodal shape can cope with miniaturization. On the other hand, under two-chip conditions,_c A limited area of 1.64 or more and a peak interval of 111 to 116 μm is also achieved. This high-refractive-index region also includes regions that cause problems such as the occurrence of yellowing in terms of reliability. It has to be said that the practical applicability is quite low, and it can be considered as d_f At 127 μm, only two-piece morphology can be used to a very limited extent. In the above, if two pieces are compared with the bimodal structure, the following can be described. In consideration of 2 main parameters, the lens refractive index n_c With peak curvature radius R_p In this case, the bimodal composition system n_c -R_p The area is about two to three times that of the two-piece structure, and the design freedom is high. Double-peak configuration can also cope with narrower fiber spacing d_f And suitable for miniaturization. Bimodal composition due to peak curvature radius R_p A larger value can be selected to increase the lens diameter, so the coupling efficiency between fibers can also be maintained higher. The bimodal structure is easier to make because the radius of curvature of the hole when making the mold is larger. For the differences between Types I and II, at the fiber spacing d_f In the case of 250 μm, the two conditions are approximately equal to each other._p The area is 14.2 to 14.3 μm. On the other hand, in terms of bimodal conditions, it can be seen that the peak interval d of the type I system is_p It allows the width to be expanded by about 1.5 times, making it easy to make lenses. Especially at fiber spacing d_f In the case of 127 μm, type d_p The allowable width is 3.9 μm. In contrast, the allowable width of Type II is only 2.6 μm. The difference of 1 μm or more of the allowable width is very large in terms of mold making, and Type I is relatively easy to make. (Ninth Embodiment) Fig. 27 shows an example of an optical fiber matrix module according to this embodiment. The fiber matrix module shown in FIG. 27 includes the fiber matrix module shown in FIG. 2, a light shielding plate 7, and a lens matrix 9. The light shielding plate 7 functions as an optical component, and the lens matrix 9 functions as a second lens matrix. The fiber matrix module of this embodiment may also be a fiber matrix module of the fourth embodiment shown in FIG. 10. The light shielding plate 7 has a plurality of through holes 71. Each parallel light transmitted through the reflecting surface of the partially transmitting film 41 is incident on one end of a different through hole 71. Then, the parallel light that has passed through the through-holes 71 is emitted from the other end of each through-hole 71. The lens matrix 9 condenses each light emitted from the other end of the plurality of through holes 71 to a point defined for each of the through holes 71. Just set the optical function element at this point. An example of the light receiving module of this embodiment is shown in FIG. 28. The light receiving module shown in FIG. 28 includes the optical fiber matrix module shown in FIG. 27 and a light receiving element matrix 8. Each light-receiving element 81 provided in the light-receiving element matrix 8 receives each light condensed by the lens matrix 9. The light receiving module shown in FIG. 28 can be used as a 4-matrix light tap monitoring module. The application area of this embodiment is, for example, an optical communication system with a wavelength of 1.55 μm. The module includes a fiber matrix 1, a lens matrix 2, a partially reflecting portion 4 having a partially transmitting film 41, a light shielding plate 7, a lens matrix 9, and a light receiving element matrix 8 from the left side of the figure. For fiber spacing d_f Each of the parameters, as an example, can be realized in reality if the values shown in FIG. 5 are used. First, the operation and function of the module will be described. 95% of the light incident from the optical fiber 11A to the lens matrix 2 is partially transmitted through the film 41 at a reflection angle(5 degrees) is reflected and incident on the second optical fiber 11B, and 5% of the incident light intensity is tapped and returned to the main line. The 5% -intensity tapped light system becomes the air layer at the rear and emits at an exit angle ψ (7.5 degrees). However, in the rear section of the partially transmitted film 41, in order to prevent the reduction of crosstalk caused by the mixing of tap lights in space transmission, A light shielding plate 7 provided with a through hole 71 is provided. The light shielding plate 7 has a size matching the external shape of the lens matrix 2, and a through hole 71 having a beam diameter is provided at a central portion of the light shielding plate 7 in cooperation with the tap optical path. A lens matrix 9, which is the same as the lens matrix 2, is provided in the rear stage of the light shielding plate 7 opposite to the lens matrix 2. The lens matrix 9 condenses the tap beam transmitted and diffused in space to the light receiving surface of the light receiving element 81. Each of these constituent elements will be described below. Fiber Matrix 1: Fiber Matrix 1 uses 250 μm spaced 8 matrix wavelength 1.3 / 1.55 μm single-mode ribbon fibers as fiber components. They were arranged on a TEMPAX glass, 60-degree V-groove plate with a thickness of 1 mm, covered with a 1 mm-thick top cover, fixed with a UV (Ultraviolet) adhesive, and polished at the end surface to produce a fiber matrix 1 for connection. The matrix spacing is the same as the ribbon fiber used is 250 μm. The optical axis of the optical fiber is the z-direction in FIG. 28, and the end faces connected to other components are parallel to the x-axis, and in order to reduce the return light caused by the end-face reflection, it is set to be inclined 8 degrees from the y-axis direction. Moreover, the angle of the core end surface with respect to the optical axis of the fiber is not limited to 8 degrees. An AR (Anti-Reflection) coating with a wavelength of 1.55 μm is applied to the end surface inclined at 8 degrees. Full width is 4 mm. Lens matrix 2: It is composed of borosilicate glass with a refractive index of 1.501 at a wavelength of 1.55 μm, and is on the upper surface of a flat glass with a thickness of 13,690 m (z direction), at the center of 4000 × 2000 μm (x × y) A convex surface 23 having a first aspherical surface A1 and a second aspherical surface A2 is formed at a matrix interval of 500 μm. A flat portion having a thickness of 1 μm is provided between the adjacent convex surfaces 23, and the amount of depression, that is, the amount of depression from the flat portion (lens holding surface) is, for example, 69 μm. Spacers 22 are integrally formed at both ends in the x direction of the lens matrix 2 during the lens molding process. The spacer 22 is a trapezoidal convex portion, the surface of which is an angle that matches the inclined end face of the optical fiber matrix 1 by 8 degrees, and its area is, for example, 1 × 1.5 mm (x × y) on one side. The height of the spacer 22 is preferably such that, for example, the lens optical axis position (Ac) becomes a specific convex-side focal length f._v (Here is 947.3 μm). Here, the angle of the spacer 22 will be described with reference to FIG. 33. Normal line L at the core end face of the optical fiber 11_n The angle with respect to the optical axis of the optical fiber 11, that is, the z-axis is set to θ₁ , The center light of the light emitted from the core end face of the optical fiber 11 to the air layer 3 is relative to the core end face normal L_n The angle is set to θ₂ In the case, according to Snell's law, the angle θ₁ With angle θ₂ The following relationships are satisfied. (Equation 51)Here, n_f Refractive index of transmitted light of the optical fiber 11. Therefore, in n_f Is 1.445, the refractive index n of the air layer 3_c Is 1 and the angle θ₁ When set to 8 degrees, the angle θ₂ It was 11.6 degrees. The case where the optical coupling between the optical fiber and the lens system becomes the highest efficiency is the case where the outgoing light from the optical fiber 11 is perpendicular to the lens surface. In this case, as is clear from FIG. 33, the angle between the lens-side flat surface 22B of the spacer 22 and the inclined end surface 22A of the fiber matrix side, that is, the inclination angle of the spacer 22 also θ₂ Equal to 11.6 degrees. From another perspective, the angle θ of the spacer 22₂ Becomes the angle θ other than the end face of the optical fiber 11₁ In addition to (8 degrees), an angle obtained from the refraction angle (3.6 degrees) of the optical fiber optical axis (z-axis) in the air layer 3 is added. An incident angle is attached to the flat surface 21 of the lens matrix 2The transmission film 41 is set to 5 degrees. The reflection / transmission ratio is preferably 95% / 5%. As the material, for example, SiO formed by ion beam assisted evaporation can be exemplified.₂ -TiO₂ Multilayer film. Light-shielding plate 7: The light-shielding plate 7 is composed of a rectangular infrared-absorbing glass having a shape of 4000 × 2000 × 1000 μm. In the central part, as shown in FIG. 27 and FIG. 28, a 30 μm square through hole 71 is formed in parallel with the xz plane in parallel with the xz plane to form an angle of incidence ψ of the lens center, i.e., 7.5 degrees with the z-axis direction. . The x-direction matrix pitch is 500 μm, which is the same as the lens matrix 2. When the beam diameter of the tap light is 227.4 μm as shown in FIG. 5, it is transmitted without being in contact with the wall of the through hole 71 of the light shielding plate 7, but is generated by the reflection and transmission of the lens matrix 2 or a part of the transmission film 41 in the previous stage. The diffuse reflection component caused by the irregular structure is prevented by the light shielding plate 7 and prevents the light receiving element matrix 8 from reaching the crosstalk. Lens matrix 9: Here, the lens matrix 9 is the same as the lens matrix 2. Generally, the light receiving surface of the light receiving element 81 is about 1 mm away from the package surface. Therefore, a focal length adjustment resin 91 is inserted between the lens matrix 9 and the light receiving element matrix 8 to make it longer focal length than the lens matrix 2 and the light receiving element matrix 8 The light-receiving surface of the middle light-receiving element 81 condenses light. The orientation of the lens matrix 9 is opposite to that of the lens matrix 2 in order to fill the space between the lens matrix 9 and the light receiving element matrix 8 with the focus adjustment resin 91. The lens matrix 9 is preferably applied with an AR coating only on the flat surface 21 side. Light receiving element matrix 8: The light receiving element 81 is, for example, an InGaAs photodiode matrix having a light receiving diameter of 80 μm and a 500 μm pitch 4 matrix. The diode matrix is sealed, and the distance from the package surface to the light receiving portion of the light receiving element 81 is 1 mm. As can be seen from the side view shown in FIG. 28, the light receiving element matrix 8 is connected to the lens matrix 9 obliquely from the z-axis direction, that is, the optical axis. As shown in the side views of FIG. 27 and FIG. 28, since the connection interface from the fiber matrix 1 to the light receiving element matrix 8 remains inclined, it has a structure that prevents reflected return light. Assembly steps: The steps have 3 steps. The first step is the connection of the fiber matrix 1 and the lens matrix 2. This is connected by the same steps as the usual fiber waveguide connection: In the fiber waveguide connection device, the aligning light is incident from the two ends of the fiber matrix 1, namely, the optical fiber 11A-1 and the optical fiber 11A-4, while monitoring from the optical fiber 11B-1 2. The light side of the optical fiber 11B-4 is fixed by 2-axis alignment. The connection portion is between the spacer 22 and the optical fiber matrix 1. The second step is the connection of the light shielding plate 7, the lens matrix 9, and the light receiving element matrix 8. These connections are sequentially arranged under the microscope with a light-receiving element matrix 8, a lens matrix 9, and a light-shielding plate 7, so that the light-receiving surface of the light-receiving element 81 can be seen through the through-hole of the light-shielding plate 7, and the core is aligned by visual alignment. And fixed with adhesive. The third step is to make the alignment light incident on the optical fibers 11A-1 and 11A-4, while monitoring the output of the light receiving element matrix 8 while attaching the lens matrix 2 with the optical fiber matrix 1 and the light receiving element matrix 8 and the lens matrix 9 The light shielding plate 7 is connected and fixed. Characteristics: The characteristics of the manufactured 4 ch tap monitoring module at a wavelength of 1.55 μm are an insertion loss of 0.4 to 0.5 dB, a reflection attenuation of 46 dB or more, and a light receiving sensitivity of 50 to 60 mA / W. Adjacent crosstalk is also above 45 dB. FIG. 34 shows another form of the optical fiber matrix module of this embodiment. The fiber matrix module shown in FIG. 34 has an AR plate 101 attached to the end face of the fiber matrix 1, and includes a GRIN (Graded Index) lens matrix 109 instead of the light shielding plate 7 and the lens matrix shown in FIG. 27. 9. The fiber matrix module may also be the fiber matrix module of the fourth embodiment shown in FIG. 10. The AR plate 101 is formed by attaching an AR film to one side of a transparent thin plate having a refractive index approximately equal to the equivalent refractive index of an optical fiber. When it is difficult to directly form an AR film on the end face of the optical fiber matrix 1, use the transparent adhesive patch with the refractive index substantially equal to the AR film 101 on the end face of the optical fiber matrix 1 without the AR film 101 Use it side-by-side for the same effect as a direct AR coating. FIG. 35 shows another aspect of the light receiving module according to this embodiment. The light receiving module shown in FIG. 35 includes the fiber matrix module shown in FIG. 34 and a light receiving element matrix 8. Each light-receiving element 81 provided in the light-receiving element matrix 8 receives each light condensed by the GRIN lens matrix 109. The GRIN lens matrix 109 includes a plurality of GI (Graded Index) optical fibers 174 functioning as GRIN lenses. The GRIN lens matrix 109 has a size matching that of the lens matrix 2 and a GI optical fiber 174 is arranged at the central portion to match the tap optical path. The GI optical fiber 174 is preferably fixed by being clamped by two V-groove plates. Each parallel light transmitted through the partial transmission film 41 is incident on one end of a different GI optical fiber 174. Then, each light emitted from the other end of the GI optical fiber 174 is focused to the points P9-1 to P9-4 specified for each GI optical fiber 174. A light-receiving surface of the light-receiving element 81 is arranged at this point. (Tenth embodiment) Fig. 29 shows an example of an optical fiber matrix module according to this embodiment. The optical fiber matrix module shown in FIG. 29 includes the optical fiber matrix module shown in FIG. 18, a light shielding plate 7, and a lens matrix 9. The light shielding plate 7 functions as an optical component, and the lens matrix 9 functions as a second lens matrix. The fiber matrix module of this embodiment may also be the fiber matrix module of the eighth embodiment shown in FIG. 23. The light shielding plate 7 has a plurality of through holes 71. Each parallel light transmitted through the reflecting surface of the partially transmitting film 41 is incident on one end of a different through hole 71. Then, the parallel light that has passed through the through-holes 71 is emitted from the other end of each through-hole 71. The lens matrix 9 condenses each light emitted from the other end of the plurality of through holes 71 to a point defined for each of the through holes 71. A light-receiving surface of the light-receiving element 81 is arranged at this point. An example of a light receiving module according to this embodiment is shown in FIG. 30. The light receiving module shown in FIG. 30 includes the fiber matrix module shown in FIG. 29 and a light receiving element matrix 8. Each light-receiving element 81 provided in the light-receiving element matrix 8 receives each light condensed by the lens matrix 9. The light receiving module shown in FIG. 30 can be used as a 4-matrix light tap monitoring module. The application area is an optical communication system with a wavelength of 1.55 μm. The module includes an optical fiber matrix 1, a lens matrix 2, a partial transmission film 41 and a glass substrate 42, a light shielding plate 7, a lens 9, and a light receiving element matrix 8 from the left side of the figure. For fiber spacing d_f Each of the parameters, as an example, can be realized in reality if the values shown in FIG. 21 are adopted. First, the operation and function of the module will be described. 95% of the light that is incident from the optical fiber 11A to the lens matrix 2 from the flat surface 21 side without passing through the air layer and exits from the lens surface 23 is partially transmitted through the film 41 at a reflection anglef (8 degrees) After reflection, it returns to the lens matrix 2 again and is incident on the optical fiber 11B. 5% of the incident light intensity is tapped and returned to the main line. The rear section of the 5% intensity tap light system passes through the glass substrate 42 parallel to the partially transmitting film 41 to become an air layer, and the exit angle is(8.0 degrees), but at the rear stage of the glass substrate 42, in order to prevent crosstalk caused by the mixing of tap light transmitted in space, the light shielding plate 7 provided with a through hole 71 is provided. The light shielding plate 7 has a size matching the external shape of the lens matrix 2, and a through hole 71 having a beam diameter is provided at a central portion of the light shielding plate 7 in cooperation with the tap optical path. A lens matrix 9, which is the same as the lens matrix 2, is provided in the same direction as the lens matrix 2 at the rear stage of the light shielding plate 7. The lens matrix 9 condenses the tap beam transmitted and diffused in space to the light receiving surface of the light receiving element 81. The following description will be made with respect to each of the above-mentioned components without overlapping with the ninth embodiment. Optical fiber matrix 1: Unlike the ninth embodiment, an AR coating is not applied to an end surface inclined by 8 degrees. In addition, as in the ninth embodiment, the angle of the core end surface with respect to the optical axis of the optical fiber is not limited to 8 degrees. Lens matrix 2: It is composed of borosilicate glass with a refractive index of 1.501 at a wavelength of 1.55 μm, and is formed at a matrix interval of 500 μm in the positive direction of the z-axis at the center of the lens holding surface parallel to the xy plane The convex surface 23 of the first aspherical surface A1 and the second aspherical surface A2. A flat portion having a thickness of 1 μm is provided between the adjacent convex surfaces 23, and a convex amount, ie, a depression amount, from the flat portion (lens holding surface) is, for example, 75 μm. Spacers 22 are integrally formed at both ends in the x direction of the lens matrix 2 during the lens molding process. The spacer 22 is a trapezoidal convex portion, the surface of the trapezoidal convex portion is parallel to the lens holding surface, and the area thereof is 1 × 1.5 mm (x × y) on one side. The height of the spacer 22 is such that the lens optical axis position (Ac) becomes a specific convex side focal length f_v (Here is 889.4 μm). The flat surface 21 of the lens matrix 2 is parallel to the end face of the optical fiber matrix 1 and is inclined with respect to the y-axis, and the distance between the inclined flat surface 21 and the lens optical axis (Ac) of the lens convex surface 23 becomes the concave focal length f_c = 1342 μm. Partially transmissive film 41 and glass substrate 42: In this configuration, partly transmissive film 41 is attached to transparent glass substrate 42 separated from lens matrix 2 but has the same refractive index n_c By. An incident angle is attached to a glass substrate 42 whose two surfaces are parallel.The partial transmission film 41 is set to 8 degrees. The reflection / transmission ratio is preferably 95% / 5%. As a material, for example, SiO formed by an ion beam assisted evaporation method can be exemplified.₂ -TiO₂ Multilayer film. Light-shielding plate 7: The light-shielding plate 7 is composed of a rectangular infrared-absorbing glass having a shape of 4000 × 2000 × 1000 μm. At the central part, as shown in FIGS. 29 and 30, in accordance with the optical path of the tap light, a lens center incident angle with the z-axis direction is provided in parallel with the xz plane.f That is, a 300 μm square through hole with an angle of 8 degrees. The x-direction matrix pitch is 500 μm, which is the same as the lens matrix 2. When the beam diameter of the tap light is 214.6 μm as shown in FIG. 21, the light is transmitted without being in contact with the wall of the through hole 71 of the light shielding plate 7, but is generated by the reflection and transmission of the lens matrix 2 or the partial transmission film 41 in the previous stage. The diffuse reflection component caused by the irregular structure is prevented by the light shielding plate 7 and prevents the light receiving element matrix 8 from reaching the crosstalk. As shown in the side views of FIGS. 29 and 30, the connection interface from the fiber matrix 1 to the light-receiving element matrix 8 all remains inclined, so it has a structure that prevents reflected return light. Assembly step: The difference from the ninth embodiment is that in the first step, the lens matrix 2 and a part of the transmissive film 41 are connected first. In this step, since a part of the transmissive film 41 is an ordinary flat plate, the alignment operation is not required, and the connection can be performed only by the mold alignment operation. The rest is the same as the ninth embodiment. Characteristics: The characteristics of the manufactured 4 ch tap monitoring module at a wavelength of 1.55 μm are an insertion loss of 0.4 to 0.5 dB, a reflection attenuation of 46 dB or more, and a light receiving sensitivity of 50 to 60 mA / W. Adjacent crosstalk is also above 45 dB. This is the same as the third embodiment. (Eleventh embodiment) In the above embodiment, the matrix is a one-dimensional array, but it may be a two-dimensional matrix. In this case, the fiber matrix modules shown in FIG. 2 or FIG. 18 are arranged side by side in the y direction. At this time, the fiber matrix is the most problematic, but the fiber matrix 1 can be realized according to Patent Document 2. FIG. 31 shows a connection surface of the optical fiber matrix 1 as viewed from the z direction. The optical fiber matrix 1 shown in FIG. 31 includes V-groove plates 13-2 to 13-5 to which a 60-degree V-groove 14 for the optical fiber matrix is applied. On the V-groove plates 13-2 to 13-5, on both sides of the matrix of the V-groove 14, V-grooves 15-1 and 15-2 for vertical alignment are provided. Furthermore, alignment grooves 15-3 and 15-4 are formed on the back surface of the V-groove plates 13-2 to 13-5 at the same x-direction positions as the front side. The alignment optical fiber 12 may be the same as the optical fibers 11A and 11B shown in the figure. In this case, if the opening width of the V-groove 14 is set to W₁₄ And the opening width of the alignment trench 15 is set to W₁₅ , Then these settings can be set as follows, that is, (Equation 29)(Equation 30). In this case, when the alignment optical fiber 12 fits into the alignment groove 15, the waveguide optical fiber 11 is pressed by the upper plate and the upper plate. Here, R is the radius of the optical fiber, and d is the distance between the V-groove plate 13-2 to 13-5 and the upper plate. In this embodiment, since d is set to 20 μm, it is set to W₁₄ = 193 μm, w₁₅ = 61 μm. The alignment grooves 15-1, 15-2, 15-3, and 15-4 must be in the same position on the front and back of the V-groove plate in the x direction. The front and back alignments must be in advance in the grooves such as a slicer or cutter. In the groove processing device, it is sufficient to adjust the groove formation position to observe the verticality of the upper and lower focusing axes of the lens barrel with respect to the processing surface. As a result, the 8 × 4 fiber matrix made of TEMPAX glass has a pitch of 250 μm in the x direction and a pitch of 1 mm in the y direction. With this, a 4 × 4 matrix fiber matrix module and a light receiving module with a 500 μm pitch in the x direction and a 1 mm pitch in the y direction can be manufactured. Here, as shown in the side view of FIG. 32, the optical fiber matrix 1 is preferably subjected to an inclination process only to a portion near the optical fiber core. The reason is that if the entire surface of the end surface of the matrix is set to be inclined, it is particularly difficult to realize a two-dimensional matrix of all parts below the lens matrix 2. Processing can use a double-headed cutting machine. This series is equipped with two cutting machines, and it is a device that can continuously process two different types of blades in one step. 2D (two dimensional) matrix of lens matrix 2, 9 or light-shielding plate 7 other than fiber matrix 1 and light receiving element matrix 8 are also used, and they are 4 times of 500 μm pitch in x direction and 1 mm pitch in y direction. × 4 matrix. A side view of the manufactured 4 × 4 tap monitoring module is shown in FIG. 32. In appearance, the top view is exactly the same as that in FIG. 28, and in the side view, it is in the form of being stacked in the y direction. Moreover, this embodiment is not limited to the fiber matrix module shown in FIG. 2 or FIG. 18, and can also be applied to the fiber matrix modules of all the above embodiments. In addition, in all the embodiments described above, the optical design of the first aspherical surface A1 and the second aspherical surface A2 was performed in comparison, but the present invention is not limited to this. For example, the shapes of the first aspherical surface A1 and the second aspherical surface A2 may be different, and the peak positions of the first and second convex surfaces may also be different. In the description so far, it is assumed that the optical axis of the lens Ac is parallel to the plane Pc formed by the optical axis of the optical fiber for convenience. However, in the case where the end face of the optical fiber is tilted as shown in the explanatory diagram of the present invention in order to prevent reflection, it is desirable to perform skew adjustment between the optical fiber matrix 1 and the lens matrix 2 about an axis parallel to the x-axis. (Effects of the Invention) As described above, if the structure of directly connecting the front and rear elements on the flat surface side of the plano-convex lens is provided, a compact optical module can be constructed. In addition, by making the lens surface aspherical as described in the present invention, the lens aperture can be fully used, and even if it is an integrated small-aperture lens, high-efficiency optical coupling can be achieved. Furthermore, since it has a plano-convex structure, it does not require operations such as front-side and back-side facing like a two-convex lens, and also has the advantage that it can be mass-produced by easily matrixing it with a single-sided molding step. According to these contents, it is clear that it contributes greatly to the economicalization of optical communication devices. [Industrial availability] The present invention can be applied to the information and communication industry.

1‧‧‧ Fiber Matrix

2‧‧‧ lens matrix

3‧‧‧air layer

4‧‧‧partial reflection

7‧‧‧shield

8‧‧‧ light receiving element matrix

9‧‧‧ lens matrix

11‧‧‧ Optical Fiber

11A‧‧‧Optical fiber

11A-1‧‧‧Optical fiber

11A-2‧‧‧Optical fiber

11A-3‧‧‧Optical fiber

11A-4‧‧‧Optical fiber

11A-11‧‧‧ Fiber

11A-12‧‧‧Optical fiber

11A-13‧‧‧ Fiber

11A-14‧‧‧ Fiber

11A-21‧‧‧ Fiber

11A-31‧‧‧Optical fiber

11A-41‧‧‧Optical fiber

11B‧‧‧ Fiber

11B-1‧‧‧optical fiber

11B-2‧‧‧Optical fiber

11B-3‧‧‧ Fiber

11B-4‧‧‧ Fiber

11B-11‧‧‧ Fiber

11B-12‧‧‧Optical fiber

11B-13‧‧‧Optical fiber

11B-14‧‧‧ Fiber

11B-21‧‧‧optical fiber

11B-31‧‧‧Optical fiber

11B-41‧‧‧Optical fiber

12-1‧‧‧ Optic Fiber

12-2‧‧‧Alignment fiber

13-1, 13-2, 13-3, 13-4, 13-5‧‧‧V groove plate

14‧‧‧V groove

15-1, 15-2, 15-3, 15-4

21‧‧‧ flat surface

22‧‧‧ spacer

22A‧‧‧inclined face

22B‧‧‧ lens side flat surface

23‧‧‧ convex

23-1 ～ 23-4‧‧‧ convex

41‧‧‧ partially transmissive membrane

42‧‧‧ glass substrate

71‧‧‧through hole

81‧‧‧ light receiving element

91‧‧‧focus adjustment resin

101‧‧‧AR coated board

109‧‧‧GRIN lens matrix

174‧‧‧GI fiber

A1‧‧‧1st aspherical surface

A2‧‧‧2nd aspherical surface

A3‧‧‧ Saddle

A _C ‧‧‧ lens optical axis (lens central axis)

Bc‧‧‧Peak Line

BD‧‧‧Beam Diameter

D _C ‧‧‧The distance between the center line of the optical fiber and the two ends of the lens outer edge in the x-axis direction

D _E ‧‧‧ The distance between the center line of the fiber and the two ends of the lens' outer edge in the x-axis direction

d‧‧‧V distance between groove plate and upper plate

d _f ‧‧‧ fiber spacing

2d _f ‧‧‧ interval

d _n ‧‧‧adjacent interval

d _p ‧‧‧ peak interval

f _c ‧‧‧ concave side focal length

f _v ‧‧‧ convex side focal length

L _n ‧‧‧ normal

n _c ‧‧‧ lens refractive index

n _v ‧‧‧ air refractive index

P1‧‧‧1st position

P2‧‧‧ 2nd position

P3‧‧‧A point on the reflective surface

P4‧‧‧ intersection

P6‧‧‧peak

P7‧‧‧Intersection

P8‧‧‧Peak

P9-1 ～ P9-4‧‧‧‧points

P _C ‧‧‧ specific plane

Pd‧‧‧ projection

R1‧‧‧Straight

R2‧‧‧Straight

t ₁ ‧‧‧ lens thickness

t _r ‧‧‧thickness of reflective layer

W ₁₄ ‧‧‧V Groove opening width

W ₁₅ ‧‧‧ Opening width of registration groove

w _s ‧‧‧ width

x‧‧‧ direction

y‧‧‧direction

z‧‧‧ direction

Z (x) ‧‧‧curve

‧‧‧Fiber reflection angle

ψ‧‧‧Fiber Incident Angle

θ‧‧‧ angle

θ ₁ ‧‧‧ Angle of fiber with respect to normal

θ ₂ ‧‧‧ the angle of the center light of the light emitted from the center end face of the optical fiber to the air layer with respect to the normal

θ _c ‧‧‧ exit angle from lens surface

θ _t ‧‧‧tangent angle

θ _v ‧‧‧ incident angle to lens surface

FIG. 1 shows an example of a plano-convex lens according to the first embodiment. FIG. 2 shows a configuration example of the optical fiber matrix module according to the second embodiment. FIG. 3 is an explanatory diagram of the optical system according to the first and second embodiments. FIG. 4 is an explanatory view of aspherical shapes of the first and second embodiments. Fig. 5 shows an example of parameters in the first and second embodiments. Fig. 6 is a perspective view of a plano-convex lens according to a third embodiment. Fig. 7 shows a first example of a mold for a plano-convex lens according to a third embodiment. Fig. 8 shows a second example of a mold for a plano-convex lens according to a third embodiment. FIG. 9 shows an example of a plano-convex lens according to the third embodiment. FIG. 10 shows a configuration example of an optical fiber matrix module according to the fourth embodiment. FIG. 11 is an explanatory diagram of optical systems according to the third and fourth embodiments. 12 (a) and 12 (b) are first explanatory diagrams of the beam diameter BD on the lens surface in the third and fourth embodiments. 13 (a) and 13 (b) are second explanatory diagrams of the beam diameter BD on the lens surface in the third and fourth embodiments. Fig. 14 shows another embodiment of the plano-convex lens according to the third and fourth embodiments. FIG. 15 is a first calculation example of the radius of curvature of the third and fourth embodiments. FIG. 16 is a second calculation example of the curvature radius of the third and fourth embodiments. FIG. 17 shows an example of a plano-convex lens according to the fifth embodiment. FIG. 18 shows a configuration example of an optical fiber matrix module according to the sixth embodiment. FIG. 19 is an explanatory diagram of the optical systems according to the fifth and sixth embodiments. FIG. 20 is an explanatory view of aspherical shapes of the fifth and sixth embodiments. Fig. 21 shows an example of parameters in the fifth and sixth embodiments. FIG. 22 shows an example of a plano-convex lens according to the seventh embodiment. FIG. 23 shows a configuration example of an optical fiber matrix module according to the eighth embodiment. FIG. 24 is an explanatory diagram of the optical systems of the seventh and eighth embodiments. FIG. 25 is a first calculation example of the radius of curvature of the seventh and eighth embodiments. Fig. 26 is a second example of calculation of the radius of curvature of the seventh and eighth embodiments. Fig. 27 shows an example of a fiber matrix module according to a ninth embodiment. Fig. 28 shows an example of a light receiving module according to the ninth embodiment. FIG. 29 shows an example of an optical fiber matrix module according to the tenth embodiment. Fig. 30 shows an example of a light receiving module according to the tenth embodiment. FIG. 31 shows an example of a connection surface of the optical fiber matrix according to the eleventh embodiment as viewed from the z direction. FIG. 32 shows an example of the configuration of the light receiving module according to the eleventh embodiment when viewed from the x direction. FIG. 33 shows an example of an enlarged view of the optical fiber matrix and the lens matrix in the ninth embodiment. FIG. 34 shows another example of the optical fiber matrix module according to the ninth embodiment. FIG. 35 shows another example of the light receiving module according to the ninth embodiment.

Claims (12)

A plano-convex lens having a flat surface and a convex surface, and the convex surface has a first aspheric surface and a second aspherical surface, and the first aspheric surface and the second aspheric surface are arranged at the first position and the second end surface. The light emitted from the above-mentioned end faces of the two optical fibers at the position is parallel light, and when the parallel light incident from the first aspheric surface is reflected by the reflecting surface formed on the flat surface, the second aspheric surface converts the parallel light The light is focused on the second position. A plano-convex lens having a flat surface and a convex surface, and the convex surface has a first aspheric surface and a second aspherical surface, and the first aspheric surface and the second aspheric surface are arranged at the first position and the second end surface. The light incident from the above-mentioned end faces of the two optical fibers to the flat surface is parallel light, and is emitted in such a way that it is condensed to a point of the reflecting surface arranged at a predetermined specific distance from the first position and the second position. When the parallel light emitted from the first aspheric surface is reflected at the one point, the second aspheric surface condenses the parallel light at the second position. For example, the plano-convex lens of claim 1, wherein the first aspheric surface has a first convex surface, and the first convex surface is between an intersection of a straight line passing through the first position and perpendicular to the reflective surface and the convex surface, and a center of the convex surface It has a vertex, and the second aspheric surface has a second convex surface, and the second convex surface has an apex between an intersection of a straight line passing through the second position and perpendicular to the reflective surface and the convex surface, and a center of the convex surface. For example, the plano-convex lens of claim 2, wherein the first aspheric surface has a first convex surface, and the first convex surface is at the intersection of the line passing through the first position and perpendicular to the reflective surface and the convex surface, and the center of the convex surface. There is a vertex therebetween, and the second aspheric surface has a second convex surface having a vertex between an intersection of a straight line passing through the second position and perpendicular to the reflective surface and the convex surface, and a center of the convex surface. The plano-convex lens according to claim 3, wherein the convex surface is between the first convex surface and the second convex surface, and further includes a saddle portion for reducing a change in shape of a boundary between the first convex surface and the second convex surface. The plano-convex lens according to claim 4, wherein the convex surface is between the first convex surface and the second convex surface, and further includes a saddle portion for reducing a change in shape of a boundary between the first convex surface and the second convex surface. The plano-convex lens according to any one of claims 1 to 6, wherein a reflective portion is provided on the reflective surface, the reflective portion transmits a portion of the parallel light incident from the first aspheric surface, and a portion of the parallel light is directed toward The second aspheric reflection. An optical fiber matrix module comprising: a first lens matrix having a plurality of plano-convex lenses as in any one of claims 1 to 7, and the center axes of the plano-convex lenses are arranged side by side in a predetermined specific plane; and The optical fiber matrix has two optical fibers with respect to each of the plano-convex lenses, and an end face of each optical fiber is disposed at the first position or the second position of each of the plano-convex lenses. An optical fiber matrix module comprising: the optical fiber matrix module of claim 8; and a GRIN lens matrix having a plurality of GRIN lenses for each of the above-mentioned parallel light transmitted through the reflecting surface to be incident on a different of the above-mentioned GRIN lenses. One end, and each light emitted from the other end of the GRIN lens is focused at a point specified by each of the GRIN lenses. A light-receiving module includes: a fiber matrix module as claimed in claim 9; and a light-receiving element matrix that receives each light condensed by the above-mentioned GRIN lens matrix. An optical fiber matrix module comprising: the optical fiber matrix module according to claim 8; an optical component having a plurality of through holes for transmitting parallel light transmitted through the reflective surface for each of the parallels transmitted through the reflective surface Light is incident on one end of different through-holes, and parallel light passing through the through-holes is emitted from the other end of each through-hole; and a second lens matrix, each of which is emitted from the other end of the plurality of through-holes The light is condensed at a point prescribed by each of the aforementioned through holes. A light-receiving module includes: a fiber matrix module as claimed in claim 11; and a light-receiving element matrix that receives each light condensed by the second lens matrix.