A quantum hall effect based topological photonic crystal large width waveguide beam splitter

Abstract

The application provides a quantum Hall effect-based topological photonic crystal wide-width waveguide beam splitter, which comprises a trivial topological region, a trivial topological region containing Dirac cone degeneracy and a non-trivial topological region, the trivial topological region containing Dirac cone degeneracy is arranged between the trivial topological region and the non-trivial topological region, the trivial topological region is uniformly arranged with trivial topological photonic crystals, the trivial topological region containing Dirac cone degeneracy is uniformly arranged with trivial topological photonic crystals containing Dirac cone degeneracy, and the non-trivial topological region is uniformly arranged with non-trivial topological photonic crystals; and a chiral polarization source is arranged in the trivial topological region containing Dirac cone degeneracy. The application uses three topological photonic crystals with different first Brillouin zone photonic band distributions to construct a sandwich structure, realizes one-way, uniform distribution and wide-width waveguide, and further designs the topological photonic crystal wide-width waveguide beam splitter. The application has the transmission characteristics of large capacity, robustness and high efficiency.

Description

Technical Field

[0001] This invention relates to the technical fields of topological photonics, waveguide optics and integrated photonic devices, integrated optical path design, etc., and in particular to a wide-width waveguide beam splitter based on the quantum Hall effect topological photonic crystal. Background Technology

[0002] In recent years, with the rapid development of photonic topological insulators, the field of integrated optics has seen unprecedented progress. Highly integrated micro / nano chips have also gradually appeared in the public eye. Currently, research and exploration in topological photonics mainly focus on several directions, including basic research, applied research, and topological quantum nonlinear effects. Basic research primarily includes unidirectional boundary states of the quantum integer Hall effect based on magneto-optical effects, unidirectional spiral boundary states of the quantum spin Hall effect protected by time-reversal symmetry, unidirectional twisted boundary states of the quantum valley Hall effect based on spatial inversion symmetry breaking, second-order (higher-order) topological insulator angular states, Floquet topological insulators, and topological BIC (continuously bound states). Applied research mainly includes topological nonlinear frequency transformation (second harmonic generation, third harmonic generation, four-wave mixing), and reconfigurable and coded topological insulators. Research on topological quantum nonlinear effects is mainly based on the fact that the environment for generating quantum entanglement is too demanding, while topological protection can reduce the environmental requirements for quantum entanglement. Currently, research on topological quantum nonlinear effects is still in the exploration and verification stage. Therefore, the generation of quantum entangled two-photon states and the construction of experimental platforms are subject to certain limitations.

[0003] In short, fundamental research in topological photonics remains the core of research on topological insulators, especially topologically ordered states based on the Hall effect. Because various topologically ordered states have been proposed and verified, and can be effectively applied to micro / nano-integrated optoelectronic devices, enabling efficient manipulation and application of multiple degrees of freedom of light by electromagnetic artificial microstructures, the study of photonic Hall states has become an irreversible trend in the fields of integrated optics and quantum communication.

[0004] Currently, waveguide photonic devices based on topologically ordered states are developing towards miniaturization, intelligence, multifunctionality, and integration. As a result, a large number of waveguides and photonic devices with transmission characteristics are being developed and designed by researchers.

[0005] In 2020, Professor Liu Zhengyou's research group at Wuhan University proposed a topological heterostructure based on valley phonon crystals, capable of realizing unidirectional, wide-area phonon waves, with the wave width infinitely amplified by the intermediate layer of the heterostructure (Valley-locked waveguide transport in acoustic heterostructures). This work, published in *Nature Communications*, primarily contributes to demonstrating that such a heterostructure can realize infinitely large acoustic wave widths, and that the acoustic field energy can be controlled by changing the width of the intermediate layer. Subsequently, in 2021, Professor Liu's group extended their research from the phonon field to the photonics field, constructing a topological heterostructure using magneto-optical photonic crystals and experimentally demonstrating a wide-area optical waveguide whose width can infinitely expand with the width of the intermediate layer (Topological One-Way Large-Area Waveguide States in Magnetic Photonic Crystals). This work was published in *Physical Review Letters*. This work shows that changing the width of the intermediate layer can achieve control of the optical field intensity, which can be used for optical collimation and focusing. In the same year, Professor Yang Yihao's research group at Zhejiang University proposed that a large-width waveguide could also be realized using a topological heterostructure constructed based on topological valley photons, with the waveguide width modulated by the width of the intermediate layer (Photonic Topological Valley-Locked Waveguides). This work was published in ACS Photonics. This work shows that the waveguide width can be used as a degree of freedom for adjusting the optical field, in addition to frequency, amplitude, and phase. The ordered states of topological photons based on the quantum Hall effect include not only the quantum integer Hall waveguide states and valley quantum Hall twisted states mentioned above, but also the helical boundary states of the quantum spin Hall effect. Currently, the proposal and verification of large-width waveguides in quantum spin Hall effect systems are still in the gaps.

[0006] Based on the above research, this invention designs a unidirectional transmission waveguide based on the quantum Hall effect and a wide-width waveguide beam splitter based on such a waveguide. Summary of the Invention

[0007] Traditional topological boundary states exist at the boundaries of different topological structures, and electromagnetic wave unidirectional boundary states are concentrated at the boundaries or interfaces, decaying rapidly away from the interface. Furthermore, the manipulation of unidirectional boundary states is limited, mainly involving the degrees of freedom of the excitation source such as polarization, frequency, and phase to control the optical field. This invention proposes a large-width unidirectional transmission waveguide based on the quantum Hall effect in a topological photonic crystal, using waveguide width as another way to control the optical field. Based on this, a large-width waveguide beamsplitter is designed. Compared to traditional waveguide beamsplitters, this invention has transmission characteristics such as large capacity, robustness, and high efficiency, making it a novel and multifunctional waveguide beamsplitter.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: a wide-width waveguide beam splitter based on quantum Hall effect topological photonic crystals, comprising a trivial topological region, a trivial topological region with Dirac cone degeneracy, and a non-trivial topological region. The trivial topological region with Dirac cone degeneracy is disposed between the trivial topological region and the non-trivial topological region. Trivial topological photonic crystals are uniformly arranged within the trivial topological region. Trivial topological photonic crystals with Dirac cone degeneracy are uniformly arranged within the trivial topological region with Dirac cone degeneracy. Non-trivial topological photonic crystals are uniformly arranged within the non-trivial topological region. A chiral polarization source is provided within the trivial topological region with Dirac cone degeneracy.

[0009] Preferably, the trite topological region containing Dirac cone degeneracy is divided into two branches on the rear side of the chiral polarization source. The two branches extend downwards or downwards and then output horizontally. A trite topological region and a non-trite topological region are provided between the two branches.

[0010] Preferably, the trite topological region containing Dirac cone degeneracy is shaped like a harpoon; the upper side of the trite topological region containing Dirac cone degeneracy is a non-trivial topological region, and the lower side is a trite topological region.

[0011] Preferably, the trivial topological photonic crystal, the Dirac cone-degenerate trivial topological photonic crystal, and the non-trivial topological photonic crystal are all composed of an alumina cylinder made of an all-electron dielectric material with a dielectric constant of 7.5, an air background, and a cylinder radius of 0.12a; where a is a lattice constant and is taken as 500 nm.

[0012] Preferably, the trivial topological photonic crystal, the Dirac cone-degenerate trivial topological photonic crystal, and the non-trivial topological photonic crystal are all composed of a honeycomb lattice, which contains 6 cylinders arranged in regular hexagons. Changing the distance between the next adjacent cylinders achieves the separation of pseudospin photonic band gaps and mode inversion.

[0013] Preferably, in the trivial topological photonic crystal, the distance from one set of adjacent cylinders to the lattice center is R1 = a / 3, and the distance from another set of adjacent cylinders to the lattice center is R2 = a / 3.5; in the lattice unit of the trivial topological photonic crystal containing Dirac cone degeneracy, R1 = a / 3 and R2 = a / 3; in the lattice unit of the non-trivial topological photonic crystal, R1 = a / 3 and R2 = a / 2.65.

[0014] Preferably, in the first Brillouin zone photonic bandgap distribution of the dirac cone-degenerate trivial topological photonic crystal, the photonic pseudospin states p and d are degenerate at the Γ point, resulting in a double dirac cone. The wide-width waveguide states mainly appear in the dirac cone-degenerate trivial topological region composed of 5 layers of dirac cone-degenerate trivial topological photonic crystals. In the supercell of the sandwich structure containing the trivial topological region, the dirac cone-degenerate trivial topological region, and the non-trivial topological region, the electric field amplitude is uniformly distributed in the dirac cone-degenerate trivial topological photonic crystal region, and the electromagnetic waves are uniformly distributed and concentrated in the dirac cone-degenerate trivial topological region. The waveguide energy is uniformly distributed in the dirac cone-degenerate trivial topological region and the waveguide width is equal to the number of lattice layers in the intermediate layer.

[0015] Preferably, the electric field energy is mainly uniformly distributed in the trivial topological region containing Dirac cone degeneracy. When passing through two 60° angle defects, the electromagnetic wave can still bypass the obstacle and transmit steadily in one direction. The waveguide distribution of the two branches in the beam splitting channel is consistent and the waveguide width is 5a. Even if the waveguide transmission distance is 23a, the electric field energy of the beam splitting channel is about half of the electric field energy of the main channel where the chiral polarization source is located.

[0016] Preferably, the chiral polarization source includes four antennas perpendicular to the z-axis, and a linear polarization source is added to the antennas. The phases of adjacent linear polarization sources are distributed in increments or decreases of π / 2.

[0017] Preferably, the chiral polarization source is chiral circularly polarized, and the antennas are arranged in a square with a side length of 0.2a, where a is a lattice constant.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention constructs a topological heterogeneous structure using all-dielectric topological photonic crystals. The photonic bandgap distributions of the three-layer topological photonic crystal structure are different, namely, topological trivial photonic bandgap, double degenerate trivial photonic bandgap, and topological nontrivial photonic bandgap. The first Brillouin zone photonic band distributions of the three topological photonic crystals are different. Using these three photonic crystals to construct a sandwich structure, a wide-width waveguide is obtained. Based on the principle of bulk-edge correspondence in topological insulators, a topological heterogeneous structure is constructed using three different topological photonic crystals. A bulk-edge state appears in the middle topological layer, realizing a unidirectional, uniformly distributed, and wide-width waveguide. Subsequently, based on the transmission characteristics of the wide-width waveguide, a topological photonic crystal wide-width waveguide beamsplitter is further designed. This invention can be used for the research and development and application of novel multifunctional photonic devices and integrated optical circuits. This invention has transmission characteristics such as high capacity, robustness, and high efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 The figures show the bulk-edge band and energy distribution of the wide-width waveguide in the topological photonic crystal heterojunction of this invention. (a) is a schematic diagram of the topological photonic crystal heterojunction structure, (b) is the bulk-edge photonic band distribution of the topological photonic crystal heterojunction structure, (c) is the electric field energy distribution of the wide-width waveguide in the topological heterojunction, and (d) is the normalized electric field amplitude distribution along the y-axis of the wide-width waveguide in the topological heterojunction.

[0022] Figure 3 The following is a simulation example diagram of the present invention, wherein (a) is the electric field energy distribution of the topological wide-width waveguide beam splitter, (b) is the Poynting vector distribution of the topological wide-width waveguide beam splitter, and (c) is the normalized electric field amplitude distribution of the topological wide-width waveguide beam splitter along the y-axis.

[0023] In the figure, 1 is a trivial topological photonic crystal, 2 is a trivial topological photonic crystal with Dirac cone degeneracy, 3 is a non-trivial topological photonic crystal, 4 is a trivial topological region, 5 is a trivial topological region with Dirac cone degeneracy, 6 is a non-trivial topological region, 7 is a chiral polarization source, 8 is an antenna, 9 is an enlarged schematic diagram of the chiral polarization source, 10 is a schematic diagram of the topological photonic crystal structure, 11 is a lattice unit of a trivial topological photonic crystal, 12 is a lattice unit of a trivial topological photonic crystal with Dirac cone degeneracy, 13 is a lattice unit of a non-trivial topological photonic crystal, 14 is the distribution of a trivial topological photonic crystal in the first Brillouin photonic band, 15 is the distribution of a trivial topological photonic crystal with Dirac cone degeneracy in the first Brillouin photonic band, and 16 is the distribution of a non-trivial topological photonic crystal in the first Brillouin photonic band. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, a wide-width waveguide beam splitter based on the quantum Hall effect of topological photonic crystals includes a trivial topological photonic crystal 1, a trivial topological photonic crystal 2 with Dirac cone degeneracy, and a non-trivial topological photonic crystal 3. The region formed by the trivial topological photonic crystal 1 is the trivial topological region 4, the region constructed by the trivial topological photonic crystal 2 with Dirac cone degeneracy is the trivial topological region 5 with Dirac cone degeneracy, and the region constructed by the non-trivial topological photonic crystal 3 is the non-trivial topological region 6. The trivial topological region 5 with Dirac cone degeneracy is disposed between the trivial topological region 4 and the non-trivial topological region 6. The waveguide excitation source is a chiral polarization source 7, located in a trivial topological region 5 containing Dirac cone degeneracy. This means it can be located at any position within the Dirac cone degeneracy region 5. Since the source position satisfies the chiral polarization relation, the chiral source should be placed where the chiral polarization Stokes parameter is 1, indicating that the waveguide generated by this chiral source propagates to the right. If the chiral source is placed where the chiral polarization Stokes parameter is -1, the waveguide will be to the left. If the chiral source is placed where the chiral polarization Stokes parameter is 0, the waveguide will propagate in both left and right directions. Figure 1As shown, the dirac cone-degenerate trivial topological region 5 splits into two branches behind the chiral polarization source 7, with each branch extending upwards or downwards before horizontal output. The beam splitter is configured in this way for the following reasons: First, typical boundary modes have no width, while this application is equivalent to directly shifting the waveguide region by 5 lattice layers to achieve the required waveguide width; second, the dirac cone-degenerate trivial topological region 5 in the intermediate layer of this invention resembles a harpoon, exhibiting two 60° angles, thus proving that a large-width waveguide still satisfies robustness; third, the large-width waveguide width is consistent with the number of lattice layers in the intermediate layer; fourth, a trivial topological region 4 and a non-trivial topological region 6 are provided between the two branches, which is essential for achieving unidirectional transmission. In the horizontal direction, the upper side of the dirac cone-degenerate trivial topological region 5 is the non-trivial topological region 6, and the lower side is the trivial topological region 4.

[0026] Figure 9 shows a magnified schematic diagram of the light source. The chiral polarization source includes four antennas 8 perpendicular to the z-axis. Linear polarization sources are added to the antennas 8, and the phases of adjacent linear polarization sources are distributed in increments or decreases of π / 2, thus realizing a chiral polarization source. The antennas 8 are arranged in a square, with a side length of 0.2a, where a is the lattice constant. The antennas 8 are perfectly symmetrical, and such a chiral polarization source is chiral circularly polarized. The topological photonic crystal structure is shown in Figure 10, which shows the general topological photonic crystal structure distribution. The three topological photonic crystals of this invention are derived from the most basic topological photonic crystal, composed of alumina cylinders made of an all-electron dielectric material with a dielectric constant of 7.5, an air background, c being the speed of light in vacuum, and a cylinder radius of 0.12a. The honeycomb lattice contains six hexagonal cylinders, labeled 1, 2, 3, 4, 5, and 6. This invention mainly achieves pseudospin photonic bandgap separation and mode inversion by changing the distance between the next adjacent cylinders. In this invention, the distances from cylinders 1, 3, and 5 to the center of the honeycomb lattice are fixed, while the distances from cylinders 2, 4, and 6 to the center of the honeycomb lattice are changed. The lattice vectors of the topological photonic crystal are used to describe the position of each lattice, with a lattice constant a of 500 nm. 11 is a trivial topological photonic crystal lattice unit, where R1 represents the distance from cylinders 1, 3, and 5 to the lattice center, and R2 represents the distance from cylinders 2, 4, and 6 to the lattice center, where R1 = a / 3 and R2 = a / 3.5. 12 is a trivial topological photonic crystal lattice unit with Dirac cone degeneracy, where R1 = a / 3 and R2 = a / 3.13 is a non-trivial topological photonic crystal lattice unit, where R1 = a / 3 and R2 = a / 2.65. 14 is a trivial topological... The photonic crystals in region 15 are distributed in the first Brillouin zone photonic band structure. Observations show that the photonic pseudospin states p and d are separated. Region 15 is a trivial topological photonic crystal with Dirac cone degeneracy distributed in the first Brillouin zone photonic band structure. Observations show that the photonic pseudospin states p and d are degenerate at the Γ point, resulting in a double Dirac cone. Region 16 is a non-trivial topological photonic crystal distributed in the first Brillouin zone photonic band structure. Observations show that the double Dirac cone reopens and the photonic pseudospin states p and d are reversed. In this invention, the wide-width waveguide states mainly appear in region 5 of the trivial topological photonic crystal with Dirac cone degeneracy. This region mainly consists of 5 layers of trivial topological photonic crystal lattices with Dirac cone degeneracy. The waveguide width of this invention is also 5 lattice constants.

[0027] like Figure 2 As shown, the wide-width waveguide and bulk-edge band structure and energy distribution of the topological photonic crystal heterostructure are illustrated. (a) is a schematic diagram of the wide-width waveguide structure of the topological heterostructure. The bottom layer is a trivial topological region, the middle layer is a trivial topological region with Dirac cone degeneracy, and the top layer is a non-trivial topological region. The middle layer consists of 5 layers of trivial topological photonic crystal lattices with Dirac cone degeneracy. The dashed rectangle represents the supercell of the waveguide structure, used to calculate the bulk-edge photonic band structure. (b) shows the bulk-edge photonic band distribution of the topological photonic crystal heterostructure projected onto the wave vector Kx. Two dispersion curves are observed in the bulk-edge band diagram, indicating the presence of boundary states in the topological heterostructure. The proof mode corresponding to Kx = 0.04 is selected, with proof frequency f. A Observations revealed that the electric field amplitude was mainly uniformly distributed in the middle layer, indicating that the boundary states here are a wide, uniformly distributed waveguide. See the first small rectangle on the right in Figure (b). This is based on the eigenmode calculated from the supercell. Through this electric field mode distribution, it can be seen that the electromagnetic waves are mainly uniformly distributed and concentrated in the middle region, which is a trivial topological region containing Dirac cone degeneracy. Figure (c) shows the wide-width waveguide electric field energy distribution of the topological photonic crystal heterostructure, where the electric field energy distribution is represented by... The calculations yielded that ε(r) and E... Z(r) represents the dielectric constant and electric field Ez distribution as a function of position, respectively. Observations show that the waveguide energy is mainly uniformly distributed in the trivial topological region with Dirac cone degeneracy in the middle layer. Similarly, the Poynting vector is used here. Characterizing the electric field energy distribution, the distribution of arrows also indicates that the waveguide energy is uniformly distributed in the middle layer. These represent the real part of the electric field, the electric field strength, and the conjugate of the magnetic field strength, respectively. (c) shows that a unidirectional wide-width waveguide is obtained in the sandwich structure of Figure (a). First, a sandwich structure is constructed using three topological photonic crystals according to Figure (a). Then, the rectangular unit marked with dashed lines in Figure (a), i.e., the supercell, is calculated. Finite element analysis is performed on the supercell to obtain the projected photonic bulk-edge band along the wave vector Kx direction in the first Brillouin zone, as shown in Figure (b). Figure (b) reveals two boundary state dispersion curves in the photonic bulk band. Based on the bulk-edge correspondence, two boundary states appear in the topological heterojunction. The projected photonic band gap is the working bandwidth of the unidirectional waveguide boundary states. Finally, a chiral source excitation is used to generate a wide-width waveguide unidirectional boundary state in the topological heterojunction. (d) shows the normalized electric field amplitude distribution along the y-axis of the wide-width waveguide in the topological heterostructure, as shown by the dashed line in (a). The normalized electric field amplitude distribution along the y-axis of the wide-width waveguide was calculated. It was observed that the waveguide energy is mainly uniformly distributed in the middle layer and the waveguide width is equal to the number of lattice layers in the middle layer.

[0028] like Figure 3 The following are simulation examples of the present invention. (a) shows the electric field energy distribution of the wide-width waveguide beamsplitter in the topological photonic crystal. A wide-width waveguide beamsplitter is constructed based on the proposed waveguide. (b) shows the Poynting vector distribution of the wide-width waveguide beamsplitter. Observation reveals that the electric field energy of the wide-width waveguide beamsplitter in the topological photonic crystal is mainly uniformly distributed in a trivial topological region containing Dirac cone degeneracy. When passing through two 60° angle defects, the electromagnetic wave can still bypass the obstacle and transmit steadily in one direction, indicating that the waveguide beamsplitter of the present invention has topological protection robustness. (c) shows the calculated normalized electric field amplitude distribution of the wide-width waveguide beamsplitter along the y-axis direction. Lines 1 and 2 are shown as dashed lines in (a). Observation reveals that the waveguide distribution of the two beamsplitter channels is consistent and the waveguide width is 5a. In addition, observation reveals that even with a waveguide transmission distance of 23a, the electric field energy of the beamsplitter channel is about half that of the main channel, indicating that the wide-width waveguide beamsplitter has high transmission efficiency. The light source is placed in the main channel, with sub-beam channels on both sides.

[0029] Therefore, this invention realizes a topological wideband waveguide beam splitter based on the quantum spin Hall effect.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wide-width waveguide beam splitter based on a topological photonic crystal using the quantum Hall effect, characterized in that, It includes a trivial topological region (4), a trivial topological region (5) with Dirac cone degeneracy, and a non-trivial topological region (6). The trivial topological region (5) with Dirac cone degeneracy is located between the trivial topological region (4) and the non-trivial topological region (6). A trivial topological photonic crystal (1) is uniformly arranged in the trivial topological region (4). A trivial topological photonic crystal (2) with Dirac cone degeneracy is uniformly arranged in the trivial topological region (5). A non-trivial topological photonic crystal (3) is uniformly arranged in the non-trivial topological region (6). A chiral polarization source (7) is provided in the trivial topological region (5) with Dirac cone degeneracy. The trivial topological region (5) containing Dirac cone degeneracy splits into two branches on the back side of the chiral polarization source (7). The two branches extend downward or downward and then output horizontally. A trivial topological region (4) and a non-trivial topological region (6) are provided between the two branches.

2. The wide-width waveguide beamsplitter based on the quantum Hall effect topological photonic crystal according to claim 1, characterized in that, The shape of the dirac cone degenerate trivial topological region (5) is harpoon-shaped; the upper side of the dirac cone degenerate trivial topological region (5) is a non-trivial topological region (6), and the lower side is a trivial topological region (4).

3. The wide-width waveguide beam splitter based on the quantum Hall effect topological photonic crystal according to claim 1 or 2, characterized in that, The trivial topological photonic crystal (1), the Dirac cone-degenerate trivial topological photonic crystal (2), and the non-trivial topological photonic crystal (3) are all composed of alumina cylinders, which are all-electron dielectric materials with a dielectric constant of 7.

5. The background is air, and the cylinder radius is... ;in, Let be the lattice constant and take .

4. The wide-width waveguide beamsplitter based on the quantum Hall effect topological photonic crystal according to claim 3, characterized in that, The trivial topological photonic crystal (1), the Dirac cone-degenerate trivial topological photonic crystal (2), and the non-trivial topological photonic crystal (3) are all composed of a honeycomb lattice. The honeycomb lattice contains 6 regular hexagonal cylinders. By changing the distance between the next adjacent cylinders, the separation of pseudo-spin photonic band gaps and mode inversion can be achieved.

5. The wide-width waveguide beamsplitter based on the quantum Hall effect topological photonic crystal according to claim 4, characterized in that, The distance from a set of adjacent cylinders of the lattice unit of the trivial topological photonic crystal to the lattice center. =a / 3, the distance of the other set of adjacent cylinders from the lattice center =a / 3.5; lattice unit cells of a trivial topological photonic crystal containing Dirac cone degeneracy In the lattice unit cells of nontrivial topological photonic crystals .

6. The wide-width waveguide beamsplitter based on the quantum Hall effect topological photonic crystal according to claim 5, characterized in that, Photonic pseudospin states in the first Brillouin zone photonic bandgap distribution of a trivial topological photonic crystal with Dirac cone degeneracy , State in Point degeneracy results in the appearance of double Dirac cones; wide-width waveguide states mainly appear in the trivial topological region (5) consisting of 5 layers of trivial topological photonic crystals with Dirac cone degeneracy; in the supercell of the sandwich structure containing the trivial topological region (4), the trivial topological region (5) with Dirac cone degeneracy and the non-trivial topological region (6), the electric field amplitude is uniformly distributed in the trivial topological photonic crystal region (5) with Dirac cone degeneracy, and the electromagnetic waves are uniformly distributed and concentrated in the trivial topological region (5) with Dirac cone degeneracy; the waveguide energy is uniformly distributed in the trivial topological region (5) with Dirac cone degeneracy and the waveguide width is equal to the number of lattice layers in the middle layer.

7. The wide-width waveguide beamsplitter based on the quantum Hall effect topological photonic crystal according to any one of claims 4-6, characterized in that, The electric field energy is mainly uniformly distributed in the trivial topological region containing Dirac cone degeneracy. Even when passing through two defects at 60° angles, the electromagnetic wave can still bypass the obstacle and propagate steadily in one direction. The waveguide distribution of the beam splitting channels containing the two branches is consistent, and the waveguide width is... Even if the waveguide transmission distance is The electric field energy of the beam splitter channel is about half that of the electric field energy of the main channel where the chiral polarization source (7) is located.

8. The wide-width waveguide beamsplitter based on the quantum Hall effect topological photonic crystal according to claim 7, characterized in that, The chiral polarization source (7) includes four antennas (8) perpendicular to the z-axis. Linear polarization sources are added to the antennas (8), and the phases of adjacent linear polarization sources are equal. Increasing or decreasing distribution.

9. The wide-width waveguide beamsplitter based on the quantum Hall effect topological photonic crystal according to claim 8, characterized in that, The chiral polarization source (7) is chiral circularly polarized, and the antennas (8) are arranged in a square, with the side length of the square being... ,in, is the lattice constant.

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