Perimeter-variable one-way coupling topology photon cavity based on scatterer

Abstract

The invention discloses a scatterer-based one-way coupling topology photon cavity with variable perimeter. The device comprises a shielding case, and an electrospinning continuous medium layer and an air layer which have a chiral surface state at the junction of the shielding case and the electrospinning continuous medium layer; a cylindrical rotary electric continuous medium is also distributed in the air layer, and a first scatterer of an isotropic medium exists between the cylindrical rotary electric continuous medium and an interface where the chiral surface state is located; and air exists at the junction of the first scatterer and the cylindrical rotating electric continuous medium and the chiral surface state. The one-way coupling topological photon cavity with the variable perimeter gets rid of dependence on strict periodic conditions, and can realize a one-way coupling effect under the condition of photon cavities with different perimeters. While the scattering suppression transmission characteristic of the chiral boundary state is realized, the unidirectional coupling between the chiral boundary state and the scatterer is closely related to the direction of an external magnetic field in the rotary electric continuous medium. Furthermore, by changing the radius size and the magnetic field direction of the photon cavity, the one-way coupling topology photon cavity with variable perimeter and controllable coupling direction is realized.

Description

Technical Field

[0001] This invention belongs to the field of optical device technology and relates to a photonic cavity topology device induced by the coupling effect between an optical waveguide mode and a scatterer, specifically a unidirectional coupling topology photonic cavity based on the variable perimeter of the scatterer. Background Technology

[0002] Research in topological photonics originated from the discovery of topological phases in condensed matter physics and has developed into a cutting-edge field that intersects and integrates topological physics and photonics. In recent years, research on topological phases in topological photonics has made a series of advances, such as Weyl points, topological insulators, and chiral bulk states. Based on the chiral surface states in topological phases, topological photonic devices with different functions have been designed and realized, such as topological photonic waveguides, topological photonic beamsplitters, and topological photonic cavities, providing new solutions for scattering suppression of light transmission.

[0003] In recent years, different types of topological photonic cavities have been designed and realized based on photonic crystal platforms. For example, topological photonic cavities of arbitrary shapes have been realized in systems with broken time-reversal symmetry, providing a new control scheme for the interaction between light and matter. However, photonic crystals usually require strict periodicity conditions and carefully designed unit cell structures, which limits the structural tunability of topological photonic cavities.

[0004] Unlike the aforementioned photonic crystals, under the long-wavelength approximation, cycloelectric continuous media are homogeneous bulk materials described by relatively equivalent permittivity and permeability tensors, and their non-zero cycloelectric parameters break time-reversal symmetry. Furthermore, the nontrivial topological properties in cycloelectric continuous media are induced by magneto-optical effects. In recent years, cycloelectric continuous media have been studied for applications in various functional topological photonic devices, such as the design of topological photonic waveguides, topological photonic isolators, and topological photonic beamsplitters. However, current research on unidirectional transmission topological photonic devices based on cycloelectric continuous media relies on limited methods. Most studies focus on topological photonic systems with single structures and specific structural dimensions, while research on topological photonic devices with tunable perimeters and controllable coupling directions regarding the interaction between chiral surface states and scatterers is rarely reported, such as the design and realization of a unidirectionally coupled topological photonic cavity with variable perimeters. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies and provide a unidirectionally coupled topological photonic cavity based on a scatterer with a variable perimeter. Specifically, it is a topological photonic cavity that can realize a variable perimeter and controllable coupling direction, so as to provide a design scheme for a unidirectionally coupled topological photonic cavity functional device with a variable perimeter.

[0006] This invention provides a unidirectionally coupled topological photonic cavity based on a scatterer with a variable perimeter, comprising a shield and a spool-electro-continuous medium layer and an air layer respectively disposed within the shield, wherein chiral surface states exist at the boundary between the spool-electro-continuous medium layer and the air layer; wherein the topological properties of the spool-electro-continuous medium layer and the air layer are different.

[0007] The air layer is further provided with at least one cylindrical spool-electroelectric continuous medium, and there is a first scatterer of an isotropic medium between the cylindrical spool-electroelectric continuous medium and the interface where the chiral surface state is located.

[0008] Air exists at the interface between the first scatterer, the cylindrical spool-electro-continuous medium, and the chiral surface state.

[0009] Preferably, an excitation point source is also provided at the interface where the chiral surface state is located.

[0010] Preferably, a cylindrical air cavity is further provided within the spooloelectric continuous medium layer. More preferably, a second scatterer of isotropic medium exists between the cylindrical air cavity and the interface where the chiral surface state is located, and a spooloelectric continuous medium exists between the second scatterer and the interface where the cylindrical air cavity and the chiral surface state are located.

[0011] Preferably, the number of cylindrical air cavities is the same as or different from the number of cylindrical spool-electro-continuous media.

[0012] Preferably, the chiral surface states generated at the interface between the spool-electro-continuous medium layer and the air layer are coupled with the first scatterer, thereby realizing the unidirectional coupled photonic cavity function.

[0013] Preferably, the gyroelectric continuous medium is a bulk material that can be described by an equivalent relative permittivity tensor and a permeability tensor, and its non-trivial topological response is induced by non-zero gyroelectric parameters.

[0014] Preferably, the spooloelectric continuous medium layer has a sharp defect on the interface side where the chiral surface states are located, which is used to test the robust transport characteristics of the chiral surface states.

[0015] Preferably, the unidirectional coupling direction of the photonic cavity can be controlled by changing the radius (i.e., by making the circumference variable) of the cylindrical spool-electro-continuous medium or the cylindrical air cavity and the direction of the magnetic field.

[0016] Preferably, under the condition that the magnetic field conditions and operating frequency remain unchanged, the unidirectional coupling efficiency of the photonic cavity can be adjusted by controlling the radius of the cylindrical spool-electro-continuous medium or the cylindrical air cavity.

[0017] Preferably, with the radius and operating frequency of the cylindrical spool-electro-continuous medium or the cylindrical air cavity remaining unchanged, the unidirectional coupling direction of the photonic cavity is changed by altering the direction of the magnetic field.

[0018] Preferably, the magnetic field parameter g of the topological photonic cavity is greater than 0.

[0019] Compared to existing topological photonic cavities that typically require strict periodic conditions and carefully designed unit cell structures, this invention has the following advantages:

[0020] This invention provides a unidirectionally coupled topological photonic cavity with variable perimeter, freeing it from dependence on strictly periodic conditions and enabling unidirectional coupling effects under photonic cavity conditions of different perimeters. While achieving chiral boundary state scattering suppression transmission characteristics, the unidirectional coupling between the chiral boundary states and the scatterer is closely related to the direction of the applied magnetic field in the cyclotronic continuous medium. Furthermore, by changing the radius and magnetic field direction of the photonic cavity, a unidirectionally coupled topological photonic cavity with variable perimeter and controllable coupling direction can be realized. Attached Figure Description

[0021] Figure 1 Two-dimensional band diagrams and propagation patterns of the cycloelectric continuous medium of the present invention under different interface configurations are shown, where (a)-(b) are two-dimensional band diagrams and (c)-(d) are transmission patterns;

[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of a unidirectionally coupled photonic cavity based on a scatterer, provided in Embodiment 1 of the present invention.

[0023] Figure 3 This is a schematic diagram of the cross-sectional structure of a unidirectional coupled topological photonic cavity based on a scatterer with variable perimeter provided in Embodiment 2 of the present invention.

[0024] Figure 4 This is a schematic diagram of the cross-sectional structure of a unidirectional coupled topological photonic cavity based on a scatterer with variable perimeter provided in Embodiment 3 of the present invention.

[0025] Figure 5 This is a schematic diagram of the cross-sectional structure of a unidirectionally coupled photonic cavity based on a scatterer with variable perimeter provided in Embodiment 4 of the present invention.

[0026] Figure 6 This is a schematic diagram of the cross-sectional structure of a unidirectionally coupled topological photonic cavity based on a scatterer, provided in Embodiment 5 of the present invention.

[0027] Figure 7 This is a schematic diagram of the cross-sectional structure of a unidirectionally coupled photonic cavity based on a scatterer with variable perimeter provided in Embodiment 6 of the present invention.

[0028] Figure 8 This invention presents the unidirectional coupling situation and control process under photonic cavity conditions with different perimeters, where (a)-(e) represent the unidirectional coupling situation, and (f)-(g) represent the electric field distribution of the unidirectional coupling topological cavity when the magnetic field direction is changed;

[0029] Figure 9 This invention is used to test the robustness of defects and the effect of scatterers induced by topological photonic cavities. (a)-(c) are the electric field distribution diagrams of the topological photonic cavities under different scatterer configurations of the invention.

[0030] Reference numerals in the attached figures: 1. Shielding cover; 2. Electro-electric continuous medium layer; 2-1. Cylindrical air cavity; 2-2. Second scatterer; 3. Air layer; 3-1. Cylindrical electro-electric continuous medium; 3-2. First scatterer; 4. Chiral surface state; 5. Excitation point source. Detailed Implementation

[0031] The technical solution of the present invention will be further explained below with reference to the figures.

[0032] This invention relates to a variable-perimeter unidirectional coupled topological photonic cavity device composed of air, a scatterer, and a cycloelectric continuous medium. The nontrivial topological properties of the cycloelectric continuous medium are induced by the magneto-optical effect, and chiral surface states with unidirectional propagation exist at its boundary with air. By adding an isotropic scatterer in the gap between air and the cycloelectric continuous medium, the chiral surface states can be unidirectionally coupled to the topological photonic cavity. This invention enables the realization of a topological photonic cavity device with variable perimeter and coupling direction by changing the radius and magnetic field direction of the topological photonic cavity. This invention is applicable to topological functional devices such as topological photonic cavities, topological photonic routes, and topological photonic beamsplitters with variable structural size, providing greater flexibility for designing and implementing a variable-perimeter unidirectional coupled topological photonic cavity.

[0033] Example 1:

[0034] See appendix Figure 2 This embodiment is based on a unidirectionally coupled photonic cavity with a variable perimeter of the scatterer, including a shield 1, and a spool-electro-continuous medium layer 2 and an air layer 3 respectively disposed inside the shield 1, and a chiral surface state 4 exists at the interface between the spool-electro-continuous medium layer 2 and the air layer 3; wherein, the topological properties of the spool-electro-continuous medium layer 2 and the air layer 3 are different; an excitation point source 5 is also disposed at the interface where the chiral surface state 4 is located.

[0035] A cylindrical spool-electroelectric continuous medium 3-1 is also arranged in the air layer 3, and there is a first scatterer 3-2 of isotropic medium between the interface of the cylindrical spool-electroelectric continuous medium 3-1 and the chiral surface state 4; there is air at the interface between the first scatterer 3-2 and the cylindrical spool-electroelectric continuous medium 3-1 and the chiral surface state 4.

[0036] A cylindrical air cavity 2-1 is further arranged within the spooloelectric continuous medium layer 2. A second scatterer 2-2 of isotropic medium exists between the cylindrical air cavity 2-1 and the interface of the chiral surface state 4. A spooloelectric continuous medium exists between the second scatterer 2-2 and the interface of the cylindrical air cavity 2-1 and the chiral surface state 4. In this embodiment, the cylindrical air cavity 2-1 and the cylindrical spooloelectric continuous medium 3-1 have the same dimensions, i.e., equal perimeters.

[0037] When the magnetic field parameter g > 0, the chiral surface state 4 generated at the junction of the spool-electro-continuous medium layer 2 and the air layer 3 couples with the first scatterer 3-2, thereby realizing the unidirectional coupling photonic cavity function.

[0038] The spool-electrolyte continuous medium layer 2 and the cylindrical spool-electrolyte continuous medium 3-1 employ a spool-electrolyte continuous medium that is a bulk material that can be described by an equivalent relative permittivity tensor and a permeability tensor. Its non-trivial topological response is induced by non-zero spool-electrolyte parameters, such as yttrium iron garnet.

[0039] By changing the radius (i.e., by making the perimeter variable) of the cylindrical spool-electro-continuous medium 3-1 or the cylindrical air cavity 2-1 and the direction of the magnetic field, the unidirectional coupling direction of the photonic cavity can be controlled.

[0040] Under constant magnetic field conditions and operating frequency, the unidirectional coupling efficiency of the photonic cavity can be adjusted by regulating the radius of the cylindrical spool-electro-continuous medium 3-1 or the cylindrical air cavity 2-1.

[0041] With the radius and operating frequency of the cylindrical spool-electro-continuous medium 3-1 or the cylindrical air cavity 2-1 remaining unchanged, the unidirectional coupling direction of the photonic cavity can be changed by altering the direction of the magnetic field.

[0042] Example 2:

[0043] See appendix Figure 3 In this embodiment, based on the variable perimeter unidirectional coupling topological photonic cavity of the scatterer, the bottom diameter of the cylindrical spool-electro-continuous medium 3-1 is reduced while other dimensions remain unchanged.

[0044] Example 3:

[0045] See appendix Figure 4 This embodiment is based on a unidirectionally coupled photonic cavity with a variable perimeter of the scatterer, including a shield 1, and a spool-electro-continuous medium layer 2 and an air layer 3 respectively disposed inside the shield 1, and a chiral surface state 4 exists at the interface between the spool-electro-continuous medium layer 2 and the air layer 3; wherein, the topological properties of the spool-electro-continuous medium layer 2 and the air layer 3 are different; an excitation point source 5 is also disposed at the interface where the chiral surface state 4 is located.

[0046] The air layer 3 is further provided with two cylindrical spool-electrostatic continuous media 3-1 of unequal size, and there is a first scatterer 3-2 of isotropic medium between the interface of the cylindrical spool-electrostatic continuous media 3-1 and the chiral surface state 4; there is air between the first scatterer 3-2 and the interface of the cylindrical spool-electrostatic continuous media 3-1 and the chiral surface state 4.

[0047] The spool-electromagnetic continuous medium layer 2 is also provided with two cylindrical air cavities 2-1 of unequal size.

[0048] When the magnetic field parameter g > 0, the chiral surface state 4 generated at the junction of the spool-electro-continuous medium layer 2 and the air layer 3 couples with the first scatterer 3-2, thereby realizing the unidirectional coupling photonic cavity function.

[0049] The spool-electrolyte continuous medium layer 2 and the cylindrical spool-electrolyte continuous medium 3-1 employ a spool-electrolyte continuous medium that is a bulk material that can be described by an equivalent relative permittivity tensor and a permeability tensor. Its non-trivial topological response is induced by non-zero spool-electrolyte parameters, such as yttrium iron garnet.

[0050] By changing the radius (i.e., by making the perimeter variable) of the cylindrical spool-electro-continuous medium 3-1 or the cylindrical air cavity 2-1 and the direction of the magnetic field, the unidirectional coupling direction of the photonic cavity can be controlled.

[0051] Under constant magnetic field conditions and operating frequency, the unidirectional coupling efficiency of the photonic cavity can be adjusted by regulating the radius of the cylindrical spool-electro-continuous medium 3-1 or the cylindrical air cavity 2-1.

[0052] With the radius and operating frequency of the cylindrical spool-electro-continuous medium 3-1 or the cylindrical air cavity 2-1 remaining unchanged, the unidirectional coupling direction of the photonic cavity can be changed by altering the direction of the magnetic field.

[0053] Example 4:

[0054] See appendix Figure 5 This embodiment is based on a unidirectionally coupled photonic cavity with a variable perimeter of the scatterer, including a shield 1, and a spool-electro-continuous medium layer 2 and an air layer 3 respectively disposed inside the shield 1, and a chiral surface state 4 exists at the interface between the spool-electro-continuous medium layer 2 and the air layer 3; wherein, the topological properties of the spool-electro-continuous medium layer 2 and the air layer 3 are different; an excitation point source 5 is also disposed at the interface where the chiral surface state 4 is located.

[0055] The air layer 3 is further provided with three cylindrical spool-electrolyte continuous media 3-1, and there is a first scatterer 3-2 of an isotropic medium between the interface of the first two cylindrical spool-electrolyte continuous media 3-1 at the top and the chiral surface state 4; there is air between the first scatterer 3-2 and the interface of the cylindrical spool-electrolyte continuous media 3-1 and the chiral surface state 4.

[0056] When the magnetic field parameter g > 0, the chiral surface state 4 generated at the junction of the spool-electro-continuous medium layer 2 and the air layer 3 couples with the first scatterer 3-2, thereby realizing the unidirectional coupling photonic cavity function.

[0057] The spoololite continuous medium layer 2 has a sharp defect on the interface side where the chiral surface state 4 is located, which is used to test the robust transport characteristics of the chiral surface state 4. In this embodiment, a square defect exists.

[0058] The spool-electrolyte continuous medium layer 2 and the cylindrical spool-electrolyte continuous medium 3-1 employ a spool-electrolyte continuous medium that is a bulk material that can be described by an equivalent relative permittivity tensor and a permeability tensor. Its non-trivial topological response is induced by non-zero spool-electrolyte parameters, such as yttrium iron garnet.

[0059] By changing the radius of the cylindrical spool-electro-continuous medium 3-1 (i.e., by changing the circumference) and the direction of the magnetic field, the unidirectional coupling direction of the photonic cavity can be controlled.

[0060] Under constant magnetic field conditions and operating frequency, the unidirectional coupling efficiency of the photonic cavity can be adjusted by regulating the radius of the cylindrical spool-electro-continuous medium 3-1.

[0061] With the radius and operating frequency of the cylindrical spool-electro-continuous medium 3-1 remaining constant, the unidirectional coupling direction of the photonic cavity can be changed by altering the direction of the magnetic field.

[0062] Example 5:

[0063] See appendix Figure 6 In this embodiment, based on the variable perimeter unidirectional coupling topological photonic cavity of the scatterer, in addition to the scatterer of embodiment 4, there is a first scatterer 3-2 of isotropic medium between each of the three cylindrical spool-electro-continuous media 3-1 and the chiral surface state 4, while the rest remains unchanged.

[0064] Example 6:

[0065] See appendix Figure 7 In this embodiment, based on the variable perimeter unidirectional coupling topological photonic cavity of the scatterer, the first scatterer 3-2 with an isotropic medium is not set between the interface of the middle cylindrical spool-electro-continuous medium 3-1 and the chiral surface state 4, while the first scatterer 3-2 with an isotropic medium is set between the interfaces of the other cylindrical spool-electro-continuous medium 3-1 and the chiral surface state 4, and everything else remains the same.

[0066] In numerical electromagnetic simulations, topological photonic cavity systems consist of air, scatterers, and gyroelectric continuums with varying topological properties. The following examples use the dielectric parameter ε of the gyroelectric continuum. t =1.5, g=0.7, permeability constant parameter μ t=1, μ z =1-1 / ω 2 For example, taking a chiral surface state with unidirectional propagation at the boundary between the cycloelectric continuous medium and air as a reference, the unidirectional coupling is achieved by the interaction between the chiral surface state and the scatterer. The unidirectional coupling between the chiral surface state and the scatterer can be achieved under photonic cavity conditions of different perimeters. The chiral surface state with scattering-suppressed propagation can be excited by a point source located at the interface between the cycloelectric continuous medium and air.

[0067] Figure 1 This is a two-dimensional band structure diagram of the cycloelectric continuous medium of the present invention under different interface configurations. When the cycloelectric continuous medium is in direct contact with air, a chiral surface state is generated in the common band gap of its two-dimensional band structure, such as... Figure 1 As shown by the purple line in (a). When a scatterer is added between the cycloelectric continuous medium and the air, the two-dimensional band structure of the scatterer includes the chiral surface states. These chiral surface states then become leakage modes capable of leaking towards one side of the scatterer, as shown in... Figure 1 As shown in (b). This invention further simulates the specific distribution of chiral surface states and leakage modes based on changes in the configuration of the cycloelectric continuous medium interface. When only air is in direct contact with the cycloelectric continuous medium, unidirectionally transported chiral surface states exist at its boundary, such as... Figure 1 As shown in (c). When a scatterer is added to the air and cyclotron continuum, the mode diffuses into the scatterer, as shown in (c). Figure 1 As shown in (d).

[0068] like Figure 8 In diagram (a), when the magnetic field parameter g > 0 and the operating frequency ω = 0.7, and the radius of the cylindrical electro-hydraulic continuous medium is 8.6 times the wavelength corresponding to this operating frequency, it is clear from the color distribution of the electric field intensity in the diagram that the electric field intensity in the coupled photonic cavity is significantly less than that in the waveguide. Figure 8 In diagram (b), when the magnetic field parameter g > 0 and the operating frequency ω = 0.7, the radius of the cylindrical spool-electro-continuous medium is 7.1 times the wavelength corresponding to this operating frequency. At this point, it is clear from the color distribution of the electric field intensity in the diagram that the electric field intensity in the coupled photonic cavity is significantly greater than that of the waveguide. Figure 8 In diagram (c), when the magnetic field parameter g > 0 and the operating frequency ω = 0.7, the radius of the cylindrical gyroelectric continuous medium is 5.7 times the wavelength corresponding to this operating frequency. At this point, it is clear from the color distribution of the electric field intensity in the diagram that the electric field intensity in the coupled photonic cavity is less than the intensity of the waveguide. Figure 8In diagram (d), when the magnetic field parameter g > 0 and the operating frequency ω = 0.7, the radius of the cylindrical spool-electro-continuous medium is 4.3 times the wavelength corresponding to this operating frequency. At this point, it is clear from the color distribution of the electric field intensity in the diagram that the electric field intensity in the coupled photonic cavity is slightly greater than that of the waveguide. Figure 8 In diagram (e), when the magnetic field parameter g > 0 and the operating frequency ω = 0.7, the radius of the cylindrical spool-electro-continuous medium is 2.9 times the wavelength corresponding to this operating frequency. At this point, it is clear from the color distribution of the electric field intensity in the diagram that the electric field intensity in the coupled photonic cavity is significantly less than that in the waveguide. Figure 8 (a)- Figure 8 As shown in Figure (e), simulations present the electric field distribution of a unidirectionally coupled topological photonic cavity under different photonic cavity perimeters. From the figure, it can be seen that this invention can achieve the interaction between chiral surface states and scatterers under photonic cavity conditions with different perimeters, thereby coupling different chiral surface states into the photonic cavity and realizing a topologically coupled photonic cavity with variable perimeter. Furthermore, as... Figure 8 In (f), when the magnetic field parameter g < 0 and the operating frequency ω = 0.7, the radius of the cylindrical gyroelectric continuous medium is... Figure 8 (b) When they are equal, it is clear from the color distribution of the electric field intensity in the figure that the electric field intensity in the coupled photonic cavity is significantly less than that in the waveguide. Furthermore, as... Figure 8 In the case of magnetic field parameter g < 0 and operating frequency ω = 0.7, chiral surface states cannot couple into the air cavity when no scatterer is present. However, when a scatterer is present, they can couple into the gyroelectric continuous medium, and the electric field intensity in the coupled photonic cavity is significantly lower than that of the waveguide. This invention also allows for controllability of the coupling direction between chiral surface states and scatterers by changing the direction of the magnetic field in the gyroelectric continuous medium, providing a theoretical basis for designing and realizing topological photonic cavities with variable perimeters and controllable coupling directions.

[0069] Figure 9 To test the scattering suppression, transmission, and coupling of chiral surface states in the topological photonic cavity of this invention, this embodiment does not have a cylindrical air cavity in the spooloelectric continuous medium layer, and the air layer has three cylindrical spooloelectric continuous media. With the magnetic field parameter g > 0 and the operating frequency ω = 0.7, Figure 9Figure (a) shows that both the first cylindrical spool-electroelectric continuous medium 1-1 and the second cylindrical spool-electroelectric continuous medium 1-2 have scatterers at the interface with the chiral surface states. However, the third cylindrical spool-electroelectric continuous medium 1-3 does not have a scatterer at the interface with the chiral surface states. From the corresponding electric field intensity distribution diagram, it can be seen that the chiral surface states only undergo unidirectional coupling with the scatterers at the first and second cylindrical spool-electroelectric continuous mediums 1-1 and 1-2, while there is no mode distribution in the third cylindrical spool-electroelectric continuous medium 1-3. This is because when scatterers exist between the first two cylindrical spool-electroelectric continuous media and the chiral surface states, it is found that partial effective coupling from the first cylindrical spool-electroelectric continuous medium 1-1 to the second cylindrical spool-electroelectric continuous medium 1-2 can be achieved through the coupling effect between the chiral surface states and the scatterers.

[0070] Figure 9 Figure (b) shows that the first cylindrical spool-electroelectric continuous medium 2-1, the second cylindrical spool-electroelectric continuous medium 2-2, and the third cylindrical spool-electroelectric continuous medium 2-3 all have scatterers at the interfaces with the chiral surface states. From the corresponding electric field intensity distribution diagram, it can be seen that the scatterers at the three media of the chiral surface state undergo unidirectional coupling. This is because when there are scatterers between the three cylindrical spool-electroelectric continuous media and the chiral surface state, it is found that the coupling between the chiral surface state and the scatterers can achieve effective coupling of the three scatterers.

[0071] Figure 9 Figure (c) shows that both the first cylindrical spool-electroelectric continuous medium 3-1 and the third cylindrical spool-electroelectric continuous medium 3-2 have scatterers at their interfaces with the chiral surface states. However, the second cylindrical spool-electroelectric continuous medium 3-2 does not have a scatterer at its interface with the chiral surface states. The corresponding electric field intensity distribution diagram shows that the chiral surface states only undergo unidirectional coupling with the scatterers at the first and third cylindrical spool-electroelectric continuous mediums 3-1 and 3-3, while there is no mode distribution in the second cylindrical spool-electroelectric continuous medium 3-2. This is because when scatterers exist between the first and third cylindrical spool-electroelectric continuous media and the chiral surface states, it is found that partial effective coupling from the first cylindrical spool-electroelectric continuous medium 3-1 to the third cylindrical spool-electroelectric continuous medium 3-3 can be achieved through the coupling between the chiral surface states and the scatterers.

[0072] In addition, through Figure 9 (a)- Figure 9 The simulation results in (c) show that the mode field distribution of the chiral surface states does not change before and after bypassing the square defect, further proving the scattering suppression characteristics of the chiral surface states.

Claims

1. A unidirectionally coupled topological photonic cavity based on a scatterer with variable perimeter, characterized in that, It includes a shield, and a cycloelectric continuous medium layer and an air layer respectively arranged inside the shield, with chiral surface states existing at the boundary between the cycloelectric continuous medium layer and the air layer; wherein the topological properties of the cycloelectric continuous medium layer and the air layer are different. The air layer is further provided with at least one cylindrical spool-electroelectric continuous medium, and there is a first scatterer of an isotropic medium between the cylindrical spool-electroelectric continuous medium and the interface where the chiral surface state is located. Air exists at the interface between the first scatterer, the cylindrical spool-electro-continuous medium, and the chiral surface state.

2. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 1, characterized in that, Excitation point sources are also arranged at the interface where the chiral surface states are located.

3. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 1, characterized in that, The spool-electromagnetic continuous medium layer is also provided with cylindrical air cavities.

4. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 3, characterized in that, Between the cylindrical air cavity and the interface where the chiral surface state is located, there is also a second scatterer of an isotropic medium, and there is a gyroelectric continuous medium between the second scatterer and the interface where the cylindrical air cavity and the chiral surface state are located.

5. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 1, characterized in that, The chiral surface states generated at the interface between the spool-electro-continuous medium layer and the air layer couple with the first scatterer, thereby realizing the unidirectional coupling photonic cavity function.

6. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 1, characterized in that, The gyroelectric continuous medium is a bulk material that can be described by an equivalent relative permittivity tensor and a permeability tensor, and its non-trivial topological response is induced by non-zero gyroelectric parameters.

7. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 1, characterized in that, The interface between the electro-electro-continuous medium layer and the chiral surface states has defects.

8. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 1, characterized in that, By changing the radius and magnetic field direction of a cylindrical spool-electromagnetic continuous medium or a cylindrical air cavity, the unidirectional coupling direction of the photonic cavity can be controlled.

9. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter as described in claim 8, characterized in that, Under constant magnetic field conditions and operating frequency, the unidirectional coupling efficiency of the photonic cavity can be adjusted by controlling the radius of the cylindrical spool-electro-continuous medium or the cylindrical air cavity.

10. The unidirectionally coupled photonic cavity based on a scatterer with variable perimeter according to claim 8, characterized in that, With the radius and operating frequency of the cylindrical spool-electro-continuous medium or the cylindrical air cavity remaining constant, the unidirectional coupling direction of the photonic cavity can be changed by altering the direction of the magnetic field.

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