WO2012051769A1 - Photonic crystal multi-port circulator - Google Patents

Abstract

A photonic crystal multi-port circulator is disclosed. The photonic crystal main body consists of first air columns symmetrically arranged in a triangle pattern in the medium material; which comprises at least six magneto-optical cavities, the centers of the magneto-optical cavities are connected by lines in sequence to form one regular hexagon or a plurality of cascaded regular hexagons. At least six waveguides are symmetrically constructed at the periphery of one regular hexagon or the peripheries of a plurality of cascaded regular hexagons. Two second air columns, both of which have smaller diameter than the first air column, are arranged between the adjacent magneto-optical cavities and between the adjacent magneto-optical cavity and the waveguide; third air columns and fourth air columns with periodically increasing diameters are arranged around each magneto-optical cavity as the centre; the light is input from any waveguide and output from another spaced waveguide, and the other waveguides are optically isolated to form a one-way optical circulation transmission. The invention has compact structure and can perform the optical circulation in wider frequency band range; and the photonic crystal device integration can guide and isolate crosstalk light signals.

Description

 Photonic crystal multiport circulator

Technical field

 The present invention relates to the field of photonic crystal devices and magneto-optical technologies, and more particularly to a photonic crystal six-port circulator and an extended circulator thereof. Background technique

 Optical circulators are important optical devices with anti-jamming effects in integrated optics. The optical circulator can form a unidirectional circular transmission of light between multiple ports, allowing the incident signal to pass smoothly and the reflected signal to be isolated. This feature can greatly reduce the crosstalk of reflected light between devices in the integrated optical path, which is very beneficial to improve the stability of the system. Conventional optical circulators are mainly based on a bulk structure of magneto-optical materials, which has the disadvantage of being bulky and difficult to integrate with other devices. These disadvantages largely limit their application in the integration of next-generation optical devices. The concept of photonic crystal and its research and development have opened up new ideas and new methods for the realization of miniaturization and easy integration of magneto-optical circulators.

 A photonic crystal is an artificial material whose dielectric constant is arranged in a periodic or quasi-periodic manner in space. It can make light waves in a certain frequency band not propagate in it, thereby forming a photonic band gap. The introduction of defects in a complete photonic crystal enables the guidance and control of photons as well as the manipulation of electrons in semiconductor materials. Photonic crystal devices are superior to many traditional optics, such as small size, superior performance, and ease of integration, making them one of the most promising photonic devices for all-optical integrated chips.

As the integration of photonic crystal devices increases, the mutual interference between devices in the optical path becomes more and more prominent. If the interference signal cannot be effectively eliminated or suppressed, it will affect the working performance and integration effect of the overall optical path to a large extent. Anti-jamming devices that optimize optical path performance are critical. The magneto-optical circulator characterized by non-reciprocity uses the magneto-optic effect to realize the irreversible single-direction circular transmission of light between different ports, which can successfully guide or isolate the optical interference signal, which is very effective. Optical path anti-jamming device. Based on the photonic crystal structure of the magneto-optical circulator, a three-port, four-port structure based on a single photonic crystal magneto-optical cavity has been proposed, but a four-port photonic crystal circulator and its design have not yet appeared. Photonic crystal magneto-optical circulators with multi-port (more than four ports) are invaluable in improving the anti-interference and stability of optical paths in complex integrated systems, and are essential for large-scale integrated optical paths of photonic crystals. Basic component. Summary of the invention

 The technical problem to be solved by the present invention is to provide a photonic crystal multi-port circulator, which can obtain high-efficiency transmission and high isolation of different ports, and realize single-directional loop function of optical signals between multiple ports to solve complex photons. The optical signal crosstalk problem in the crystal integrated optical path.

 The technical solution adopted by the present invention to solve the technical problem thereof is: a photonic crystal multi-port circulator, wherein the photonic crystal body is composed of a first air column symmetrically distributed in a dielectric material, and includes at least six magneto-optical cavities. The center of the magneto-optical cavity is sequentially connected to form a regular hexagon or a plurality of cascading regular hexagons, and at least six waveguides are symmetrically constructed in a regular hexagon or a plurality of cascading regular hexagonal periphery, each The waveguide is formed by filling a column of the first air column with the dielectric material, and two second air columns having a diameter smaller than the diameter of the first air column are disposed between the adjacent magneto-optical cavities and between the adjacent magneto-optical cavities and the waveguide, A third air column and a fourth air column with increasing diameters of two periods are disposed around each of the magneto-optical chambers, and a diameter of the fourth air column is larger than a diameter of the third air column, and a diameter of the third air column is More than the diameter of the first air column, light is input from any of the waveguides and output from the next adjacent waveguide, and the remaining waveguides are in an optically isolated state to form a unidirectional optical ring transmission.

 In the present invention, an eight-port circulator having ten magneto-optical cavities is arranged, the centers of the ten magneto-optical cavities are sequentially connected to form two cascaded regular hexagons, and the two hexagonal positive hexagons Eight waveguides are symmetrically constructed around the shape.

In the present invention, a nine-port circulator having thirteen magneto-optical cavities is included, said thirteen magnetrons The centers of the cavities are sequentially connected to form three cascaded regular hexagons, and nine waveguides are symmetrically constructed on the periphery of the three cascaded regular hexagons.

 In the present invention, a ten-port circulator having sixteen magneto-optical cavities is included, the centers of the sixteen magneto-optical cavities being sequentially connected to form four cascaded regular hexagons, in which the four cascades Ten waveguides are symmetrically constructed around the regular hexagon.

 In the present invention, a twelve-port circulator having twenty-four magneto-optical cavities is included, and the centers of the twenty-four magneto-optical cavities are sequentially connected to form seven cascaded regular hexagons, in the seven Twelve waveguides are symmetrically constructed around the cascading regular hexagon.

 In the present invention, each of the magneto-optical cavities comprises a magneto-optical material column and six first air columns distributed around the magneto-optical material column, the magneto-optical material column being filled to a first air column. The magneto-optical material is formed by applying a magnetic field in a direction parallel to the axis of the first air column.

 In the present invention, when the distance between the adjacent magneto-optical cavities is the same, the circulator has a function of the unidirectional optical ring line, and the "lattice constant of the photonic crystal," is a natural number greater than or equal to 5, preferably , η is a natural number greater than or equal to 5 and less than or equal to 10.

 In the present invention, the length of the waveguide is at least three of the photonic crystal lattice constants, and the length of the waveguide is increased, and the unidirectional optical ring function of the circulator is unchanged.

 In the present invention, the dielectric material may be a gallium nitride dielectric material, and the magneto-optical material filling the first air column may be yttrium iron garnet.

 In the present invention, the first to fourth air columns and the column of the magneto-optical material distributed in the dielectric material may have a circular, quadrangular, pentagonal or hexagonal cross section.

 In the present invention, the first to fourth air columns in the photonic crystal are dielectric columns of a low refractive index material.

Compared with the prior art, the invention utilizes the annular cascading mode and the optical rotation effect of the magneto-optical cavity to realize single-direction circular transmission of optical signals between multiple ports, and provides high-efficiency optical transmission and height between multiple ports. Optical isolation, the photonic crystal multi-port circulator of the invention can simultaneously guide or isolate light reflection between multiple devices, effectively solve the optical signal crosstalk problem in the integrated photonic crystal integrated optical path; further, the photonic crystal multi-port circulator of the invention Compact and easy to integrate with other photonic crystal devices. DRAWINGS

 1 is a schematic view showing the structure of a dielectric substrate-air column type photonic crystal six-port circulator in a photonic crystal multi-port circulator according to a first embodiment of the present invention.

 2 is a schematic structural view of a dielectric substrate-air column type photonic crystal six-port circulator according to a first embodiment of the photonic crystal multi-port circulator of the present invention.

₃ is a schematic diagram of a spectrum of a photonic crystal multi-port circulator according to a first embodiment of the present invention, wherein light is incident from the waveguide port 61, the solid line corresponds to the optical power of the waveguide port 62, and the dashed line corresponds to the optical power of the waveguide port 63, and the dotted line corresponds to the waveguide. The optical power of the port 64 or 65, the dashed-dotted line corresponds to the optical power of the waveguide port 66, and the dashed-double dotted line corresponds to the sum of the light reflection and the optical loss.

 Fig. 4 is a view showing the optical transmission of the first embodiment of the photonic crystal multi-port circulator of the present invention, wherein the waveguide port 61 is an incident waveguide port, the waveguide port 62 is an exit waveguide port, and the waveguide port 63 to the waveguide port 66 are isolated waveguide ports.

 5 is a schematic diagram of optical transmission of a first embodiment of a photonic crystal multi-port circulator according to the present invention. The waveguide port 64 is an incident waveguide port, the waveguide port 65 is an exit waveguide port, and the waveguide ports 61 to 63 and the waveguide port 66 are isolated waveguide ports. .

 6 is a schematic structural view of a second embodiment of a photonic crystal multi-port circulator according to the present invention, wherein the circulator is a photonic crystal eight-port circulator.

 7 is a schematic structural view of a third embodiment of a photonic crystal multi-port circulator according to the present invention, wherein the circulator is a photonic crystal nine-port circulator.

8 is a schematic structural view of a fourth embodiment of a photonic crystal multi-port circulator according to the present invention, wherein The circulator is a photonic crystal ten port circulator.

 9 is a schematic structural view of a fifth embodiment of a photonic crystal multi-port circulator according to the present invention, wherein the circulator is a photonic crystal twelve-port circulator. detailed description

 The invention will now be further elucidated with reference to the drawings and specific embodiments.

 First Embodiment: Photonic crystal six-port circulator.

 The first is to construct the body of the photonic crystal six-port circulator to determine the structural parameters and constituent materials. As shown in FIG. 1, the circulator body of the present invention is a two-dimensional photonic crystal in which the first air column 10 is periodically distributed in the background of the dielectric material. The first air column 10 has a plane in cross section, and the axis along the z-axis direction, the crystal of the photonic crystal. The lattice constant a is set to Ιμηι. The diameter d of the first air column 10 is 0.72 μm, and the center line of any three adjacent first air columns 10 constitutes an equilateral triangle, that is, the first air column 10 is triangular. Symmetrical arrangement. The dielectric material may be selected from a gallium nitride (GaN) material having a refractive index of 2.5. The calculation method of plane wave expansion shows that the dielectric substrate-air column photonic crystal has a wide TM polarized wave (magnetic field along the z-axis direction) photonic band gap, and the band gap width is from the normalized frequency "/ =0.307 to = 0.418, which represents the wavelength of light.

Figure 2 is a schematic diagram of the structure of the photonic crystal six-port circulator. In the above photonic crystal, six first air columns 10 (nearly spaced five first air columns 10) at exactly the apex of the equilateral hexagon are selected, and their diameters are enlarged to 0.8 μm and filled with magneto-optical material, while Applying a magnetic field parallel to the axis of the first air column 10 (ζ axis), each magneto-optical material column (marked by the grid line) and the surrounding six first air columns 10 constitute a point defect magneto-optical cavity, forming six photons The crystal magneto-optical chambers are labeled as a first magneto-optical chamber 51, a second magneto-optical chamber 52, a third magneto-optical chamber 53, a fourth magneto-optical chamber 54, a fifth magneto-optical chamber 55, and a sixth magneto-optical chamber 56, respectively. The magneto-optical material filling the first air column 10 can be selected as Bismuth Iron Garnet (BIG) with a diagonal element ε. And non-diagonal element ε. Selected as 6.25 and 0.0517. On the periphery of the six magneto-optical cavities arranged in a ring shape, one connecting waveguide is constructed corresponding to each of the magneto-optical cavities, that is, the first waveguide 1, the second waveguide 2, the third waveguide 3, the fourth waveguide 4, the fifth waveguide 5, and the Six waveguides 6. Each waveguide is formed by filling a column of first air columns 10 with a dielectric material of gallium nitride. The intersection of the six waveguides coincides with the center of the regular hexagon formed by the six magneto-optical cavities, and the angle between the intersections of adjacent waveguides Both are 60 degrees. The waveguide ports corresponding to the first waveguide 6 to the sixth waveguide 6 are the first waveguide port 61, the second waveguide port 62, the third waveguide port 63, the fourth waveguide port 64, the fifth waveguide port 65, and the sixth waveguide port 66, respectively. . In addition, in order to improve the optical coupling efficiency, two second air columns 20 having a diameter of 0.36 μm are disposed between adjacent magneto-optical cavities and adjacent magneto-optical cavities and the waveguide.

In order to improve the performance of the circulator, two third-stage air cylinders 30 (in FIG. 1, ie, air cylinders) and fourth air cylinders 40 with increasing diameters are disposed around each magneto-optical chamber. In FIG. 1, that is, the air column, the diameter of the fourth air column 40 is larger than the diameter of the third air column 30, and the diameter of the third air column 30 is larger than the diameter of the first air column 10. The optimal size of the third air column 30 and the fourth air column 40 is determined according to the optical transmission efficiency of the port: The light is set to be incident from the waveguide port 61, and the detection point is respectively set at each waveguide port to obtain a corresponding optical power, wherein the waveguide port 61 Corresponding to the reflected light power, the waveguide port 62 to the waveguide port 66 correspond to the transmitted optical power. By adjusting the diameters of the third air column 30 and the fourth air column 40, an optimum spectrum as shown in FIG. 3 is obtained, wherein the solid line corresponds to the optical power of the waveguide port 62, and the broken line corresponds to the optical power of the waveguide port 63, the dotted line Corresponding to the optical power of the waveguide port 64 or the waveguide port 65, the dashed-dotted line corresponds to the optical power of the waveguide port 66, and the dashed-double dotted line corresponds to the sum of the light reflection and the optical loss. The results show that the optimal normalized frequency of the circulator operation is "/=0.3508, at which time the waveguide port 62 is the optical output waveguide port, and the optical power reaches a maximum of 95%; the waveguide port 63 and the waveguide port 66 are optically isolated ports. The optical power reaches a minimum of 2% and 1%, respectively; the waveguide port 64 and the waveguide port 65 are optically isolated waveguide ports, and the optical power is almost 0; the sum of optical loss and light reflection reaches a minimum of 2%. Corresponding to the normalized frequency "/=0.3508, the optimal diameters of the third air column 30 and the fourth air column 40 are 0.80μηι and 0.88μηι, respectively. Due to the rotational symmetry of the structure, the above optimized parameters are for other waveguides from light. The same applies to port incidence. Furthermore, the finite-difference time-domain method is used to numerically simulate the optical transmission characteristics, and the performance of the photonic crystal six-port loop device is examined.

 The normalized frequency " / = 0.3508 is selected as the circulatory operating frequency, and the corresponding circulator operating wavelength is = (1/0.3508) μηι, ie 2.85μηι. Due to the optical rotation effect of the magneto-optical cavity, the magneto-optical cavity is caused. The wave vector of the magnetic field rotates, and the light transmission effect and the optical isolation effect are respectively generated for the waveguides connected to the magneto-optical cavity, thereby realizing the function of the light unidirectional optical ring between the six waveguides. The following selection of light incident from the waveguide port 61 and the waveguide port 64 respectively illustrates the optical transmission characteristics of the circulator.

 Referring to Fig. 4, light is incident from the waveguide port 61, and finally output from the waveguide port 62, and the waveguide port 63 to the waveguide port 66 are both in an optically isolated state. The optical power of the output waveguide port 62 is 95%; the optical power of the waveguide port 63 to the waveguide port 66 in the isolated state is less than 3%, wherein the optical power of the waveguide port 63 is 2%, and the optical power of the waveguide port 66 is 1. %, the optical power of the waveguide port 64 and the waveguide port 65 is almost zero. The sum of light loss and light reflection reaches a minimum of 2%. For the case where light is incident from the waveguide port 61, the second air column 20 having a reduced diameter disposed between the adjacent magneto-optical cavity and the magneto-optical cavity, the adjacent magneto-optical cavity and the waveguide exhibits a dual function, specifically: The second air column 20 between the magneto-optical cavity 51 and the second magneto-optical cavity 52, the first magneto-optical cavity 51 and the first waveguide 1, the second magneto-optical cavity 52 and the second waveguide 2 exhibits optical coupling; a second magneto-optical chamber 52 and a third magneto-optical chamber 53, a third magneto-optical chamber 53 and a fourth magneto-optical chamber 54, a fourth magneto-optical chamber 54 and a fifth magneto-optical chamber 55, a fifth magneto-optical chamber 55 and a sixth a magneto-optical cavity 56, a sixth magneto-optical cavity 56 and a first magneto-optical cavity 51, a third magneto-optical cavity 53 and a third waveguide 3, a fourth magneto-optical cavity 54 and a fourth waveguide 4, a fifth magneto-optical cavity 55 and The second air column 20 between the fifth waveguide 5, the sixth magneto-optical cavity 56 and the sixth waveguide 6 exhibits optical isolation.

Referring to FIG. 5, light is incident from the waveguide port 64, and finally outputted from the waveguide port 65, and the waveguide port 61 to the waveguide port 63 and the waveguide port 66 are both in an optically isolated state. The optical power of the output waveguide port 65 is 95%; the optical power of the waveguide port 61 to the waveguide port 63 and the waveguide port 66 in the isolated state are all below 3%, wherein the optical power of the waveguide port 66 is 2%, and the waveguide port 63 is Optical power is 1%, The optical power of the waveguide port 61 and the waveguide port 62 is almost zero. The sum of light loss and light reflection reaches a minimum of 2%. For the case where light is incident from the waveguide port 64, the second air column 20 having a reduced diameter disposed between the adjacent magneto-optical cavity and the magneto-optical cavity, the adjacent magneto-optical cavity and the waveguide exhibits a dual function, specifically: The second air column 20 between the magneto-optical cavity 54 and the fifth magneto-optical cavity 55, the fourth magneto-optical cavity 54 and the fourth waveguide 4, the fifth magneto-optical cavity 55 and the fifth waveguide 5 exhibits optical coupling; a magneto-optical cavity 51 and a second magneto-optical cavity 52, a second magneto-optical cavity 52 and a third magneto-optical cavity 53, a third magneto-optical cavity 53 and a fourth magneto-optical cavity 54, a fifth magneto-optical cavity 55 and a sixth a magneto-optical cavity 56, a sixth magneto-optical cavity 56 and a first magneto-optical cavity 51, a first magneto-optical cavity 51 and a first waveguide 1, a second magneto-optical cavity 52 and a second waveguide 2, a third magneto-optical cavity 53 and The second air column 20 between the third waveguide 3, the sixth magneto-optical cavity 56 and the sixth waveguide 6 exhibits optical isolation.

 For the photonic crystal six-port circulator of the present invention, the light incident from the other waveguide ports is specifically as follows: the light input from the waveguide port 62 is output from the waveguide port 63, and the waveguide port 61, the waveguide port 64 to the waveguide port 66 are in an optically isolated state. The light input from the waveguide port 63 is output from the waveguide port 64, the waveguide port 61, the waveguide port 62, the waveguide port 65, and the waveguide port 66 are in an optically isolated state; the light input from the waveguide port 65 is output from the waveguide port 66, and the waveguide port 61 The waveguide port 64 is in an optically isolated state; the light input from the waveguide port 66 is output from the waveguide port 61, and the waveguide port 62 to the waveguide port 65 are in an optically isolated state. The port optical power for the incidence of six different waveguide ports is shown in Table 1 below.

Table 1 shows the sum of optical power, light reflection and loss of each port under different waveguide port incidence conditions.

端口 62→63 1% 95% 2% 0 0 2% 端口 63→64 0 1% 95% 2% 0 2% 端口 64→65 0 0 1% 95% 2% 2% 端口 65→66 2% 0 0 1% 95% 2% 端口 66→61 95% 2% 0 0 1% 2% 针对以上参数的光子晶体环行器， 可以实现高效率和高隔离度的单方向 环行光传输功能。

Port 62→63 1% 95% 2% 0 0 2% Port 63→64 0 1% 95% 2% 0 2% Port 64→65 0 0 1% 95% 2% 2% Port 65→66 2% 0 0 1% 95% 2% Port 66→61 95% 2% 0 0 1% 2% For the photonic crystal circulator with the above parameters, high-efficiency and high-isolation unidirectional circular optical transmission can be realized.

 According to the proportional scaling characteristics of the photonic crystal, that is, the ratio of the photonic crystal lattice constant, the size of the dielectric material, the size of the air column and the magneto-optical material column are equally increased or decreased, and the appropriate material is selected, and the loop function of the structure can be Expand to any electromagnetic wave band. Specifically: a given working wavelength is selected as the lattice constant = «^ / :) = 0.3508 where "and the lattice constant and operating wavelength in the above embodiment, respectively, the size of the medium in the system, the size of the dielectric material, the air column The parameters such as the size of the magneto-optical material column are scaled in the same manner as / times the value described in the above embodiment.

 The selected working wavelength Α = 1.550μηι, the corresponding lattice constant is ^=0.544 111, the diameter of the first air column 10 is 0.392μηι, and the diameter of the magneto-optical material column is 0.435μηι, optimizing the second air column 20, The diameters of the third air column 30 and the fourth air column 40 are 0.196 μm, 0.435 μm, and 0.479 μηι, respectively. When light waves having a wavelength of 1.550 μη are incident from different waveguide ports, the waveguide port 61 to the waveguide port 62 and the waveguide port 62 are still obtained. Optical transmission characteristics to the waveguide port 63, the waveguide port 63 to the waveguide port 64, the waveguide port 64 to the waveguide port 65, the waveguide port 65 to the waveguide port 66, and the waveguide port 66 to the waveguide port 61, the optical power of each port is the same as in Table 1. .

 Second Embodiment: Photonic crystal eight-port circulator.

In the same dielectric substrate-air column type photonic crystal as the six ports of the photonic crystal, the port expansion of the circulator can be realized by cascading the magneto-optical cavities into a plurality of ring structures. In photonic crystals, lattice constants For Ιμηι, the diameter 6 of the first air column 10 is 0.72 μm _{; the} dielectric material may be selected from a gallium nitride (GaN) material having a refractive index of 2.5; the magneto-optical cavity is a magnetic material formed by filling a single first air column 10 with a magneto-optical material. The column of optical material is formed with the surrounding six first air columns 10, and a magnetic field is applied to the column of magneto-optical material in a direction parallel to the axis of the first air column 10 (z-axis). As shown in FIG. 6, ten magneto-optical cavities (first magneto-optical cavity 51 to tenth magneto-optical cavity 510) are cascaded to form two regular hexagonal connected structures, wherein two regular hexagons have a common edge. And corresponding to the first magneto-optical cavity 51, the second magneto-optical cavity 52, the third magneto-optical cavity 53, the sixth magneto-optical cavity 56, the seventh magneto-optical cavity 57, the eighth magneto-optical cavity 58, and the ninth magneto-optical cavity 59 A waveguide is formed outwardly from the tenth magneto-optical cavity 510 to obtain a photonic crystal eight-port circulator.

 Third Embodiment: Photonic crystal nine-port circulator.

 Similarly, as shown in FIG. 7, thirteen magneto-optical cavities (first magneto-optical cavity 51 to thirteenth magneto-optical cavity 513) are cascaded to form three regular hexagonal connected structures, three of which are hexagonal. There are two common sides, and corresponding to the first magneto-optical cavity 51, the second magneto-optical cavity 52, the third magneto-optical cavity 53, the eighth magneto-optical cavity 58, the ninth magneto-optical cavity 59, and the tenth magneto-optical cavity 510 The eleventh magneto-optical cavity 511, the twelfth magneto-optical cavity 512 and the thirteenth magneto-optical cavity 513 each construct a waveguide to obtain a photonic crystal nine-port circulator.

 Fourth Embodiment: Photonic crystal ten port circulator.

 As shown in FIG. 8, sixteen magneto-optical cavities (first magneto-optical cavity 51 to sixteenth magneto-optical cavity 516) are cascaded to form four regular hexagonal connected structures, wherein four regular hexagonal centers are sequentially connected. The lines constitute a parallelogram, and the corresponding magneto-optical cavities 51, 52, 58, 59, 510, 512, 513, 514, 515, and 516 each construct a waveguide outward to obtain a ten-port photonic crystal circulator.

 Fifth Embodiment: Photonic crystal twelve-port circulator.

 As shown in FIG. 9, twenty-four magneto-optical cavities (the first magneto-optical cavity 51 to the twenty-fourth magneto-optical cavity 524) are cascaded to form a structure of seven regular hexagonal connections, wherein six regular hexagons are symmetric. Distributed around a regular hexagon, and corresponding to the magneto-optical chambers 51, 52, 59, 510, 511, 512, 517, 518, 519, 520, 523 and 524, a waveguide is formed outward to obtain a twelve-port photonic crystal. Circulator.

In the above-mentioned port-expanded photonic crystal circulator structure, each magneto-optical cavity is in the positive hexagonal The apex of the shape, and the structural optimization method and parameters are the same as those of the six-port circulator, that is, two second diameters of 0.36μηι are disposed between the adjacent magneto-optical cavity and the magneto-optical cavity, the adjacent magneto-optical cavity and the waveguide. The air column is provided with two third air columns 30 and a fourth air column 40 having a diameter of 0.80 μm and 0.88 μm centered on each of the magneto-optical chambers.

 In the above eight-port photonic crystal circulator, the connecting waveguides of the eight magneto-optical chambers 51, 52, 53, 56, 57, 58, 59 and 510 are the waveguide port 61 to the waveguide port 68, respectively. The optical loop function implemented by the eight-port circulator is that light input from the waveguide port 61 is output from the waveguide port 62, and the waveguide ports 63-68 are in an optical isolation state; light input from the waveguide port 62 is output from the waveguide port 63, and the waveguide port 61 is output. 64-68 is in an optically isolated state; light input from the waveguide port 63 is output from the waveguide port 64, and the waveguide ports 61, 62, 65-68 are in an optically isolated state; light input from the waveguide port 64 is output from the waveguide port 65, and the waveguide Ports 61-63, 66-68 are in an optically isolated state; light input from waveguide port 65 is output from waveguide port 66, waveguide ports 61-64, 67, 68 are in an optically isolated state; light input from waveguide port 66 is from a waveguide port 67 output, the waveguide ports 61-65, 68 are in an optically isolated state; the light input from the waveguide port 67 is output from the waveguide port 68, the waveguide ports 61-66 are in an optically isolated state; the light input from the waveguide port 68 is output from the waveguide port 61 The waveguide ports 62-67 are in an optically isolated state.

 The optical ring functions of the above nine-port, ten-port and twelve-port photonic crystals are shown in Table 2 below.

Table 2 Loop characteristics of eight-port, nine-port, ten-port, twelve-port magneto-optical photonic crystal circulators Circulator type Port loop characteristics Port 61-62, port 62→63, port 63→64, port 64→65, port 65 eight ports

 →66, port 66→67, port 67→68, port 68-61 port 61-62, port 62→63, port 63→64, port 64→65, port 65 nine port

→66, port 66→67, port 67→68, port 68→69, port 69-61 Port 61-62, port 62→63, port 63→64, port 64→65, port 65 ten port→66, port 66→67, port 67→68, port 68→69, port 69-610,

 Port 610-61 port 61-62, port 62→63, port 63→64, port 64→65, port 65 twelve ports→66, port 66→67, port 67→68, port 68→69, port 69— 610,

 Port 610-611, port 611-612, port 612-61

In the above embodiment, after applying a magnetic field parallel to the axis of the first air column (Z-axis), the magneto-optical material can be expressed by the following three-dimensional tensor:

 0

 ε =

^£ y - 0

The diagonal element ε ₀ in the 0 0 tensor corresponds to the dielectric constant of the material when no external magnetic field is applied, and the non-diagonal element ε _α reflects the intensity of the magneto-optical effect after the external magnetic field is applied. The optical rotation effect of the photonic crystal magneto-optical cavity specifically means that the magneto-optical effect generated by the magneto-optical material in the point defect cavity causes the eigenmode supported by the defect cavity to form a mutual coupling effect, so that the electromagnetic field distribution pattern in the cavity undergoes a rotational change. The optical rotation effect of the magneto-optical cavity enables the wave vector of the magnetic field in the cavity to produce parallel and offset effects on the waveguide connected to the magneto-optical cavity respectively. The waveguide parallel to the wave vector corresponds to the optical transmission state, and the waveguide deviated from the wave vector corresponds to the light. Isolated state.

 In the above embodiment, two second air columns 20 having a reduced diameter are disposed between the adjacent magneto-optical chambers and the magneto-optical chambers, and have different effects for different situations: when the waveguides corresponding to the two magneto-optical cavities are in an optical transmission state When the second air column 20 connecting the two magneto-optical cavities contributes to the light transmission; when the waveguides of the two magneto-optical cavities are in an optically isolated state, the second air column 20 connecting the two magneto-optical cavities is helpful In the light isolation effect.

In the above embodiment, two second air columns 20 having a reduced diameter are disposed between the adjacent magneto-optical cavities and the waveguide, and have different effects for different situations: when the magneto-optical cavity and the corresponding waveguide generate light transmission In the state, the connected second air column 20 contributes to light transmission; when the magneto-optical cavity is in an optically isolated state from the corresponding waveguide, the connected second air column 20 contributes to optical isolation.

 In the above embodiment, the third air column 30 and the fourth air column 40 having two periods of increasing diameter are disposed centering on the magneto-optical cavity, on the one hand, they can reduce interference between the waveguides, and on the other hand, they can improve the transmission waveguide. s efficiency.

 In the above embodiment, when the distance between the adjacent magneto-optical cavities is the same, the circulator has a function of the unidirectional optical ring line, and the "lattice constant of the photonic crystal," is a natural number greater than or equal to 5, preferably, "A natural number greater than or equal to 5 and less than or equal to 10.

 In the above embodiment, the length of the waveguide is at least three of the photonic crystal lattice constants, and the length of the waveguide is increased, and the unidirectional optical ring function of the circulator is unchanged.

 In the above embodiment, the refractive index of the medium, the size of the first air column to the fourth air column may be adjusted within an appropriate range.

 In the above embodiment, the first to fourth air columns and the magneto-optical material columns periodically distributed in the dielectric material may have a circular, quadrangular, pentagonal or hexagonal cross section.

 In the above embodiment, the unidirectional direction of the structure is selected by scaling the parameters of the photonic crystal lattice constant, the size of the dielectric material, the size of the first air column to the fourth air column, and the size of the magneto-optical material column. The optical ring function can be extended to any electromagnetic wave band application.

The invention utilizes the annular cascading mode and the optical rotation effect of the magneto-optical cavity to realize the single-direction circular transmission of the optical signals between the six ports, and can provide high-efficiency optical transmission and high optical isolation between the six ports. The invention utilizes a photonic crystal magneto-optical cavity to further cascade into a plurality of annular structures, which can realize expansion of the circulator port; in the above dielectric substrate-air column type photonic crystal, ten, thirteen, ten respectively Six or twenty-four magneto-optical cavities are cascaded to form two, three, four, and seven regular hexagonal connected structures, and a waveguide is formed outward corresponding to the outermost magneto-optical cavity, that is, eight ports are obtained. a nine-port, ten-port, twelve-port photonic crystal circulator; in the second to fifth embodiments, a magneto-optical cavity and a waveguide The composition, structure optimization method and parameters are the same as those of the above photonic crystal six-port circulator. The magneto-optical cavity is cascaded into a plurality of ring-shaped photonic crystal circulators, which can realize single-direction circular transmission of optical signals between more ports. The circulator of the present invention is compact in structure and easy to integrate with other photonic crystal devices. Further, the cascode photonic crystal magneto-optical cavity constitutes a plurality of connected ring structures, and the port of the circulator is expanded to obtain a more versatile circulator.

 The above are only the preferred embodiments of the present invention, and all changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

Claim  A photonic crystal multi-port circulator, wherein the photonic crystal body is composed of a first air column symmetrically distributed in a dielectric material, and is characterized in that: at least six magneto-optical cavities are included, and the center of the magneto-optical cavity is sequentially The wiring forms a regular hexagon or a plurality of cascading regular hexagons, and at least six waveguides are symmetrically constructed in a regular hexagon or a plurality of cascading regular hexagons, each waveguide being filled with a column of dielectric material. An air column is formed, and two second air columns having a diameter smaller than a diameter of the first air column are disposed between adjacent magneto-optical cavities and between the adjacent magneto-optical cavities and the waveguide, centered on each of the magneto-optical cavities A third air column and a fourth air column with two cycles of increasing diameter are disposed around, and light is input from any of the waveguides and outputted from the next adjacent waveguide, and the remaining waveguides are all optically isolated to form a single-directional optical ring transmission.  2. The photonic crystal multi-port circulator according to claim 1, comprising: an eight-port circulator having ten magneto-optical cavities, wherein the centers of the ten magneto-optical cavities are sequentially connected to form two cascades. The regular hexagon forms eight waveguides symmetrically on the periphery of the two cascaded regular hexagons.  3. The photonic crystal multi-port circulator according to claim 1, comprising: a nine-port circulator having thirteen magneto-optical cavities, wherein the centers of the thirteen magneto-optical cavities are sequentially connected to form three A cascading regular hexagon, nine waveguides are symmetrically constructed around the three cascading regular hexagons.  4. The photonic crystal multi-port circulator according to claim 1, comprising: a ten-port circulator having sixteen magneto-optical cavities, wherein the centers of the sixteen magneto-optical cavities are sequentially connected to form four A cascading regular hexagon, ten waveguides are symmetrically constructed around the four cascading regular hexagons.  5. The photonic crystal multi-port circulator according to claim 1, comprising: a twelve-port circulator having twenty-four magneto-optical cavities, wherein the centers of the twenty-four magneto-optical cavities are sequentially connected Seven cascading regular hexagons are formed, and twelve waveguides are symmetrically constructed around the seven cascading regular hexagons. 6. A photonic crystal multi-port circulator according to any one of claims 1 to 5, characterized in that Wherein: each of the magneto-optical cavities comprises a magneto-optical material column and six first air columns distributed around the magneto-optical material column, the magneto-optical material column being filled with a magneto-optical material to a first air column A magnetic field is formed in a direction parallel to the axis of the first air column.  The photonic crystal multi-port circulator according to any one of claims 1 to 5, wherein: each of the magneto-optical chambers is provided with two third-stage air column and fourth air having increasing diameters around the center. The column has a fourth air column having a diameter larger than a diameter of the third air column, and a third air column having a diameter larger than a diameter of the first air column.  The photonic crystal multi-port circulator according to any one of claims 1 to 5, wherein: when the distance between the adjacent magneto-optical cavities is the same, the circulator has a one-way optical ring function unchanged. α is a lattice constant of a photonic crystal, and n is a natural number of 5 or more and 10 or less.  The photonic crystal multi-port circulator according to any one of claims 1 to 5, wherein: the length of the waveguide is at least three of the photonic crystal lattice constants, and the waveguide length is increased, the circulator single The direction of the optical ring function is unchanged.  The photonic crystal multi-port circulator according to claim 6, wherein: the first to fourth air columns and the magneto-optical material column distributed in the dielectric material have a circular or quadrangular cross section. A pentagon or a hexagon, wherein the first to fourth air columns in the photonic crystal are dielectric columns of a low refractive index material.