Intermediate infrared range topology resonant cavity for realizing dual-band topology edge state and design method thereof
By introducing the method of scatterer rotational symmetry failure and lattice splicing in the honeycomb lattice structure of the mid-infrared band, a topological resonator cavity that realizes dual-band operation is designed, solving the limitations of the single frequency band of the mid-infrared band topological photonics system in the prior art, and achieving efficient dual-band operation and robustness to defects.
Patent Information
- Application Number
- CN202510176376.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2025-06-03
AI Technical Summary
Most of the existing topological photonics systems in the mid-infrared band are limited to a single frequency band, limiting their diversity and bandwidth operation capabilities.
By introducing the method of scatterer rotational symmetry failure and lattice splicing in the honeycomb lattice structure, a topological resonator cavity that achieves dual-band operation is designed. Specific steps include designing the energy valley photonic crystal, realizing different energy valley photonic crystals through the rotation of the scatterer, splicing to form topologically protected edge states, designing supercell structures and Ω waveguide structures, and building a dual-band triangular resonant cavity.
It realizes dual-band operation in the mid-infrared range, high-quality factors and robustness to defects, significantly improving the operating bandwidth and flexibility of the resonant cavity.
Smart Images
Figure CN120085458A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photonic devices and systems, and particularly to a mid-infrared range topological resonator for realizing dual-band topological edge states and a design method thereof. Background Art
[0002] The mid-infrared band has unique importance and finds extensive applications in multiple fields. The mid-infrared spectral range includes numerous "fingerprint" spectral lines, which are helpful for detecting trace gases such as methane, carbon dioxide, carbon monoxide, and formaldehyde. Efficient and compact mid-infrared light sources also have important potential in industrial process control, clinical respiratory analysis, free-space optical communication, infrared scene projection, and chemical and biological threat identification. Therefore, the development of photonic devices that can operate efficiently in the mid-infrared range is crucial for promoting these applications.
[0003] Topological photonic systems have attracted much attention in recent years due to their robustness against defects and disorder. Especially at the interfaces between regions with different topological properties, the emergence of topological edge states enables unidirectional and defect-resistant light transmission. These edge states exhibit the characteristics of unidirectional propagation and high robustness, can effectively suppress backscattering in waveguides, and at the same time have the ability to resist defects and disorder. Therefore, a great deal of effort has been devoted in the field of photonics to realizing these states, especially considering their potential applications in robust optical delay lines, amplifiers, and other devices.
[0004] Topological edge states can also coexist with other topological states, such as topological corner states and bound states in the continuum, providing a rich physical basis for multi-state coexistence, thereby further expanding their application potential. Recent research has achieved multi-band and adjustable topological edge states, making them more adaptable and flexible in different spectral ranges. However, most of the current topological photonic systems operating in the mid-infrared band are still limited to a single band, restricting their diversity and bandwidth operation capabilities. Summary of the Invention
[0005] In view of this, the purpose of the present invention is to provide a mid-infrared range topological resonator for realizing dual-band topological edge states and a design method thereof. By introducing the methods of breaking the rotational symmetry of scatterers and lattice splicing in the honeycomb lattice structure, dual-band operation, high quality factor, and robustness against defects are achieved.
[0006] To achieve the above purpose, the present invention adopts the following technical scheme: A design method for a mid-infrared range topological resonator for realizing dual-band topological edge states, and the specific steps are as follows:
[0007] Step S1: Design valley photonic crystals; the valley photonic crystals are composed of scatterers with a honeycomb lattice arrangement of InAs / GaSb / AlSb as the substrate material. The scatterers are triangular in shape, specifically, the air hole boundaries are treated with an extremely thin metal coating. The lattice period is a, and each scatterer consists of three legs, with its length being: l = y * a, and its width being: w = x * a;
[0008] Step S2: Achieve the first valley photonic crystal VPC1 by rotating the scatterers by θ1, and achieve the second valley photonic crystal VPC2 by rotating the scatterers by θ2;
[0009] Step S3: Splice the first valley photonic crystal VPC1 and the second valley photonic crystal VPC2 to form a topologically protected edge state, calculate its dispersion relation, and obtain its low-frequency working range and high-frequency working range;
[0010] Step S4: Design a supercell structure, achieve a topologically edge state with unidirectional transmission characteristics by splicing two types of valley photonic crystals, and verify its transmission effect in a straight waveguide through simulation;
[0011] Step S5: Design an Ω-shaped waveguide structure based on the edge state. The Ω-shaped waveguide structure has multiple turning angles, and its energy transmission characteristics along the waveguide are demonstrated through simulation;
[0012] Step S6: Based on the above Ω-shaped waveguide structure, construct a dual-band triangular resonator with a side length of L, and its mode distribution is uniform;
[0013] Step S7: Calculate the electric field distribution at the characteristic frequency.
[0014] In a preferred embodiment, the substrate material of the valley photonic crystal is InAs / GaSb / AlSb, with a refractive index of 3.3, and the scatterers use an extremely thin metal coating on the air hole boundaries.
[0015] In a preferred embodiment, the lattice period a of the valley photonic crystal is 985 nm, and the length and width of the scatterers satisfy y = 0.07 and x = 0.46, and the included angle between adjacent legs is 120°.
[0016] In a preferred embodiment, the first valley photonic crystal VPC1 is achieved by rotating the central scatterer by θ1 = 5°, breaking the mirror symmetry and forming a topological band gap.
[0017] In a preferred embodiment, the second valley photonic crystal VPC2 is achieved by rotating the central scatterer by θ2 = -5°, breaking the mirror symmetry and forming a topological band gap.
[0018] In a preferred embodiment, by splicing the first valley photonic crystal VPC1 and the second valley photonic crystal VPC2, topological edge states with a low frequency of approximately 7.5 μm and a high frequency of approximately 3.1 μm are formed.
[0019] In a preferred embodiment, the resonant cavity is composed of a triangular second valley photonic crystal VPC2 embedded in a rectangular first valley photonic crystal VPC1, and a topological resonant cavity based on topological edge states is formed.
[0020] In a preferred embodiment, the side length of the designed triangular resonant cavity is L = 21*a.
[0021] The present invention also provides a mid-infrared range topological resonant cavity for realizing dual-band topological edge states, which is designed by using the above-mentioned design method of a mid-infrared range topological resonant cavity for realizing dual-band topological edge states. The resonant cavity includes a valley photonic crystal based on a scatterer honeycomb lattice structure.
[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention significantly improves the operation bandwidth and flexibility of the resonant cavity, and realizes efficient dual-band operation in the mid-infrared range. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of a valley photonic crystal unit cell and the electric field distribution at the eigenfrequency in a preferred embodiment of the present invention.
[0024] Figure 2 It is a design schematic diagram and the energy band structure of the valley photonic crystal in a preferred embodiment of the present invention.
[0025] Figure 3 It is a supercell structure formed by splicing two types of valley photonic crystals and the corresponding edge state dispersion in a preferred embodiment of the present invention.
[0026] Figure 4 It is the energy transmission characteristic based on the edge state in a preferred embodiment of the present invention, including a straight waveguide and an Ω-shaped waveguide structure and the transmission schematic diagram and the corresponding electric field intensity distribution.
[0027] Figure 5 It is the design of a topologically protected triangular resonant cavity in a preferred embodiment of the present invention, showing the resonant mode distribution and its high-Q factor characteristics.
[0028] Figure 6 It is a schematic diagram of the comparison of the electric field distribution at the characteristic frequencies of no defect, edge defect, and corner defect in a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0030] It should be noted that the following detailed description is illustrative and aims to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.
[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0032] A design method for a mid-infrared range topological resonator to achieve dual-band topological edge states, referring to Figure 1-6 , by introducing the breaking of the rotational symmetry of scatterers in a honeycomb lattice structure, a high-performance resonator is designed. The specific steps are as follows:
[0033] S1: Design a valley photonic crystal. It is composed of scatterers arranged in a honeycomb lattice with a substrate material of InAs / GaSb / AlSb. The shape of the scatterers is triangular, and an extremely thin metal coating treatment is used on the air hole boundary. The lattice period is a. Each scatterer consists of three legs, with its length being: l = y * a and its width being: w = x * a.
[0034] S2: Achieve valley photonic crystal 1 by rotating the scatterers by θ1, and achieve valley photonic crystal 2 by rotating the scatterers by θ2.
[0035] S3: Splice valley photonic crystal 1 and valley photonic crystal 2 to form a topologically protected edge state. Calculate its dispersion relation, and its low-frequency working range and high-frequency working range can be obtained.
[0036] S4: Design a supercell structure, achieve a topologically edge state with unidirectional transmission characteristics by splicing two types of valley photonic crystals, and verify its transmission effect in a straight waveguide through simulation.
[0037] S5: Design an Ω-shaped waveguide structure based on the edge state. This structure has multiple corners. Through simulation, it shows the energy transmission characteristics along the waveguide. Even if the surface passes through multiple bends, it can maintain a stable transmission efficiency, indicating that its transmission mode is topologically protected.
[0038] S6: Based on the above structure, construct a dual-band triangular resonator with a side length of L. Its mode distribution is uniform, and it shows excellent robustness to edge and corner defects.
[0039] S7: Calculate the electric field distribution at the characteristic frequency, indicating that its modal distribution is more uniform and the energy loss is significantly reduced. In addition, by comparing the electric field distributions, it can be found that the topological resonator can still maintain a stable mode distribution in the presence of edge and corner defects, demonstrating excellent topological protection performance.
[0040] In this embodiment, the lattice period a in step S1 is 985 nm, the included angle between adjacent legs is 120°, and the length and width of the scatterer satisfy y = 0.07 and x = 0.46.
[0041] In this embodiment, the rotation angles θ1 and θ2 of VPC1 and VPC2 in step S2 are +5° and -5° respectively.
[0042] In this embodiment, the low-frequency operating frequency band of the resonator in step S3 is from 37.186 THz to 42.632 THz, and the high-frequency operating frequency band is from 94.714 THz to 101.39 THz.
[0043] In this embodiment, the side length L of the triangular resonator in step S6 is 21*a.
[0044] In this embodiment, as Figure 1 shown, the figure shows the schematic diagram of the valley photonic crystal unit cell and the electric field distribution of the formed resonator at the eigenfrequency. By adjusting the rotation angle of the scatterer in the valley photonic crystal unit cell, the rotational symmetry of the crystal can be broken, thereby introducing a topologically protected band gap between the K and K' points. At the eigenfrequency, the electric field energy of the resonator has a uniform distribution.
[0045] In this embodiment, as Figure 2 shown, the figure shows the design schematic diagram of the valley photonic crystal and its band structure. The valley photonic crystal is composed of triangular scatterers arranged in a honeycomb lattice. Each scatterer consists of three legs. The lattice period is 985 nm, and the included angle between adjacent legs is 120°. By rotating the central scatterer by an angle of ±5°, the mirror symmetry of the crystal is broken, thereby forming a topologically protected band gap between the K and K' points. Specifically, the low-frequency band gap ranges from 37.186 THz to 42.632 THz (7.037 μm to 8.068 μm), and the high-frequency band gap ranges from 94.714 THz to 101.39 THz (2.958 μm to 3.167 μm), which is the gray area in the band structure diagram.
[0046] Figure 3It is the supercell structure formed by splicing two valley photonic crystals VPC1 and VPC2 and its edge state dispersion relation in the preferred embodiment of the present invention. As shown in the figure, the supercell is spliced by VPC2 above and VPC1 below, and the energy of the edge state is confined at the junction of the two valley photonic crystals. At the characteristic frequency, the electric field distribution shows that the energy is concentrated in the edge region of the junction, and the arrow indicates the direction of the Poynting vector, showing that the energy flow directions are opposite at the K and K' points. In the band structure, the gray area represents the bulk mode, while the edge state is shown in the form of a curve.
[0047] Figure 4 It is the schematic diagram of energy transmission characteristics based on edge states in the preferred embodiment of the present invention, including the transmission schematic diagrams of straight waveguides and Ω-shaped waveguide structures and the corresponding electric field intensity distributions. As shown in the figure, in different waveguide structures, using left-handed circularly polarized light and right-handed circularly polarized light for excitation, the energy propagates unidirectionally along the waveguide edge. Especially in the Ω-shaped waveguide, even after passing through multiple acute bends, the transmission efficiency remains stable. The corresponding electric field distribution further shows that the energy is concentrated in the boundary region, and the transmission mode is topologically protected and not affected by waveguide structure defects.
[0048] Figure 5 It is the design of a topologically protected triangular resonator in the preferred embodiment of the present invention, showing the resonant mode distribution and its high Q-factor characteristics. The triangular topological resonator is composed of triangular VPC2 embedded in rectangular VPC1, and its side length is 21a. The mode distribution of the resonator is similar to that of a ring resonator mode, with an equally spaced frequency distribution. Among them, the low-frequency quality factor Q value is about 104, while the high-frequency Q value can exceed 109, showing excellent optical performance.
[0049] Figure 6 It is the schematic diagram of the comparison of the electric field distributions at the characteristic frequencies under the conditions of no defect, edge defect, and corner defect in the preferred embodiment of the present invention. Whether in the low-frequency band or the high-frequency band, the topological resonator still maintains a stable electric field distribution in the presence of edge and corner defects, with almost no difference from the distribution without defects, indicating the extremely strong anti-interference ability of the topological cavity. At the same time, the electric field distribution diagram also shows that the energy is evenly distributed along the domain wall in the topological cavity. This uniform distribution enhances the mode stability, reduces the modal interference and local accumulation effect, and at the same time significantly reduces the modal loss and improves the quality factor.
[0050] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.
Claims
1. A method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states, characterized in that: The specific steps are as follows: Step S1: designing a valley photonic crystal; the valley photonic crystal is composed of a scatterer whose base material is an InAs / GaSb / AlSb honeycomb lattice arrangement, the scatterer is triangular in shape, specifically, the air hole boundary is treated with an extremely thin metal coating, the lattice period is a, and each scatterer is composed of three legs, whose length is: l=y*a, and whose width is: w=x*a; Step S2: realizing the first energy valley photonic crystal VPC1 by rotating the scatterer by θ1, and realizing the second energy valley photonic crystal VPC2 by rotating the scatterer by θ2; Step S3: splicing the first valley photonic crystal VPC1 and the second valley photonic crystal VPC2 to form a topologically protected edge state, calculating its dispersion relation, and obtaining its low-frequency working range and high-frequency working range; Step S4: designing a supercell structure, realizing a topological edge state with unidirectional transmission characteristics by splicing two valley photonic crystals, and verifying its transmission effect in a straight waveguide by simulation; Step S5: designing an Ω-shaped waveguide structure based on the edge state, wherein the Ω-shaped waveguide structure has multiple corners, and demonstrating the energy transmission characteristics along the waveguide through simulation; Step S6: Based on the Ω-shaped waveguide structure, a dual-band triangular resonant cavity with a side length of L is constructed, and its mode distribution is uniform; Step S7: Calculate the electric field distribution at the characteristic frequency.
2. The method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states according to claim 1, characterized in that: The base material of the valley photonic crystal is InAs / GaSb / AlSb, with a refractive index of 3.3, and the scatterer is an extremely thin metal coating on the boundary of the air hole.
3. The method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states according to claim 1, characterized in that: The lattice period a of the valley photonic crystal is 985 nm, the length and width of the scatterer satisfy y=0.07, x=0.46, and the angle between two adjacent legs is 120°.
4. The method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states according to claim 1, characterized in that: The first valley photonic crystal VPC1 is realized by rotating the central scatterer by θ1=5°, destroying the mirror symmetry and forming a topological band gap.
5. The method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states according to claim 1, characterized in that: The second valley photonic crystal VPC2 is realized by rotating the central scatterer by θ2 = -5°, destroying the mirror symmetry and forming a topological band gap.
6. The method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states according to claim 1, characterized in that: By splicing the first energy valley photonic crystal VPC1 and the second energy valley photonic crystal VPC2, topological edge states with a low frequency of about 7.5μm and a high frequency of about 3.1μm are formed.
7. The method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states according to claim 1, characterized in that: The resonant cavity is composed of a triangular second energy valley photonic crystal VPC2 embedded in a rectangular first energy valley photonic crystal VPC1, and forms a topological resonant cavity based on a topological edge state.
8. The method for designing a mid-infrared topological resonant cavity for realizing dual-band topological edge states according to claim 1, characterized in that: The side length of the designed triangular resonant cavity is L=21*a.
9. A mid-infrared range topological resonant cavity realizing dual-band topological edge states, characterized in that: The resonant cavity is designed using the mid-infrared range topological resonant cavity design method for realizing dual-band topological edge states as described in any one of claims 1 to 8, and the resonant cavity includes a valley photonic crystal based on a scatterer honeycomb lattice structure.