WO2025238942A1 - Optical connection component - Google Patents

Abstract

Disclosed herein is an optical connection component comprising a GRIN lens component (92) that uses GRIN lenses (21) to connect, on a one-to-one basis, a first optical waveguide (31) arranged in a two-dimensional manner (23A) and a second optical waveguide (11) arranged in a one-dimensional manner (24B). A center axis (22) of a GRIN lens (21) connected to the first optical waveguide among the GRIN lenses provided to the GRIN lens component is offset from a center axis (23A) of the first optical waveguide, and a center axis (22) of a GRIN lens (21) connected to the second optical waveguide among the GRIN lenses provided to the GRIN lens component is offset from a center axis (24B) of the second optical waveguide. The respective GRIN lenses provided to the GRIN lens component are arranged so as to focus at the end surface of the first optical waveguide and the end surface of the second optical waveguide.

Description

Optical connection parts

This disclosure relates to optical connection components for achieving high-density optical packaging.

With the rise in internet traffic and the rapid use of artificial intelligence (AI), traffic within data centers has skyrocketed, making high-speed, large-capacity data transmission and reduced power consumption urgent issues. To address this, efforts are underway to develop a new type of optical transceiver that can replace pluggable modules, allowing for smaller size and higher speeds, in order to shorten wiring within the module and increase transmission speeds. In Non-Patent Document 1, optical modules are made smaller by mounting multiple optical transceivers on a single motherboard.

In Non-Patent Document 1, an optical fiber cable is connected to each optical transceiver, and each optical transceiver is connected to a single-mode fiber within the optical fiber cable. If single-mode fibers are arranged side by side as in Non-Patent Document 1, there is a problem in that the number of optical transceivers that can be mounted on a motherboard is limited by the outer diameter of the single-mode fiber.

Hideyuki Nasu, Satoshi Ide, Fumio Koyama, "Data Center Optical Interconnection Technology," Journal of the Institute of Electronics, Information and Communication Engineers, Vol. 106, No. 2, pp. 106-113

By using a multi-core fiber (MCF) that has multiple cores in a cladding with the same outer diameter as a single-mode fiber, it is possible to reduce the pitch of the optical waveguides in a photonic integrated circuit (PIC) installed in an optical transceiver in inverse proportion to the number of cores in the MCF. However, until now, there has been no small, simple optical connection component that can directly connect the two-dimensionally arranged cores of an MCF with the one-dimensionally arranged optical waveguides of a PIC.

To achieve the above objective, the optical connection component disclosed herein utilizes the optical path conversion function of a GRIN (Gradient Index) lens to enable direct connection by dimensionally converting two-dimensionally arranged optical waveguides and one-dimensionally arranged optical waveguides.

Specifically, the optical connecting component disclosed herein comprises a plurality of GRIN lenses that respectively connect a first plurality of focal points arranged at the vertices of a regular polygon and a second plurality of focal points arranged on a straight line, and the central axes of the plurality of GRIN lenses are offset from the first plurality of focal points and the second plurality of focal points. The first plurality of focal points are located at the core of the MCF, and the second plurality of focal points are located at the optical waveguide of the PIC.

The regular polygon may be a regular even-numbered polygon. In this embodiment, on a projection plane perpendicular to the central axis of the multiple GRIN lenses, the second multiple focusing points may be arranged on a straight line connecting any pair of opposing focusing points of the first multiple focusing points arranged on the regular even-numbered polygon. Furthermore, on a projection plane perpendicular to the central axis of the multiple GRIN lenses, the second multiple focusing points may be arranged on a straight line connecting the midpoints of any pair of opposite sides of the regular even-numbered polygon.

A corresponding pair of the first and second multiple focal points may be connected by a single GRIN lens. In this embodiment, the central axes of the GRIN lenses are positioned at the midpoint of a corresponding pair of the first and second multiple focal points on a projection plane perpendicular to the central axes of the GRIN lenses.

For example, when the centers of the vertices of the regular polygon are placed at the origin, the coordinates C _k (X, Y) of the central axis of the k-th GRIN lens among the plurality of GRIN lenses can be expressed by the following equations (4) and (5). Furthermore, when the regular polygon is a regular m-gon, where m is a natural number, and the centers of the vertices of the regular m-gon are placed at the origin, the coordinates C _k (X, Y) of the central axis of the k-th GRIN lens among the plurality of GRIN lenses can be expressed by the following equation (6).

The optical connection component disclosed herein may include an optical component in which optical waveguides are arranged two-dimensionally, and a GRIN lens component in which GRIN lenses are connected one-to-one to the optical waveguides. In this configuration, the central axis of a first end face of the GRIN lens that is connected to the first optical waveguide is offset from the central axis of the first optical waveguide, and light that is incident on the first end face of the GRIN lens from the end face of the first optical waveguide is focused in a straight line at the second end face of the GRIN lens that faces the first end face.

Specifically, the optical connection component disclosed herein includes a GRIN lens component that uses a GRIN lens to connect first optical waveguides arranged two-dimensionally with second optical waveguides arranged one-dimensionally on a one-to-one basis. Of the GRIN lenses included in the GRIN lens component, the central axis of the GRIN lens connected to the first optical waveguide is offset from the central axis of the first optical waveguide. Furthermore, of the GRIN lenses included in the GRIN lens component, the central axis of the GRIN lens connected to the second optical waveguide is offset from the central axis of the second optical waveguide. Each GRIN lens included in the GRIN lens component is positioned so as to form a focal point at the end face of the first optical waveguide and the end face of the second optical waveguide.

Light incident on a GRIN lens is guided along a sinusoidal curve due to the refractive index that is distributed in quadratic form on concentric circles around the central axis of the GRIN lens, and the lens length that describes one period is defined as one pitch length. The refractive index distribution constant g and one pitch length (P) are expressed by the following relationship:
(Equation 1)
P = 2π/g (1)

Therefore, when the lens length is 1/4P or 1/2P, (g*lens length) indicating the angle parameter of the trigonometric function of equation (1) is expressed by the following equations:
(Equation 2)
g*(1/4*2π/g)=1/2π
g*(1/2*2π/g)=π

The sum of the pitch lengths of the GRIN lenses connecting the first plurality of focal points and the second plurality of focal points is 1/2P or n+1/2P, where n is a natural number. For example, the GRIN lenses may be a pair of GRIN lenses with a pitch length of 1/4P or n+1/4P.

When the pair of GRIN lenses has a pitch length of 1/4P or n+1/4P, a spacer may be placed between the pair of GRIN lenses. The spacer may be made of air, glass, or liquid. In this form, the pair of GRIN lenses may be placed so that light emitted from the central axis of one of the pair of GRIN lenses passes through the central axis of the other of the pair of GRIN lenses.

The lens length of each GRIN lens included in the GRIN lens component may be 1/2 pitch or n+1/2 pitch, where n is a natural number.

The first optical waveguide and the second optical waveguide may be connected using two or more GRIN lenses.

Light that is perpendicularly incident from the first optical waveguide onto the GRIN lens provided in the GRIN lens component is output perpendicularly from the GRIN lens that is arranged on the second optical waveguide side of the GRIN lenses provided in the GRIN lens component. Furthermore, light that is perpendicularly incident from the second optical waveguide onto the GRIN lens provided in the GRIN lens component is output perpendicularly from the GRIN lens that is arranged on the first optical waveguide side of the GRIN lenses provided in the GRIN lens component.

The above disclosures may be combined to the greatest extent possible.

This disclosure makes it possible to connect to an optical transceiver at intervals smaller than the outer diameter of a single-mode fiber.

1 illustrates an example embodiment of an optical connecting component of the present disclosure. 10 shows an example of the configuration of a connection end face with a GRIN lens component in a PIC. An example of a CC cross section of an MCF is shown. 1 shows an example of a cross-sectional view of a GRIN lens component taken along line AA. 1 shows an example of a cross-sectional view of a GRIN lens component taken along line BB. 1 shows a state in which each GRIN lens provided in the GRIN lens component is projected onto the end face of the PIC. 1 shows an example of a ray trajectory from a core to an optical waveguide. 1 shows an example of mounting the optical connecting part of this embodiment on a motherboard. An example of conventional optical connection components mounted on a motherboard is shown. 1 illustrates an example embodiment of an optical connecting component of the present disclosure. An example of a DD cross-sectional view of the optical connecting part of this embodiment is shown. 10A and 10B are diagrams illustrating overlapping regions that occur in the optical connecting part of the present embodiment. 1 shows an example of a ray trajectory from a core to an optical waveguide. 1 shows an example of a ray trajectory from a core to an optical waveguide. An example of the ray trajectory when the pitch length of the GRIN lens is 1/2P is shown. An example of the ray trajectory when the pitch length of the GRIN lens is 1/4P is shown. 1 shows an example of a combination of GRIN lens components. 1 shows an example of a combination of GRIN lens components. 1 shows a configuration example of an optical connecting part according to the present disclosure. 10 shows an example of the configuration of the first and second plurality of light-focusing points. 10 shows an example of the configuration of the first and second plurality of light-focusing points. 10 shows an example of the configuration of the first and second plurality of light-focusing points. 10 shows an example of the configuration of the first and second plurality of light-focusing points. 10 shows an example of the configuration of the first and second plurality of light-focusing points. FIG. 2 is an explanatory diagram of the arrangement of a GRIN lens. 1 is an example of core coordinates. 10 is an example of an emission coordinate system. 1 is an example of the central axis coordinates of a GRIN lens. FIG. 2 is an explanatory diagram of the arrangement of a GRIN lens. 1 is an example of core coordinates. 10 is an example of an emission coordinate system. 1 is an example of the central axis coordinates of a GRIN lens.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, components with the same reference numerals in this specification and drawings are considered to be identical to each other.

(GRIN lens parts)
19 shows an example of the configuration of an optical connecting component according to the present disclosure. The optical connecting component according to the present disclosure is a GRIN lens component 92 in which a plurality of GRIN lenses 201 arranged in parallel are fixed to a capillary 202. The plurality of GRIN lenses 201 all have the same length, and the input and output end faces are perpendicular to the optical axis of the GRIN lenses 201.

The multiple GRIN lenses 201 each connect a first specific position on a first surface 203 of the GRIN lens component 92 and a second specific position on a second surface 204 of the GRIN lens component 92, each determined for each GRIN lens 201. Here, the first surface 203 and the second surface 204 are surfaces perpendicular to the central axis of the GRIN lens 201 and face each other. The central axis of the GRIN lens 201 is offset from the first specific position and the second specific position, so that light incident on the first specific position is focused at the second specific position, and light incident on the second specific position is focused at the first specific position. In this disclosure, the first specific position and the second specific position determined on the multiple GRIN lenses 201 are referred to as the first multiple focusing points and the second multiple focusing points.

The first plurality of focusing points are arranged at the vertices of a regular polygon on the first surface 203 where the end face of the GRIN lens 201 of the GRIN lens component 92 is exposed. The second plurality of focusing points are arranged in a straight line on the second surface 204 where the end face of the GRIN lens 201 of the GRIN lens component 92 is exposed.

Figures 20 and 21 show configuration examples of the first and second multiple focusing points. On a projection plane perpendicular to the central axis of the multiple GRIN lenses 201, the regular polygon is a regular even-sided polygon, with focusing points 211-214 indicated by black circles representing the first multiple focusing points, and focusing points 221-224 indicated by white circles representing the second multiple focusing points. Light incident on focusing point 211 is emitted from focusing point 221, light incident on focusing point 212 is emitted from focusing point 222, light incident on focusing point 213 is emitted from focusing point 223, and light incident on focusing point 214 is emitted from focusing point 224. Due to the bidirectionality of light, the incident and exit directions may be opposite. This also applies to the following examples.

In Figures 20 and 21, the focusing points 211 to 214 are arranged at the vertices of a regular rectangle. In the example of Figure 20, the focusing points 221 to 224 are arranged on a straight line 231 that connects the focusing points 211 and 214. The straight line 231 can be a straight line that connects any pair of opposing focusing points among the focusing points 211 to 214 that are arranged in a regular rectangle. In the example of Figure 21, the focusing points 221 to 224 are arranged on a straight line 232 that connects the midpoints of opposite sides of the regular rectangle. The straight line 232 can be a straight line that connects the midpoints of any pair of opposite sides of the regular rectangle.

Although FIGS. 20 and 21 show an example in which the second plurality of focusing points are arranged at the vertices of a regular square, the present disclosure is not limited to this. For example, the second plurality of focusing points may be arranged at the vertices of a regular hexagon as shown in FIGS. 22(a) and 23(a), or may be arranged at the vertices of a regular octagon as shown in FIGS. 22(b) and 23(b). In the example of FIGS. 22(a) and 23(a), light incident on focusing points 211 to 216 is emitted from focusing points 221 to 226, respectively. In the example of FIGS. 22(b) and 23(b), light incident on focusing points 211 to 218 is emitted from focusing points 221 to 228, respectively.

In the present disclosure, as shown in FIG. 22, the focal point 217 may be located at the center of a regular polygon. The example in FIG. 22 shows an example in which the focal point 227 is located at the same position as the focal point 217 on a projection plane perpendicular to the central axis of the multiple GRIN lenses 201. When the focal point 217 is located at the center of a regular polygon, the focal points 221 to 223, 217, and 224 to 226 may be arranged in order at equal intervals.

Note that the connection examples of the focusing points shown in Figures 20 to 23 are just examples, and any configuration can be adopted, such as adopting the connection shown in Figure 24 instead of Figure 22. Also, as shown in Figure 22, an MCF may have a core at the center of a regular polygon. In this configuration, a focusing point 217 may be added at the center of the regular polygon, and a GRIN lens may be placed at focusing point 217.

Furthermore, while Figure 19 shows an example in which there is one GRIN lens component 92, as described below, multiple GRIN lens components 92 may be stacked on top of each other. Below, we will explain an example in which the first multiple focal points are formed by a group of cores in an MCF, and the second multiple focal points are formed by a group of optical waveguides arranged one-dimensionally in a PIC.

(First arrangement of GRIN lens)
The arrangement of the GRIN lenses in the GRIN lens component 92 will be described with reference to Figure 25. The first plurality of focusing points arranged at the vertices of a regular m-polygon are called MCF coordinates, and the second plurality of focusing points are called emission coordinates. The center of the regular m-polygon is the origin of the XY coordinates, and the first core coordinate _C1 and the (m/2+1)th core coordinate Cm _/2+1 are on the Y axis. The center of the m emission coordinates is the origin, and the m emission coordinates are on the X axis, where m is a natural number.

The exit coordinate closest to the origin on the +X axis was designated as exit coordinate _O1 corresponding to core coordinate _C1 , and exit coordinates _Ok were associated with core coordinates _Ck in order of proximity to the origin. For core coordinates Cm _/2+1 and onwards, the exit coordinate closest to the origin on the -X axis was designated as exit coordinate Om _/2+1 corresponding to core coordinate Cm/2 ₊₁ , and exit coordinate Om _-1 farthest from the origin was associated with core coordinate Cm _-1 .

The distance R from the origin to each core is a known value. The angle θ between the line connecting the kth core C _k to the origin and the line connecting the adjacent core C _k+1 to the origin is expressed as 2π/m. Then, the following relationship holds:
(Equation 3)
R=(d/2)/sin(θ/2) (3)
However, the parameters are as follows:
d: MCF core spacing, i.e., the spacing between the vertices of the regular polygon.
p: the spacing between the exit coordinates, i.e., the spacing between the second plurality of focusing points.

From this relational expression, X(C) and Y(C) shown in Fig. 26 are obtained as the X and Y coordinates of the core coordinates, and X(O) and Y(O) shown in Fig. 27 are obtained as the X and Y coordinates of the emission coordinates. When the core coordinates and the emission coordinates are connected by only one GRIN lens 201, as shown in Fig. 25, the central axis of the GRIN lens 201 may be positioned at the center of the core coordinates and the emission coordinates on a projection plane perpendicular to the central axes of the multiple GRIN lenses 201. Therefore, the central axis coordinates _Gk (X,Y) of the GRIN lens are as shown in Fig. 28.

When k<m/2+1, the central axis coordinate G _k (X, Y) of the GRIN lens is obtained by the following equation.
(Equation 4)
X=(R*sin((k-1)θ)+(2k-1)*p)/2
Y=R*cos((k-1)θ)/2

Furthermore, when k>=m/2+1, the central axis coordinates G _k (X, Y) of the GRIN lens are obtained by the following equation.
(Equation 5)
X=(R*sin((k-1)θ)-(k-3-m/2)*p)/2
Y=R*cos((k-1)θ)/2

(Second arrangement of GRIN lens)
29, the arrangement of the GRIN lenses in the GRIN lens component 92 will be described. In this example, the output coordinates O _k are associated with the core coordinates C _k in order of proximity to the origin, so that the core coordinates arranged on the +Y axis side and the core coordinates arranged on the −Y axis side alternate.

In this arrangement, X(C) and Y(C) shown in Figure 30 are obtained as the X and Y coordinates of the core coordinates, and X(O) and Y(O) shown in Figure 31 are obtained as the X and Y coordinates of the emission coordinates. When the core coordinates and emission coordinates are connected by only one GRIN lens 201, as shown in Figure 25, the central axis of the GRIN lens 201 can be positioned at the center of the core coordinates and emission coordinates on a projection plane perpendicular to the central axes of the multiple GRIN lenses 201. Therefore, the central axis coordinate Gk(X,Y) of the GRIN lens is as shown in Figure 32.

The central axis coordinates G _k (X, Y) of the GRIN lens are obtained by the following equation.

Therefore, the central axis coordinate _Gk (X,Y) of the GRIN lens can be obtained using the core coordinate _Ck and the exit coordinate _Ok . That is, the central axis coordinate _Gk (X,Y) of the GRIN lens is a specific position determined by the combination of the core coordinate _Ck and the exit coordinate _Ok . Therefore, by employing a GRIN lens component 92 in which the central axis coordinate _Gk (X,Y) of the GRIN lens is located at a position corresponding to the combination of the MCF and the PIC, the MCF and the PIC can be directly connected.

In this embodiment, the central axis coordinate _Gk (X,Y) of the GRIN lens has been described using the combination of the core coordinate _Ck and the exit coordinate _Ok shown in Fig. 25, but as is clear from the examples of Fig. 22 and Fig. 24, the combination of the core coordinate _Ck and the exit coordinate _Ok is not limited to this. Therefore, the central axis coordinate _Gk (X,Y) of the GRIN lens can be placed at any position according to the combination of the core coordinate _Ck and the exit coordinate _Ok .

(First embodiment)
1 shows an embodiment of an optical connecting part according to the present disclosure. In this embodiment, an example is shown in which the "first optical waveguide" is a core 31 provided in an MCF 93, and the "second optical waveguide" is an optical waveguide 11 provided in a PIC 91. The cores 31 are arranged two-dimensionally, and the optical waveguides 11 are arranged one-dimensionally. The optical connecting part 92 of this embodiment connects the cores 31 and the optical waveguides 11 one-to-one.

In this embodiment, an example is shown in which the optical connecting part is equipped with an MCF 93 and a GRIN lens part 92A. Here, the # symbols in the figure indicate numbers for identifying the components. For example, reference numeral 11#1 indicates the first optical waveguide 11, reference numeral 11#2 indicates the second optical waveguide 11, reference numeral 11#3 indicates the third optical waveguide 11, and reference numeral 11#4 indicates the fourth optical waveguide 11. Figure 1 also shows an example in which the optical connecting part 92 is equipped with GRIN lens parts 92A and 92B. The GRIN lens provided in the GRIN lens part 92A is indicated by reference numeral 21A, and the GRIN lens provided in the GRIN lens part 92B is indicated by reference numeral 21B.

In this embodiment, an example is shown in which a GRIN lens component 92B is provided in which GRIN lenses 21A#1-21A#4 are connected to GRIN lenses 21B#1-21B#4 in a one-to-one relationship, and the GRIN lens component is made up of GRIN lens components 92A and 92B.

The central axes of the first end faces of GRIN lenses 21A#1-21A#4 that are connected to cores 31#1-31#4 are offset from the central axes of cores 31#1-31#4. Light that enters the first end faces of GRIN lenses 21A#1-21A#4 from the end faces of cores 31#1-31#4 is focused in a straight line at the second end faces of GRIN lenses 21B#1-21B#4 that face the first end faces.

Of the GRIN lenses 21 provided in the GRIN lens component 92, the GRIN lens 21 arranged closest to the core 31 is arranged so that the center of the core 31 is offset from the central axis of the GRIN lens 21. Of the GRIN lenses 21 provided in the GRIN lens component 92, the GRIN lens 21 arranged closest to the optical waveguide 11 is arranged so that the center of the optical waveguide 11 is offset from the central axis of the GRIN lens 21.

Furthermore, each GRIN lens 21 provided in the GRIN lens component 92 is arranged so as to focus at the end face of the core 31 and the end face of the optical waveguide 11. For example, light perpendicularly incident from the core 31 onto the GRIN lens 21 provided in the GRIN lens component 92 is emitted from the GRIN lens 21 provided in the GRIN lens component 92 so as to focus at the end face of the optical waveguide 11. Light perpendicularly incident from the optical waveguide 11 onto the GRIN lens 21 provided in the GRIN lens component 92 is emitted from the GRIN lens 21 provided in the GRIN lens component 92 so as to focus at the end face of the core 31.

In this embodiment, an example is shown in which the core 31 and the optical waveguide 11 are connected using two GRIN lenses 21. Specifically, the optical connection component 92 includes GRIN lens components 92A and 92B. The incident end face of the GRIN lens component 92A is connected to the MCF 93, and the exit end face of the GRIN lens component 92B is connected to the PIC (Photonic Integrated Circuit) 91.

In this embodiment, an example is shown in which the GRIN lens component 92B is connected to four optical waveguides 11#1, 11#2, 11#3, and 11#4 provided in the PIC 91. The optical waveguides 11#1, 11#2, 11#3, and 11#4 can be any optical paths provided in the photonic integrated circuit. For example, the optical waveguides 11#1, 11#2, 11#3, and 11#4 may be connected to an optical transceiver.

Figure 2 shows an example of the configuration of the connection end face of PIC91 with GRIN lens component 92B. The end faces of optical waveguides 11#1, 11#2, 11#3, and 11#4 are arranged in a straight line on the end face of PIC91.

3 shows an example of a cross-sectional view of the MCF 93 taken along the line CC in FIG. 1. The MCF 93 of this embodiment includes four cores 31#1, 31#2, 31#3, and 31#4 in the cladding 33. In this embodiment, the cores 31#1, 31#2, 31#3, and 31#4 are arranged on concentric circles centered on the central axis C93 of the MCF ₉₃ .

Figure 4 shows an example of a cross-sectional view of GRIN lens component 92A taken along line A-A in Figure 1. GRIN lens component 92A has four GRIN lenses 21A#1, 21A#2, 21A#3, and 21A#4. Figure 5 shows an example of a cross-sectional view of GRIN lens component 92B taken along line B-B in Figure 1. GRIN lens component 92B has four GRIN lenses 21B#1, 21B#2, 21B#3, and 21B#4. GRIN lenses 21A#1, 21A#2, 21A#3, and 21A#4 are held in capillary 25A, and GRIN lenses 21B#1, 21B#2, 21B#3, and 21B#4 are held in capillary 25B.

The lens lengths _L21A and _L21B of the GRIN lenses provided in the GRIN lens components 92A and 92B are ½ pitch or n+½ pitch, where n is a positive number and one period of the sinusoidal optical path of the GRIN lens is 1 pitch. Using these eight GRIN lenses, light emitted from the cores 31#1, 31#2, 31#3, and 31#4 is made incident on the optical waveguides 11#1, 11#2, 11#3, and 11#4.

GRIN lenses 21A#1 and 21B#1 guide light from core 31#1 to optical waveguide 11#1. GRIN lenses 21A#2 and 21B#2 guide light from core 31#2 to optical waveguide 11#2. GRIN lenses 21A#3 and 21B#3 guide light from core 31#3 to optical waveguide 11#3. GRIN lenses 21A#4 and 21B#4 guide light from core 31#4 to optical waveguide 11#4.

Figure 6 shows the GRIN lenses of GRIN lens components 92A and 92B projected onto the end face of PIC 91. Figure 7 shows an example of a ray trajectory from core 31#2 to optical waveguide 11#2. Light incident from core 31#2 to position 23A#2 of GRIN lens 21A#2 is incident on GRIN lens 21B#2 at position 24A#2, which is point-symmetric about central axis 22A#2 of GRIN lens 21A#2. Light incident on position 23B#2 of GRIN lens 21B#2 is emitted from position 24B#2, which is point-symmetric about central axis 22B#2 of GRIN lens 21B#2.

In this embodiment, the GRIN lenses 21A#2 and 21B#2 are arranged so that the position 24B#2 coincides with the optical waveguide 11#2 on the surface _LH . Therefore, light incident on the core 31#2 is output to the optical waveguide 11#2 via the GRIN lenses 21A#2 and 21B#2. Similarly, the light output from the other cores 31#1, 31#3, and 31#4 is output to the optical waveguides 11#1, 11#3, and 11#4.

Therefore, the GRIN lens components 92A and 92B of this embodiment can connect the cores 31#1, 31#2, 31#3, and 31#4 of the MCF 93 to the optical waveguides 11#1, 11#2, 11#3, and 11#4 of the PIC 91, respectively.

Figure 8 shows an example of mounting the optical connection components of this embodiment on a motherboard. 4 x 4 PICs 91 are arranged on each side of the motherboard 81, with an ASIC (Application Specific Integrated Circuit) 83 mounted in the center. Each PIC 91 is equipped with an optical transceiver and sends and receives optical signals according to instructions from the ASIC 83.

Figure 9 shows an example of conventional optical connection components mounted on a motherboard. This example shows 4 x 4 PICs 91 arranged on each side of a motherboard 81, with an ASIC 83 mounted in the center. The PICs 91 are connected to an SMF 73 using optical connectors 72. For this reason, the number of PICs 91 that could be mounted on one side of the motherboard 81 was limited to the number of optical connectors 72 that could be mounted on one side of the motherboard 81.

In this embodiment, as shown in Figure 8, one MCF 93 is connected instead of four SMFs 73. This allows the pitch of the PIC 91 to be reduced, enabling high-density packaging of PICs 91 equipped with optical transceivers.

Furthermore, in this embodiment, the optical connection component 92 is connected to the PIC 91 using adhesive or the like so that no gaps are created, enabling a stable optical connection even in a liquid refrigerant.

Second Embodiment
10 shows an example embodiment of an optical connecting component according to the present disclosure. In the first embodiment, the optical connecting component 92 is configured using two GRIN lens components 92A and 92B, but the optical connecting component according to the present disclosure can be configured using any number of GRIN lens components, one or more. As an example, in this embodiment, the optical connecting component 92 is configured using one GRIN lens component.

FIG. 11 shows an example of a D-D cross-sectional view of an optical connecting part 92 of this embodiment. The optical connecting part 92 includes four GRIN lenses 21#1, 21#2, 21#3, and 21#4. The lens lengths _L21A and _L21B of the GRIN lenses 21#1, 21#2, 21#3, and 21#4 have a periodic length of 1/2 the pitch of a sine wave. Using these four GRIN lenses, light incident from the cores 31#1, 31#2, 31#3, and 31#4 shown in FIG. 3 is output to the optical waveguides 11#1, 11#2, 11#3, and 11#4 shown in FIG. 2.

GRIN lens 21#1 guides light from core 31#1 to optical waveguide 11#1. GRIN lens 21#2 guides light from core 31#2 to optical waveguide 11#2. GRIN lens 21#3 guides light from core 31#3 to optical waveguide 11#3. GRIN lens 21#4 guides light from core 31#4 to optical waveguide 11#4.

In this embodiment, as shown in Figure 12, there are regions where the GRIN lenses overlap. For example, region R1 at the boundary between GRIN lenses 21#1 and 21#2, region R2 at the boundary between GRIN lenses 21#2 and 21#3, and region R3 at the boundary between GRIN lenses 21#3 and 21#4 overlap. These regions R1, R2, and R3 can be separated by straight lines connecting the intersections of region R1, as shown in Figure 11.

When manufacturing this embodiment, the base material of GRIN lenses 21#1, 21#2, 21#3, and 21#4 is cut linearly at the boundary regions between the GRIN lenses, and these are then stretched into the shape shown in Figure 11. At this time, a capillary with through holes formed to match the arrangement of GRIN lenses 21#1, 21#2, 21#3, and 21#4 may be prepared, and the base material of GRIN lenses 21#1, 21#2, 21#3, and 21#4 may be placed in the through holes of this capillary and then stretched.

In this embodiment, an optical connection component can be constructed using a single GRIN lens component. This allows the distance from the MCF 93 to the PIC 91 to be shorter than in the first embodiment. Therefore, by adopting this embodiment, the optical module can be further miniaturized.

(Third embodiment)
In this embodiment, the incident position and the exit position when the pitch length of the GRIN lens 21 is ½P or n+½P will be described with reference to Fig. 15. The ray trajectory equation of the GRIN lens 21 is expressed as follows.
where the parameters are as follows:
_r1 : Output position _r0 : Input position (height)
θ ₀ : input angle θ ₁ : output angle to air g: refractive index distribution constant [mm ⁻¹ ]
z: lens length

When light incident at an input angle of 0 deg. (normal incidence) and an input position of Δ is guided through the GRIN lens 21 having a pitch length of ½P (i.e., π), the following is obtained from equations (11) and (12):
(Equation 13)
r ₁ =-1*Δ+[0]
θ ₁ = [0] + θ ₀
Therefore, the exit positions are symmetrical with respect to the central axis of the GRIN lens 21 at the same distance Δ, and the exit angle is 0 degrees, the same as the incident angle.

Therefore, when light incident at a distance Δ from the central axis of the GRIN lens 21 has a pitch length of 1/2P, i.e., when the lens length z = P/(2 * g), it emerges perpendicularly from the opposite surface of the GRIN lens 21 at a position shifted by 2 * Δ from the incident position.

Furthermore, if multiple GRIN lenses 21 are connected in the axial direction and the lens input position is shifted by Δ1, Δ2... Δn relative to the central axis of each GRIN lens 21, the output position will also be shifted by Δ1, Δ2... Δn from the centrally symmetric position relative to the central axis of each GRIN lens 21. Therefore, each time light is guided through a GRIN lens 21, it can be shifted by 2*Δ1, 2*Δ2... 2*Δn, and by setting the shift direction for each GRIN lens 21, the final output position can be set to any position. Therefore, by similarly stacking GRIN lenses 21 corresponding to multiple incident light beams, it is possible to convert two-dimensional input light into one-dimensional output light.

(Fourth embodiment)
In this embodiment, the incident position and the exit position when the pitch length of the GRIN lenses 21A and 21B is ¼P or n+¼P will be described with reference to Fig. 16. In this embodiment, an example is shown in which a spacer 94 having a thickness L and made of air is disposed between the GRIN lenses 21A and 21B. The spacer 94 may alternatively be made of glass or liquid.

When light is incident on the incident-side GRIN lens 21A at an input angle of 0 deg. (normal incidence) and an input position of Δ, and is guided through the incident-side GRIN lens 21A having a pitch length of ¼P (i.e., π/2), the exit position _r1 of the incident-side GRIN lens 21A and the exit angle _θ1 from the incident-side GRIN lens 21A are determined as follows from equations (11) and (12):
(Number 15)
r ₁ = [0] + [0]
θ ₁ =-n ₀ *g*Δ+[0]
Therefore, the exit position of the incident-side GRIN lens 21A is the GRIN lens axis of the incident-side GRIN lens 21A, and the exit angle θ ₁ from the incident-side GRIN lens 21A is −n ₀ *g*Δ.

Next, when the distance between the central axes of the incident-side GRIN lens 21A and the exit-side GRIN lens 21B is D and the distance between the GRIN lenses is L, the exit-side GRIN lens 92B is set so as to satisfy the following equation:
(Equation 16)
D/L=tan(θ1)
=tan(-n ₀ *g*Δ)

In this case, when light is incident on the central axis of the output-side GRIN lens 21B, which has a pitch length of 1/4P, at an angle of −n ₀ *g*Δ and is guided through the GRIN lens 21B, which has a pitch length of 1/4P (i.e., π/2), it becomes as follows from equations (11) and (12):
(Equation 17)
r ₁ = [0] + Δ
θ ₁ = [0] + [0]

That is, the pair of GRIN lenses 21A and 21B are arranged so that light emitted from the central axis of GRIN lens 21A passes through the central axis of GRIN lens 21B. As a result, light incident on the central axis of the exit-side GRIN lens, which has a pitch length of 1/4P, at an angle -n ₀ *g*Δ is emitted at a right angle at a position Δ away from the central axis of the GRIN lens, according to equations (11) and (12).

Therefore, the shift amount when a pair of GRIN lenses with a pitch length of 1/4P is guided is expressed as follows:
(Number 18)
2*Δ+D

In this way, by stacking multiple sets of 1/4P GRIN lenses, the shift amount can be selected for each stage, just as with 1/2P GRIN lenses. Furthermore, in this embodiment, by setting the shift direction for each lens, the final exit position can be set to any position, making it easy to output light that is incident two-dimensionally in one dimension.

Fifth Embodiment
In this embodiment, a combination of GRIN lens components will be described. It is possible to combine a 1/2P GRIN lens with a 1/4P GRIN lens. For example, as shown in FIGS. 17 and 18 , when GRIN lenses 51, 52, 53, and 54 are connected in this order from an MCF 93, the lens lengths of the GRIN lenses 51 and 52 may be 1/2P, and the lens lengths of the GRIN lenses 53 and 54 may be 1/4P.

In the configuration shown in Figure 17, an optical connection component is fabricated in which GRIN lenses 51, 52, and 53 are pre-connected to MCF 93, and GRIN lens 54 is pre-connected to PIC 91. This allows PIC 91 to be connected by connecting GRIN lens 54 and GRIN lens 53. Here, GRIN lens 54 and GRIN lens 53 should be connected so that the central axes of the GRIN lenses are aligned.

In Figure 18, a spacer 94 is placed between the GRIN lens 54 and the GRIN lens 53. In this configuration, the distance L between the GRIN lenses 54 and 53 can be adjusted using the thickness of the spacer 94. For this configuration, an optical connection component may be fabricated in which the GRIN lenses 51, 52, 53 and the spacer 94 are pre-connected to the MCF 93, or the GRIN lens 54 and the spacer 94 may be pre-connected to the PIC 91.

(Other embodiments)
The 1/2 pitch GRIN lens 21 used in the above-described embodiment may be configured using a 1/4 pitch or n+1/4 pitch. For example, the GRIN lens components 92A and 92B shown in FIG. 7 may be configured using two GRIN lenses 41A#2 and 41B#2 having a lens length of 1/4 pitch, as shown in FIG. 13. In this configuration, a spacer 94 may be provided between the two GRIN lenses 41A#2 and 41B#2 having a lens length of 1/4 pitch, as shown in FIG. 14. By adopting such a configuration for the GRIN lens 21A shown in FIG. 6, the shift amount can be increased.

The characteristics of the two GRIN lenses with a lens length of 1/4 pitch may be the same or different. For example, a 1/4 pitch lens with different GRIN lens characteristics is provided at the tip of these optical connection components, and a GRIN lens with an equivalent 1/4 pitch is attached to the optical waveguide side that is connected to this. Because the two GRIN lenses have different characteristics, mode conversion and connection can be performed simultaneously using a common optical component. By adopting this configuration, it is possible to omit the mode conversion component, thereby significantly miniaturizing the configuration from the MCF 93 to the PIC 91. Therefore, this embodiment enables high-density packaging of the PIC 91 and enables the optical module to be miniaturized.

In the above embodiment, an example was shown in which the two-dimensionally arranged first optical waveguides were cores 31 of MCF 93 and the one-dimensionally arranged second optical waveguides were PIC 91, but the present disclosure is not limited to this. For example, the first optical waveguides may be two-dimensionally arranged optical fiber arrays or multi-core connectors, and the second optical waveguides may be one-dimensionally arranged optical fiber arrays or multi-core connectors.

Furthermore, the optical connecting component of the present disclosure may include all or part of the optical connecting component 92 and the MCF 93, may include all or part of the optical connecting component 92 and the PIC 91, or may include all of the optical connecting component 92, the MCF 93, and the PIC 91.

11#1, 11#2, 11#3, 11#4: Optical waveguides 21, 21#1, 21#2, 21#3, 21#4, 21A#1, 21A#2, 21A#3, 21A#4, 21B#1, 21B#2, 21B#3, 21B#4, 41A#2, 41B#2, 51, 52, 53, 54, 201: GRIN lenses 22#1, 22#2, 22#3, 22#4: Central axes 23#1, 23#2, 23#3, 23#4, 24#1, 24#2, 24#3, 24#4: Positions 31, 31#1, 31#2, 31#3, 31#4: Core 72: Optical connector 73: SMF
81: Motherboard 83: ASIC
91:PIC
92: Optical connection parts 92A, 92B: GRIN lens parts 93: MCF
94: Spacer 202: Capillary 203: First surface 204: Second surface 211, 212, 213, 214, 215, 216, 217, 218: First plurality of light-converging points 221, 222, 223, 224, 225, 226, 227, 228: Second plurality of light-converging points 321, 232: Straight lines

Claims (15)

a plurality of GRIN lenses respectively connecting a first plurality of focusing points arranged at vertices of a regular polygon and a second plurality of focusing points arranged on a straight line;
the central axes of the plurality of GRIN lenses are offset from the first plurality of focal points and the second plurality of focal points;
Optical connection parts. the regular polygon is a regular even-sided polygon,
In a projection plane perpendicular to the central axes of the plurality of GRIN lenses, the second plurality of focusing points are arranged on a straight line connecting any one pair of opposing focusing points among the first plurality of focusing points arranged in the regular even polygon.
The optical connecting part according to claim 1 . the regular polygon is a regular even-sided polygon,
In a projection plane perpendicular to the central axes of the plurality of GRIN lenses, the second plurality of light-converging points are arranged on a straight line connecting the midpoints of any pair of opposite sides of the regular even-numbered polygon.
The optical connecting part according to claim 1 . On a projection plane perpendicular to the central axes of the plurality of GRIN lenses, the central axes of the plurality of GRIN lenses are disposed at midpoints of corresponding pairs of the first plurality of focusing points and the second plurality of focusing points.
The optical connecting part according to claim 1 . When the centers of the vertices of the regular polygon are located at the origin, the coordinates C _k (X, Y) of the central axis of the k-th GRIN lens among the plurality of GRIN lenses are expressed by the following equation:
The optical connecting part according to claim 4 .
X=(R*sin((k-1)θ)+(2k-1)*p)/2
Y=R*cos((k-1)θ)/2
However, the parameters are as follows:
R: The distance from the origin to a vertex of the regular polygon.
θ: An angle formed by a line connecting the kth focusing point among the first plurality of focusing points and the origin and a line connecting a focusing point adjacent to the kth focusing point among the first plurality of focusing points and the origin. When m is a natural number, the regular polygon is a regular m-gon, and when the centers of the vertices of the regular m-gon are placed at the origin, the coordinates C _k (X, Y) of the central axis of the k-th GRIN lens among the plurality of GRIN lenses are expressed by the following equation:
The optical connecting part according to claim 4 .
However, the parameters are as follows:
R: The distance from the origin to the vertex of the regular m-gon.
θ: An angle formed by a line connecting the kth focusing point among the first plurality of focusing points and the origin and a line connecting a focusing point adjacent to the kth focusing point among the first plurality of focusing points and the origin.
p: the spacing between the second plurality of focusing points. a sum of pitch lengths of the GRIN lens connecting the first plurality of focal points and the second plurality of focal points is ½P or n+½P, where n is a natural number;
The optical connecting part according to claim 1 . The GRIN lens is a pair of GRIN lenses having a pitch length of ¼P or n+¼P.
The optical connecting part according to claim 7 . a spacer is disposed between the pair of GRIN lenses;
the pair of GRIN lenses are arranged so that light emitted from a central axis of one of the pair of GRIN lenses passes through a central axis of the other of the pair of GRIN lenses;
The optical connecting part according to claim 8 . The spacer is composed of air, glass, or liquid.
The optical connecting part according to claim 9 . a multicore fiber having cores arranged at the vertices of the regular polygon;
the multi-core fiber has cores connected to the first plurality of light-focusing points;
The optical connecting part according to claim 1 . a GRIN lens component that connects first optical waveguides arranged two-dimensionally and second optical waveguides arranged one-dimensionally on a one-to-one basis using a GRIN lens;
a central axis of a GRIN lens connected to the first optical waveguide among the GRIN lenses included in the GRIN lens component is misaligned with a central axis of the first optical waveguide;
a central axis of a GRIN lens connected to the second optical waveguide among the GRIN lenses included in the GRIN lens component is misaligned with a central axis of the second optical waveguide;
Each GRIN lens included in the GRIN lens component is arranged so as to form a focal point at an end face of the first optical waveguide and an end face of the second optical waveguide.
Optical connection parts. The lens length of each GRIN lens included in the GRIN lens component is ½ pitch or n+½ pitch, where n is a natural number.
The optical connecting part according to claim 12. the first optical waveguide and the second optical waveguide are connected using two or more GRIN lenses;
The optical connecting part according to claim 12. light that is perpendicularly incident from the first optical waveguide onto a GRIN lens included in the GRIN lens component is perpendicularly output from a GRIN lens that is arranged on the second optical waveguide side of the GRIN lenses included in the GRIN lens component,
light perpendicularly incident from the second optical waveguide onto a GRIN lens included in the GRIN lens component is perpendicularly output from a GRIN lens that is arranged on the first optical waveguide side among the GRIN lenses included in the GRIN lens component;
The optical connecting part according to claim 12.