A topological optical waveguide device capable of achieving frequency splitting and / or beam splitting and applications thereof

Abstract

The application discloses a topological optical waveguide device capable of realizing frequency division and / or beam splitting and an application thereof, comprising a first photonic crystal module (PC1) and a second photonic crystal module (PC2) which are composed of cage cell; the first photonic crystal module (PC1) and the second photonic crystal module (PC2) respectively have topological nontrivial properties and topological trivial properties; two different boundaries are constructed according to the different Wannier center positions of the first photonic crystal module (PC1) and the second photonic crystal module (PC2), and the frequency division and / or beam splitting effect on light is realized through the combination of the two boundaries.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of application of topological photonic crystals, and relates to a topological optical waveguide device capable of realizing frequency division and / or beam splitting and application thereof. BACKGROUND

[0002] The topological boundary state based on the topological photonic crystal is one of the research hotspots in recent years. As an artificial periodic electromagnetic material, the topological photonic crystal has unique photonic band gap, photonic localization and negative refractive index characteristics, and has a topological protection property. The topological photonic crystal boundary state has strong robustness to various defects such as impurities and disorder. In recent years, the superior robustness of the topological boundary state to optical signal transmission has attracted widespread attention and further research. Optical signals can be localized at the interface of two different structures of topological photonic crystals, thereby realizing robust transmission of the boundary state of the optical signals. The optical waveguide designed by using the topological boundary state can effectively utilize the strong robustness of the topological photonic crystal, reduce energy loss due to low scattering, and has a small structure and is easy to integrate, thus having great application prospects.

[0003] The photonic crystal with a cage lattice can realize two different topological properties by changing the position of the dielectric column in the unit cell. The optical waveguide structure is constructed by two photonic crystals with different topological properties to achieve the effect of topologically protected transmission of optical signals. At present, the existing optical waveguide realized by the topological photonic crystal structure can only realize the functions of beam splitting or frequency division. Due to the C3 symmetry of the cage structure photonic crystal, interchanging the positions of the topologically trivial and non-trivial photonic crystals can obtain two different boundary structures, so that an optical waveguide device capable of realizing frequency division and / or beam splitting can be designed. SUMMARY

[0004] The application designs a topological optical waveguide device capable of realizing frequency division and / or beam splitting and application thereof, which has a simple structure. The device suppresses energy scattering and reduces loss by means of the topological protection property, and builds a rhombus combination structure waveguide system by means of two different interface structures, so as to meet more conditions and requirements of the optical communication waveguide device.

[0005] The optical waveguide model disclosed by the application mainly utilizes one-dimensional topological boundary states to construct an optical waveguide, realizes two different working frequency bands of the topological boundary state by interchanging the positions of the topologically trivial and non-trivial photonic crystals, and builds a topological optical waveguide system supporting beam splitting and frequency division by using a rhombus combination structure.

[0006] The technical scheme used in the application is as follows:

[0007] A topological optical waveguide device capable of achieving frequency splitting and / or beam splitting, characterized in that it comprises a first photonic crystal module PC1 composed of a periodic arrangement of first unit cells UC1, and a second photonic crystal module PC2 composed of a periodic arrangement of second unit cells UC2;

[0008] The first unit cells UC1 and the second unit cells UC2 are both cage-shaped unit cells of a regular hexagon shape, with three short axes la and one long axis lb, arranged in a central symmetric manner around the center of the unit cell, and the distance between the centers of two adjacent cage-shaped unit cells is the lattice constant a; the distance between the center of the rhombus-shaped silicon dielectric column in the first unit cell UC1 and the center of the unit cell is d1 = 0.39a, and the distance between the center of the rhombus-shaped silicon dielectric column in the second unit cell UC2 and the center of the unit cell is d2 = 0.19a;

[0009] The first photonic crystal module PC1 has a topologically nontrivial property, and the second photonic crystal module PC2 has a topologically trivial property;

[0010] At least one first photonic crystal module PC1 and at least one second photonic crystal module PC2 are spliced to form at least one boundary 1 and at least one boundary 2, and the boundary 1 and the boundary 2 have an intersection point therebetween;

[0011] The Wannier centers of the first photonic crystal module PC1 located on one side of the boundary 1 are staggered with the Wannier centers of the second photonic crystal module PC2 located on the other side of the boundary 1;

[0012] The Wannier centers of the first photonic crystal module PC1 located on one side of the boundary 2 are arranged in the same array with the Wannier centers of the second photonic crystal module PC2 located on the other side of the boundary 2.

[0013] Further, the number of the first photonic crystal module PC1 and the second photonic crystal module PC2 is two, and the splicing forms two boundary 1 and two boundary 2, and the two boundary 1 and the two boundary 2 intersect at the intersection point O.

[0014] Further, the first photonic crystal module PC1 and the second photonic crystal module PC2 are alternately distributed around the intersection point O.

[0015] Further, the two first photonic crystal modules PC1 are short-axis 16a and long-axis 32a rhombus modules composed of the arrangement of the first unit cells UC1, and the two first photonic crystal modules PC1 are respectively located on the left and right sides of the intersection point O. The second photonic crystal module PC2 is short-axis 16a and long-axis 32a rhombus modules composed of the arrangement of the second unit cells UC62. The rhombus-shaped modules are the second photonic crystal modules PC2 located on the upper and lower sides of the intersection O and mirror-symmetric to each other.

[0016] Further, the lattice constants of the first unit cell UC1 and the second unit cell UC2 are both a=0.5 μm, the cross sections of the unit cells are both regular hexagons, the axes of the three rhombus-shaped silicon dielectric columns are respectively located at the three vertices of the equilateral triangle, and the center of the equilateral triangle is coincident with the center of the unit cell.

[0017] Further, the three dielectric columns of the first unit cell UC1 and the second unit cell UC2 are all the same dielectric column.

[0018] Further, the dielectric column is a rhombus-shaped silicon dielectric column, the short axis of which is l a =0.2a, and the long axis of which is l b =0.346a.

[0019] Further, the frequency range of the topological boundary state that can be realized at the boundary 1 formed by the first photonic crystal module PC1 and the second photonic crystal module PC2 is 0.324(2πc / a)-0.363(2πc / a), but the frequency of 0.324(2πc / a)-0.330(2πc / a) is not in the photonic band gap, so the topological boundary state can be used for the light with the frequency range of 0.330(2πc / a)-0.363(2πc / a) to be transmitted along the boundary 1, wherein c is the speed of light in vacuum.

[0020] Further, the frequency range of the topological boundary state that can be realized at the boundary 2 formed by the first photonic crystal module PC1 and the second photonic crystal module PC2 is 0.352(2πc / a)-0.388(2πc / a); the light with the frequency range of 0.352(2πc / a)-0.388(2πc / a) can be transmitted along the boundary 2, wherein c is the speed of light in vacuum.

[0021] The topological optical waveguide device can be used for simultaneously frequency dividing and / or beam splitting of light.

[0022] The topological optical waveguide device capable of realizing frequency division and / or beam splitting is composed of two photonic crystal structures with different topological properties. The photonic crystal with the expanded state of cage motif cell, i.e. the distance between the center of the first cell and the center of the rhombic silicon dielectric column is d1=0.39a, exhibits topologically nontrivial properties and has a topologically nontrivial photonic band gap; the photonic crystal with the contracted state of cage motif cell, i.e. the distance between the center of the second cell and the center of the rhombic silicon dielectric column is d2=0.19a, exhibits topologically trivial properties and has a topologically trivial photonic band gap. There is a topological phase transition between the two photonic crystal structures. At the one-dimensional interface of the two-dimensional photonic crystals with different topological properties, the optical signal can be efficiently transmitted in a specific frequency range and has strong robustness to structural defects.

[0023] In the present application, only the optical signal in the frequency range of 0.330(2πc / a)-0.363(2πc / a) can be transmitted at the boundary 1 constructed by PC1 and PC2, and only the optical signal in the frequency range of 0.352(2πc / a)-0.388(2πc / a) can be transmitted at the boundary 2. By placing the light source needing beam splitting at the intersection point of any one of UC1 and UC2 in the boundary 1 or the boundary 2, the beam splitting of the light source can be realized. When frequency division is needed, only the intersecting boundary 1 and boundary 2 need to be constructed to realize the frequency division of light.

[0024] Due to the different structures of the boundary 1 and the boundary 2, the frequency ranges supported by the corresponding boundary state waveguides for transmitting optical signals are different, but they have a range of overlapping frequencies. The topological optical waveguide device described in the present application has four boundaries, two of which are the same boundary 1 and two of which are the same boundary 2. In the frequency range where the boundary 1 and the boundary 2 overlap, the optical signal can be transmitted along the four boundaries, realizing four-channel beam splitting; in the frequency range of the boundary 1 (the boundary 2) excluding the overlapping frequency, the optical signal is only transmitted along the boundary 1 (the boundary 2), realizing double-channel beam splitting; compared with the case where the optical signal is only transmitted along the boundary 1 or the boundary 2 (excluding the overlapping frequency), because the corresponding boundary state waveguides support different frequencies for transmitting optical signals, the optical waveguide device also has the function of frequency division.

[0025] The present application is based on the above-mentioned concept of designing a new type of topological photonic crystal structure, a rhombic silicon dielectric column type photonic crystal in an air background, which is relatively simple in structure and only changes the distance between the center of the unit cell and the center of the rhombic silicon dielectric column, thereby obtaining two types of photonic crystals with different topological properties. The combined structure can realize one-dimensional topological boundary state, so that the optical signal can be efficiently transmitted along the one-dimensional interface in the combined structure in a specific frequency range, and has strong robustness to structural defects. The structure is simple to design and easy to prepare, has a small volume and does not produce waste materials in the preparation process, has the advantages of low manufacturing cost and integration. And the optical waveguide supporting one-dimensional topological boundary state can simultaneously realize the functions of frequency division and / or beam splitting in one structure, which has great application prospect in modern integrated optical communication devices. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the arrangement of the cage lattice group. a is the lattice constant, la is the short axis of the rhombic silicon dielectric column, lb is the long axis of the rhombic silicon dielectric column, ε r is the dielectric constant of the dielectric column, and ε0 is the dielectric constant of the air background.

[0027] Figure 2 is the primitive cell of the cage lattice and the corresponding electric field distribution.

[0028] The left graph of (a) is a structural schematic diagram of the first unit cell UC1, and the distance between the center of the rhombic silicon dielectric column and the center of the unit cell is d1=0.39a. The middle and right graphs respectively represent the electric field distribution of the first and second energy bands at the K point in the first Brillouin zone.

[0029] The left graph of (b) is a structural schematic diagram of the second unit cell UC2, and the distance between the center of the rhombic silicon dielectric column and the center of the unit cell is d2=0.19a. The middle and right graphs respectively represent the electric field distribution of the first and second energy bands at the K point in the first Brillouin zone.

[0030] Figure 3 is the energy band structure diagram of the first unit cell UC1, and the lower right corner of the diagram is a schematic diagram of the first Brillouin zone.

[0031] Figure 4 is the energy band structure diagram of the second unit cell UC2.

[0032] Figure 5 is a structural schematic diagram of the boundary 1. On both sides of the boundary 1, the staggered Wannier centers of PC1 and PC2 are separated.

[0033] Figure 6(a) is a schematic diagram of the first supercell SC1, the boundary between the first photonic crystal module PC1 and the second photonic crystal module PC2, and its electric field distribution. The solid box on the far left is an enlarged view of boundary 1. The frequency corresponding to the electric field distribution is 0.363 (2πc / a), where c is the speed of light in vacuum.

[0034] (b) is a schematic diagram of the dispersion curve corresponding to the first supercell SC1. In the dispersion curve diagram, the band gap ranges from 0.330(2πc / a) to 0.410(2πc / a). One curve in the band gap represents the boundary state, with a frequency range of 0.324(2πc / a) to 0.363(2πc / a). However, the boundary state in the range of 0.324(2πc / a) to 0.330(2πc / a) falls into the bulk state range and is not within the band gap range. Therefore, there is no robust energy transfer in the range of 0.324(2πc / a) to 0.330(2πc / a), where c is the speed of light in vacuum.

[0035] Figure 7 This is a schematic diagram of the structure of boundary 2. On both sides of boundary 2, the Wannier center of PC1 corresponds one-to-one with the Wannier center of PC2, and they are arranged in the same array.

[0036] Figure 8 (a) is a schematic diagram of the second supercell SC2, which is the boundary between the first photonic crystal module PC1 and the second photonic crystal module PC2, and its electric field distribution. The dashed box on the far left is an enlarged view of boundary 2. The frequency corresponding to the electric field distribution is 0.352 (2πc / a), where c is the speed of light in vacuum.

[0037] (b) is a schematic diagram of the dispersion curve corresponding to the second supercell SC2. In the dispersion curve diagram, the band gap ranges from 0.326(2πc / a) to 0.420(2πc / a). One curve in the band gap represents the boundary state, with a frequency range of 0.352(2πc / a) to 0.388(2πc / a), where c is the speed of light in vacuum.

[0038] Figure 9 This is a topological optical communication device with a rhombic combined structure composed of PC1 and PC2, capable of simultaneously achieving frequency division and beam splitting. The first photonic crystal module PC1 consists of a first unit cell with a short axis of 16a and a long axis of... The second photonic crystal module PC2 is composed of two rhomboid modules on the left and right sides; the second unit cell has a short axis of 16a and a long axis of 16a. The system consists of two rhomboid modules, which are mirror images of each other. The first photonic crystal module PC1 and the second photonic crystal module PC2 have four intersecting interfaces, with the two upper interfaces being boundary 1 and the two lower interfaces being boundary 2.

[0039] Figure 10 Is with Figure 9 The electric field distribution diagrams of the topological optical communication device that can simultaneously achieve frequency division and beam splitting in different frequency ranges are shown in the figure. Among them, (a) is the electric field distribution diagram of the rhomboid combination structure when the frequency is 0.330(2πc / a)-0.352(2πc / a) (excluding 0.352).

[0040] (b) is the electric field distribution diagram of the rhomboid combination structure at frequencies of 0.363(2πc / a)-0.388(2πc / a) (excluding 0.363);

[0041] (c) is the electric field distribution diagram of the rhomboid combination structure at frequencies of 0.352(2πc / a)-0.363(2πc / a).

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. First photonic crystal module PC1; 1-1. First unit cell UC1; 1-2. Wannier center of first photonic crystal module PC1; 2. Second photonic crystal module PC2; 2-1. Second unit cell UC2; 2-2. Wannier center of second photonic crystal module PC2; 3-1. Boundary 1; 3-2. Boundary 2. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0045] Figure 1 The diagram shows a kakeme lattice and its arrangement. The unit cell of the kakeme lattice consists of three minor axes of l in an air background. a The major axis is l b A hexagonal unit cell is formed by arranging rhombic dielectric pillars in a centrosymmetric manner around the center of the unit cell. Multiple kagome unit cells are periodically arranged to form a kagome lattice. The lattice constant α of the kagome lattice is the distance between the centers of two adjacent kagome unit cells. In the kagome lattice used in this invention, all dielectric pillars are silicon dielectric pillars, and the minor axis of each silicon dielectric pillar is l. a =0.2a, major axis is l b =0.346a.

[0046] The topological optical communication device of the present invention, which can simultaneously realize frequency division and beam division, includes a first photonic crystal module PC1 formed by periodically arranging first unit cells UC1 and a second photonic crystal module PC2 formed by periodically arranging second unit cells UC2.

[0047] like Figure 2As shown, the first unit cell UC1 is formed by expanding the dielectric column in the cage unit cell, and the distance between the center of the unit cell and the center of the rhombic silicon dielectric column is d1=0.39a; the first photonic crystal module PC1 is arranged according to the cage lattice structure. The second unit cell UC2 is formed by expanding the dielectric column in the cage unit cell, and in the second unit cell UC2, the distance between the center of the unit cell and the center of the rhombic silicon dielectric column is d2=0.19a; the second photonic crystal module PC2 is arranged according to the cage lattice structure.

[0048] The lattice constant of the first unit cell and the second unit cell is a=0.5μm, and the three dielectric columns in the unit cell are the same dielectric column, which is a rhombic dielectric column made of silicon material, and the short axis of the dielectric column is l a =0.2a, and the long axis is l b =0.346a.

[0049] The photonic crystal formed by periodically arranging the first unit cell UC1 has a topologically nontrivial property, as shown in Figure 3 The photonic crystal formed by periodically arranging the second unit cell UC2 has a topologically trivial property, as shown in Figure 4 There is a topological phase transition between the two photonic crystals with different topological properties, and in the combined structure composed of the two photonic crystals, light can be robustly transmitted along the interface of the two photonic crystals.

[0050] Specifically, the electromagnetic wave studied in the present application is a TM mode, the value of the lattice constant a is 0.5μm, representing the distance between the centers of two adjacent unit cells; the short axis of the rhombic silicon dielectric column is l a =0.2a, and the long axis is l b =0.346a. The dielectric constant of the silicon material is ε r =11.7, and the dielectric constant of the air background is ε0=1. The frequency of the topologically trivial and topologically nontrivial photonic band gap is approximately the same: 0.330(2πc / a)-0.405(2πc / a), where c is the speed of light in vacuum. In this frequency range, the photons are localized, the scattering of the photons is suppressed, and the optical signal cannot propagate in the structure.

[0051] In order to verify the one-dimensional boundary state between the first photonic crystal module PC1 and the second photonic crystal module PC2, the first photonic crystal module PC1 and the second photonic crystal module PC2 are designed to have a unit cell boundary as a contact interface, and a crystal structure with a boundary 1 is constructed by splicing, as shown in Figure 5As shown, the Wannier center of the first photonic crystal module PC1, located on one side of boundary 1, is offset from the Wannier center of the second photonic crystal module PC2, located on the other side of boundary 1. Taking one supercell of this crystal structure as an example, namely the first supercell SC1, as shown... Figure 6 As shown in (a), the periodic wave vector k was processed using the software COMSOL. x Perform a scan, solve for the eigenvalues, calculate the frequency of the wave, and obtain... Figure 6 In the dispersion curve in (b), there is a boundary state within the photonic bandgap with a frequency range of 0.324(2πc / a)-0.363(2πc / a). However, the range of 0.324(2πc / a)-0.330(2πc / a) is not within the photonic bandgap, so there will be no energy transmission within the frequency range of 0.324(2πc / a)-0.330(2πc / a). Only the optical signal within the frequency range of 0.330(2πc / a)-0.363(2πc / a) can be transmitted along the boundary 1 of the PC1 and PC2 structures, where c is the speed of light in vacuum.

[0052] Similarly, to verify the effect of combining two photonic crystals with different topological properties on the boundary states, a first photonic crystal module PC1 and a second photonic crystal module PC2 were designed and spliced ​​together with the unit cell boundary as the contact interface to construct a crystal structure with boundary 2, as shown below. Figure 7 As shown. The Wannier centers of the first photonic crystal module PC1 located on one side of boundary 2 are arranged in the same array as the Wannier centers of the second photonic crystal module PC2 located on the other side of boundary 2. Taking one supercell of this crystal structure as an example, namely the second supercell SC2, as shown... Figure 8 As shown in (a), the periodic wave vector k was processed using the software COMSOL. x Perform a scan, solve for the eigenvalues, calculate the frequency of the wave, and obtain... Figure 8 In the dispersion curve in (b), there exists a boundary state within the photonic bandgap with a frequency range of 0.352(2πc / a)-0.388(2πc / a), where c is the speed of light in vacuum. Therefore, only optical signals within the frequency range of 0.352(2πc / a)-0.388(2πc / a) can propagate along the boundary 2 of the PC1 and PC2 structures.

[0053] The boundary 1 constructed by PC1 and PC2 can only transmit optical signals in the frequency range of 0.330(2πc / a)-0.363(2πc / a), and the boundary 2 can only transmit optical signals in the frequency range of 0.352(2πc / a)-0.388(2πc / a). By placing the light source to be split at any intersection of UC1 and UC2 in either boundary 1 or boundary 2, the beam splitting of the light source can be achieved.

[0054] When frequency division is required, it is only necessary to construct intersecting boundary 1 and boundary 2 to achieve frequency division of light.

[0055] To achieve frequency division and beam splitting of light, a device such as... was designed. Figure 9 The rhomboid combination structure shown, consisting of PC1 and PC2, is only one specific embodiment. The first photonic crystal module PC1 is formed by arranging first unit cells UC1, with a minor axis of 16a and a major axis of... The module is diamond-shaped, with two first photonic crystal modules PC1 located on the left and right sides of the intersection point O. The second photonic crystal module PC2 is composed of second unit cells UC2 arranged in a shape with a minor axis of 16a and a major axis of... The system consists of a rhomboid module, with two second photonic crystal modules (PC2) located above and below the intersection point O, respectively, and mirror-symmetric to each other. The two first photonic crystal modules (PC1) and the two second photonic crystal modules (PC2) have four pairwise intersecting interfaces. The two upper interfaces have identical structures, both designated as boundary 1, marked with solid lines; the solid-lined boxes represent magnified views of the surrounding structure of this type of interface. The two lower interfaces have identical structures, both designated as boundary 2, marked with dashed lines; the dashed-lined boxes represent magnified views of the surrounding structure of this type of interface. The ports of the four interfaces are marked with dots and numbered sequentially as 1, 2, 3, and 4. A point source marked with a pentagram is placed at the center of the rhomboid composite structure, i.e., at intersection point O, to excite the boundary states.

[0056] The electric field distribution corresponding to the designed rhombic composite structure is as follows: Figure 10As shown, (a) is the electric field distribution diagram of the rhombus combined structure when the frequency is 0.330(2πc / a)-0.352(2πc / a) (excluding 0.352(2πc / a)), the optical signal is only transmitted along the upper two boundary state channels, and the double-channel beam splitting effect is achieved; (b) is the electric field distribution diagram of the rhombus combined structure when the frequency is 0.363(2πc / a)-0.388(2πc / a) (excluding 0.363(2πc / a)), the optical signal is only transmitted along the lower two boundary state channels, and the double-channel beam splitting effect is achieved; (c) is the electric field distribution diagram of the rhombus combined structure when the frequency is 0.352(2πc / a)-0.363(2πc / a), the optical signal can be transmitted along the upper and lower four boundary state channels, and the four-channel beam splitting effect is achieved. Wherein, c is the speed of light in vacuum. As can be seen by comparing (a) and (b), the rhombus combined structure also has the effect of frequency division on the optical signal, when the frequency of the optical signal is 0.330(2πc / a)-0.352(2πc / a) (excluding 0.352(2πc / a)), only in the upper two topological boundary state channels, the optical signal is output from the port 1 and the port 2; when the frequency of the optical signal is 0.363(2πc / a)-0.388(2πc / a) (excluding 0.363(2πc / a)), only in the lower two topological boundary state channels, the optical signal is output from the port 3 and the port 4.

[0057] All the embodiments described above are preferred embodiments of the present application, but the present application is not limited to the above embodiments. Any obvious improvement, replacement or modification made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application. Any structure directly derived from the disclosure of the present application shall fall within the protection scope of the present application.

Claims

1. A topological optical waveguide device capable of frequency division and / or beam splitting, characterized in that, It includes a first photonic crystal module PC1 composed of a periodic arrangement of first unit cells UC1, and a second photonic crystal module PC2 composed of a periodic arrangement of second unit cells UC2. The first unit cell UC1 and the second unit cell UC2 are both in an air background with three short axes. Major axis is A hexagonal kagome cell is formed by arranging rhombic dielectric pillars in a centrally symmetrical manner around the center of the cell. The distance between the centers of two adjacent kagome cells is the lattice constant a. The distance between the center of the rhombic silicon dielectric pillar in the first cell UC1 and the center of the cell is d1 = 0.39a, and the distance between the center of the rhombic silicon dielectric pillar in the second cell UC2 and the center of the cell is d2 = 0.19a. The first photonic crystal module PC1 has topological nontriviality, and the second photonic crystal module PC2 has topological triviality. At least one first photonic crystal module PC1 and at least one second photonic crystal module PC2 are spliced ​​together to form a structure having at least one boundary 1 and at least one boundary 2; The Wannier center of the first photonic crystal module PC1 located on one side of the boundary 1 is staggered with the Wannier center of the second photonic crystal module PC2 located on the other side of the boundary 1; The Wannier center of the first photonic crystal module PC1 located on one side of the boundary 2 is arranged in the same array as the Wannier center of the second photonic crystal module PC2 located on the other side of the boundary 2.

2. The topological optical waveguide device according to claim 1, characterized in that, The first photonic crystal module PC1 and the second photonic crystal module PC2 are both two in number, and are spliced ​​together to form two boundaries 1 and two boundaries 2. The two boundaries 1 and two boundaries 2 intersect at the intersection point O.

3. The topological optical waveguide device according to claim 2, characterized in that, The first photonic crystal module PC1 and the second photonic crystal module PC2 are alternately distributed around the intersection point O.

4. The topological optical waveguide device according to claim 3, characterized in that, The two first photonic crystal modules PC1 are arranged in a first unit cell UC1 with the short axis as follows: Major axis is The rhomboid module consists of two first photonic crystal modules, PC1, located on either side of the intersection point O; the second photonic crystal module, PC2, is composed of second unit cells UC62 arranged with a short axis of... Major axis is The rhomboid module has two second photonic crystal modules, PC2, located on the upper and lower sides of the intersection point O, respectively, and are mirror images of each other.

5. The topological optical waveguide device according to any one of claims 1-4, characterized in that, The lattice constants of the first unit cell UC1 and the second unit cell UC2 are both The cross-section of each unit cell is a regular hexagon, and the axes of the three rhombic silicon dielectric pillars are located at the three vertices of an equilateral triangle, with the center of the equilateral triangle coinciding with the center of the unit cell.

6. The topological optical waveguide device according to any one of claims 1-4, characterized in that, The three dielectric pillars of the first unit cell UC1 and the second unit cell UC2 are all the same dielectric pillars.

7. The topological optical waveguide device according to claim 6, characterized in that, The dielectric pillar is a rhombic silicon dielectric pillar with a minor axis of . The major axis is .

8. The topological optical waveguide device according to claim 7, characterized in that, The frequency range at the boundary 1 formed by the first photonic crystal module PC1 and the second photonic crystal module PC2 that can realize the topological boundary state is 0.324 ( ). -0.363 ), but because of 0.324 ( -0.330 The frequency of ) is not within the photonic bandgap, so this topological boundary state can provide frequencies in the range of 0.330 ( -0.363 The light propagates along the boundary at point 1, where c is the speed of light in a vacuum.

9. The topological optical waveguide device according to claim 7, characterized in that, The boundary 2 formed by the first photonic crystal module PC1 and the second photonic crystal module PC2 can realize topological boundary states in a frequency range of 0.352 ( ). -0.388 It can supply frequencies ranging from 0.352 Hz. -0.388 The light propagates along boundary 2, where c is the speed of light in a vacuum.

10. The topological waveguide device according to any one of claims 1-9 is used for frequency division and / or beam splitting of a light source.

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