Non-Hermite metasurface for short-interval wavelength division multiplexing and optical system

Abstract

The invention provides a non-Hermite metasurface for short-interval wavelength division multiplexing and an optical system, the metasurface is provided with a plurality of super unit cells, each super unit cell is sequentially provided with a first metal layer, an insulating layer and a second metal layer, and the overlook angle of each super unit cell is a cube; the second metal layer is provided with a first metal body and a second metal body, the first metal body and the second metal body are both cuboids, the first metal body and the second metal body are arranged on the two sides of the gravity center point of the overlooking plane of the super-unit cell respectively on the overlooking plane of the super-unit cell, and the second metal body is arranged on the two sides of the gravity center point of the overlooking plane of the super-unit cell respectively on the overlooking plane of the super-unit cell. And a first inclination angle is formed between the straight line of the length direction of the first metal body and the length direction of the first metal body. According to the scheme, the characteristic that the non-Hermite singular point (EP) moves along with the wavelength in the parameter space of the gold double-rod type unit structure is utilized, and independent phase regulation and control are achieved respectively.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a non-Hermitian metasurface and an optical system for short-interval wavelength division multiplexing. Background Art

[0002] In recent years, the multifunctional properties of metasurfaces have become a hot topic in metasurface research, with their ability to simultaneously realize multiple optical functions attracting widespread attention. Compared with traditional single-function metasurfaces, multifunctional metasurfaces not only more efficiently utilize the spatial resources of optical devices, but also significantly improve the integration and functionality of the system.

[0003] Common multifunctional metasurfaces include polarization, wavelength, and incident angle multiplexing metasurfaces. Wavelength multiplexing treats each wavelength as an independent channel, simultaneously transmitting or processing multiple different information, and each channel is independent of each other. This method can be used for parallel data transmission, multi-channel optical communication, and improving information transmission and processing efficiency and information storage density. This method has been proven to effectively enhance the performance of communication and encryption systems, and its performance can be further improved by increasing the number of multiplexed wavelengths (reducing the wavelength spacing) within the system's operating band. Traditional wavelength multiplexing methods, including the use of neural networks and algorithm-assisted design, combined with polarization multiplexing and spatial partitioning methods to independently control multiple wavelengths, typically multiplex wavelengths greater than 50 nm apart. This is because the optical properties of current metasurface materials lack the required diversity across multiple wavelengths. For example, in specific communication bands and imaging bands, commonly used materials such as amorphous silicon and titanium dioxide cannot provide differentiated optical parameters such as refractive index and reflectivity. In a multi-wavelength multiplexing system, light beams of different wavelengths need to be precisely and effectively controlled. However, the limitations of these materials make it impossible for metasurfaces to achieve this goal, which in turn hinders the functional diversification of metasurfaces in wavelength multiplexing research. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a non-Hermitian metasurface and an optical system for short-interval wavelength division multiplexing to eliminate or improve one or more defects in the prior art.

[0005] One aspect of the present invention provides a non-Hermitian metasurface for short-interval wavelength division multiplexing, wherein the metasurface is provided with a plurality of supercells, each supercell being sequentially provided with a first metal layer, an insulating layer, and a second metal layer, and the supercell is a cube when viewed from above;

[0006] The second metal layer is provided with a first metal body and a second metal body, and the first metal body and the second metal body are both rectangular prisms. In the top-view plane of the supercell, the first metal body and the second metal body are respectively arranged on both sides of the center of gravity of the top-view plane of the supercell. In the top-view plane of the supercell, a first inclination angle is set between the straight line where the length direction of the first metal body is located and the length direction of the first metal body.

[0007] This approach leverages the wavelength-dependent shift of non-Hermitian singular points (EPs) in the parameter space of gold double-rod unit structures to realize a wavelength-reuse metasurface with short wavelength intervals. By selecting the geometric parameters of the metasurface's unit structures around the EPs in the parameter space and rotating the structure using a geometric phase mechanism, this approach achieves independent phase control at wavelengths where the path formed by the selected structural parameters surrounds the EPs, as well as at wavelengths where the path does not contain the EPs.

[0008] In some embodiments of the present invention, the metal material used for the first metal layer and the second metal layer is gold, and the material of the insulating layer is silicon dioxide.

[0009] In some embodiments of the present invention, the length, width, and height of the first metal body of each supercell of the metasurface are the same, and the height of the second metal body is the same as that of the first metal body.

[0010] In some embodiments of the present invention, the length of the first metal body is in the range of 350 to 400 nm, the width of the first metal body is in the range of 80 to 120 nm, and the height of the first metal body is 120 nm.

[0011] In some embodiments of the present invention, in a top-view plane of the supercell, the distances between the center of gravity of the first metal body and the second metal body and the center of gravity of the top-view plane of the supercell are both first distances.

[0012] In some embodiments of the present invention, the first distance is 180-220 nm.

[0013] In some embodiments of the present invention, in a top-view plane of the supercell, the center of gravity of the first metal body and the second metal body and a line connecting the center of gravity of the top-view plane of the supercell are in the same straight line.

[0014] In some embodiments of the present invention, in the top-view plane of the supercell, a second inclination angle exists between a line connecting the center of gravity of the first metal body and the second metal body and the center of gravity of the top-view plane of the supercell and an edge line of the top-view plane of the supercell.

[0015] In some embodiments of the present invention, the length of the second metal body is in the range of 300 to 500 nm, and the width of the second metal body is in the range of 100 to 300 nm.

[0016] In some embodiments of the present invention, a first target wavelength and a second target wavelength are obtained to obtain corresponding first phase diagrams, a corresponding first phase is determined based on the position of the supercell on the metasurface compared with a preset first phase diagram, and a second tilt angle of the supercell is calculated based on the first phase; a corresponding second phase is determined based on the position of the supercell on the metasurface compared with a preset second phase diagram; a phase shift value at the EP wavelength is calculated based on the first phase and the second phase, and the length and width of the second metal body in the supercell are determined based on the phase shift value at the EP wavelength.

[0017] In some embodiments of the present invention, in the steps of calculating the second tilt angle of the supercell based on the first phase and calculating the phase shift value at the EP wavelength based on the first phase and the second phase, the second tilt angle and the phase shift value at the EP wavelength are calculated according to the following formula:

[0018]

[0019] Where θ represents the second inclination angle, represents the first phase, represents the phase shift value at the EP wavelength, Indicates the second phase.

[0020] Another aspect of the present invention provides an optical system, wherein the optical system adopts the above-mentioned non-Hermitian metasurface for short-spacing wavelength division multiplexing.

[0021] Additional advantages, objects, and features of the present invention will be described in part in the following description and will become apparent to those skilled in the art after studying the following or may be learned by practice of the present invention. The objects and other advantages of the present invention may be particularly pointed out and attained in the description and drawings.

[0022] Those skilled in the art will understand that the purposes and advantages that can be achieved by the present invention are not limited to the above specific descriptions, and the above and other purposes that can be achieved by the present invention will be more clearly understood based on the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute a limitation of the present invention.

[0024] Figure 1 Schematic diagram of the structure of the non-Hermitian metasurface and optical system used for short-interval wavelength division multiplexing in this scheme;

[0025] Figure 2 The reflection spectra of each polarization channel of the metasurface under the parameters of L2 = 377nm and W2 = 230nm;

[0026] Figure 3 Schematic diagram of the changes in eigenvalues ​​and eigenvectors of the metasurface under the parameters L2 = 377nm and W2 = 230nm;

[0027] Figure 4 Schematic diagram of the changes in the eigenvalues ​​of each structure;

[0028] Figure 5 Schematic diagram of the phase response of the supercell at different wavelengths;

[0029] Figure 6 Schematic diagram of the phase correspondence of the supercell;

[0030] Figure 7 Schematic diagram of the vortex beam simulation results of the metasurface;

[0031] Figure 8 Schematic diagram of the hologram simulation results of the metasurface;

[0032] Figure 9 When the first wavelength is 1530 nm and the second wavelength is 1568 nm, the first phase diagram corresponding to 1530 nm;

[0033] Figure 10 When the first wavelength is 1530 nm and the second wavelength is 1568 nm, the second phase diagram corresponding to 1568 nm;

[0034] Figure 11 is the first phase diagram corresponding to 1530nm when the first wavelength is 1550nm and the second wavelength is 1568nm;

[0035] Figure 12 When the first wavelength is 1550 nm and the second wavelength is 1568 nm, the second phase diagram corresponding to 1568 nm. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0037] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show structures and / or processing steps closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0038] Another area of ​​metasurface research is the study of non-Hermitian singular points (EPs), which are singular points in a non-Hermitian system where two eigenvalues ​​and their corresponding eigenvectors merge. Metasurfaces provide an ultra-thin multifunctional platform for non-Hermitian optical systems, significantly enhancing the ability to manipulate electromagnetic waves. Research on EPs has revealed various physical phenomena and promoted the development of applications such as unidirectional propagation, polarization control, and perfect absorption. In addition, non-Hermitian metasurfaces provide new ideas for multifunctional metasurfaces, which can achieve independent phase manipulation of orthogonal polarization channels and full-space beam inputs. However, current existing technologies have not yet used non-Hermitian metasurfaces to perform independent phase control between two short-interval wavelengths. Based on the above research background, this scheme uses the characteristic that EPs in non-Hermitian metasurfaces move with wavelength in parameter space to propose a metasurface for wavelength multiplexing with a multiplexing interval of less than 30nm (specifically 28nm and 18nm).

[0039] like Figure 1 As shown, the present invention proposes a non-Hermitian metasurface and an optical system for short-interval wavelength division multiplexing, wherein the metasurface is provided with a plurality of supercells, each of which is sequentially provided with a first metal layer, an insulating layer, and a second metal layer, and the supercell is a cube when viewed from above;

[0040] The second metal layer is provided with a first metal body and a second metal body, and the first metal body and the second metal body are both rectangular prisms. In the top-view plane of the supercell, the first metal body and the second metal body are respectively arranged on both sides of the center of gravity of the top-view plane of the supercell. In the top-view plane of the supercell, a first inclination angle is set between the straight line where the length direction of the first metal body is located and the length direction of the first metal body.

[0041] In some embodiments of the present invention, the thickness of the first metal layer is in the range of 200 to 400 nm, specifically 300 nm, and the thickness of the insulating layer is in the range of 100 to 150 nm, specifically 120 nm.

[0042] Specifically, the first inclination angle θ0=45°.

[0043] This approach leverages the wavelength-dependent shift of non-Hermitian singular points (EPs) in the parameter space of gold double-rod unit structures to realize a wavelength-reuse metasurface with short wavelength intervals. By selecting the geometric parameters of the metasurface's unit structures around the EPs in the parameter space and rotating the structure using a geometric phase mechanism, this approach achieves independent phase control at wavelengths where the path formed by the selected structural parameters surrounds the EPs, as well as at wavelengths where the path does not contain the EPs.

[0044] In some embodiments of the present invention, the metal material used for the first metal layer and the second metal layer is gold, and the material of the insulating layer is silicon dioxide.

[0045] In some embodiments of the present invention, the length, width, and height of the first metal body of each supercell of the metasurface are the same, and the height of the second metal body is the same as that of the first metal body.

[0046] In some embodiments of the present invention, the length of the first metal body is in the range of 350 to 400 nm, the width of the first metal body is in the range of 80 to 120 nm, and the height of the first metal body is 120 nm.

[0047] In some embodiments of the present invention, the length L1 of the first metal body is 370 nm and the width W1 is 100 nm.

[0048] In some embodiments of the present invention, in a top-view plane of the supercell, the distances between the center of gravity of the first metal body and the second metal body and the center of gravity of the top-view plane of the supercell are both first distances.

[0049] In some embodiments of the present invention, the first distance is 180-220 nm.

[0050] In some embodiments of the present invention, the first distance is 200 nm.

[0051] In some embodiments of the present invention, in a top-view plane of the supercell, the center of gravity of the first metal body and the second metal body and a line connecting the center of gravity of the top-view plane of the supercell are in the same straight line.

[0052] In some embodiments of the present invention, in the top-view plane of the supercell, a second inclination angle exists between a line connecting the center of gravity of the first metal body and the second metal body and the center of gravity of the top-view plane of the supercell and an edge line of the top-view plane of the supercell.

[0053] In some embodiments of the present invention, the length of the second metal body is in the range of 300 to 500 nm, and the width of the second metal body is in the range of 100 to 300 nm.

[0054] like Figure 9 、 10As shown in Figures 11 and 12, in some embodiments of the present invention, a first target wavelength and a second target wavelength are obtained to obtain a corresponding first phase diagram and a second phase diagram, and a corresponding first phase is determined based on the position of the supercell on the metasurface and the preset first phase diagram, and a second tilt angle of the supercell is calculated based on the first phase; a corresponding second phase is determined based on the position of the supercell on the metasurface and the preset second phase diagram; a phase shift value at the EP wavelength is calculated based on the first phase and the second phase, and the length and width of the second metal body in the supercell are determined based on the phase shift value at the EP wavelength.

[0055] Compare the position of the supercell in the first phase diagram and the second phase diagram, and determine the corresponding first phase and second phase based on the gray value of the position and the comparison bar on the right side of the comparison diagram. Calculate the phase shift value at the EP wavelength based on the following formula. Figure 6 The value of the vertical axis in (a) is based on the corresponding curve of 1568nm, and the corresponding supercells in the supercells numbered 1, 2, 3 and 4 are determined. Specifically, if the phase shift value at the EP wavelength is calculated to be 1.5, the similar supercells are 1 and 2, respectively. Among them, the phase shift value at the EP wavelength corresponding to supercell 1 is closer to 1.5, and the corresponding supercell is the supercell numbered 1.

[0056] In some embodiments of the present invention, in the steps of calculating the second tilt angle of the supercell based on the first phase and calculating the phase shift value at the EP wavelength based on the first phase and the second phase, the second tilt angle and the phase shift value at the EP wavelength are calculated according to the following formula:

[0057]

[0058] Where θ represents the second inclination angle, represents the first phase, represents the phase shift value at the EP wavelength, Indicates the second phase.

[0059] In the specific implementation process, the length of the second metal ladder of the supercell is L2 and the width is W2. When L2 = 377nm and W2 = 230nm, the reflectivity of the unit structure under left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) light beams is as follows: Figure 2 As shown. At 1568nm wavelength, RCP to LCP conversion (r lr ), the reflection coefficient from left-hand circular polarization to right-hand circular polarization drops sharply to almost zero. This asymmetric conversion is a clear sign of a non-Hermitian system. At the same time, at a wavelength of 1568nm, the real and imaginary parts of the eigenvalues ​​are merged, such as Figure 3 As shown in (a), Figure 3(a) is a schematic diagram of the eigenvalue changes of the metasurface under the parameters L2 = 377nm and W2 = 230nm. In the figure, EV1 and EV2 are the two eigenvalues ​​of the Jones matrix, confirming the spectral singularity observed in the reflection coefficient. This merger not only means the degeneracy of the eigenvalues, but also the degeneracy of the eigenstates, confirming the existence of a chiral singularity point where the right-handed circular polarization state becomes the only eigenstate, as shown in Figure 1. Figure 3 (b) and Figure 4 As shown in (a, b), Figure 3 (b) is a schematic diagram of the change of eigenvectors represented by the Poincare sphere. S1, S2 and S3 are the three coordinate axes of the Poincare sphere, and the red star represents the position of the EP point. Figure 4 (a) and Figure 4 (b) Schematic diagram of the changes in the real and imaginary parts of the eigenvalues. When the reflection matrix of each position is calculated in the geometric parameter space, the self-intersecting Riemann surface formed by its eigenvalues ​​further confirms this degeneracy.

[0060] like Figure 5 As shown, Figure 5 The white dotted circle represents a schematic diagram of the path formed by the selected unit structure; the red star represents the position of the EP point; and the black dotted line represents the path of EP movement. Since the position of EP in R is related to the wavelength, and the direction of its movement with wavelength roughly coincides with the W2 coordinate axis in this case. Therefore, when selecting the unit structure around EP, we can consciously limit the range of change of W2, so that when the wavelength changes, the EP quickly escapes from the area surrounded by the path formed by the unit structure. In this case, the wavelength λ1 where the path does not surround the EP is not obvious, and the phase change of the unit structure is not obvious at the wavelength λ2 where the path surrounds the EP. However, due to the properties of the topological phase, the unit structure has a phase accumulation of 2π. Since EP occurs in the cross-polarization channel (LCP to RCP), closely spaced wavelength multiplexing can be achieved by applying a geometric phase.

[0061] Figure 6 (a) is the phase at each wavelength when the unit structure does not rotate; Figure 6 (b) is the phase at 1530 nm after the unit structure is rotated; Figure 6 (c) is the phase at 1568nm after the unit structure is rotated; Figure 6As shown in (a), the unit structure along the selected path exhibits a uniform phase distribution at 1530nm, becomes disordered at 1550nm, and finally achieves complete 2π phase coverage at 1568nm, with a continuous interval of π / 4. The geometric parameters of the unit structure are shown in Table 1. Table 1 is a schematic diagram of the geometric parameters of the supercells of the four structures when the first target wavelength is 1530nm and the second target wavelength is 1568nm; Table 2 is a schematic diagram of the geometric parameters of the supercells of the four structures when the first target wavelength is 1550nm and the second target wavelength is 1568nm. By increasing the rotation angle of the unit structure, the geometric phase can be introduced to impose an additional phase shift, which is applicable to each structure. The phase results at two wavelengths are shown in Table 1. Figure 6 (b, c) In order to construct a metasurface with different phase modulations at different wavelengths, the phase modulation at λ1 is determined only by the geometric phase The phase modulation at λ2 contains both geometric phase and topological phase: in represents the phase shift at the EP wavelength of the metaatom. Therefore, the rotation angle of the unit structure forming the metasurface and its phase value at the EP wavelength when it is not rotated are It can be expressed as:

[0062]

[0063] Table 1

[0064] Unit number <![CDATA[L2(nm)]]> <![CDATA[W2(nm)]]> 1 360 200 2 370 290 3 390 290 4 390 160

[0065] To verify the feasibility of this scheme, a practical demonstration of its versatility was conducted. For this purpose, a metasurface was designed that can generate vortex beams with topological charges l = 1 and l = 2 at two wavelengths (1530nm and 1568nm), respectively. Figure 7 (a) is the intensity distribution of the output light field at 1530nm; Figure 7 (b) is the phase distribution of the output light field at 1530nm; Figure 7 (c) is the intensity distribution of the output light field at 1568nm; Figure 7 (d) is the phase distribution of the output light field at 1568nm, and the intensity and phase diagram at 1530nm are shown in Figure 2. Figure 7 (a) and Figure 7 (b) It can be clearly observed that the intensity at the center of the beam caused by the helicity of the phase disappears, indicating that the topological charge of the vortex beam is l = 1. Then, this scheme shifts the detected wavelength to 1568nm while maintaining the same observation range. For the same metasurface, this scheme can observe a vortex beam with l = 2, whose annular intensity has a larger radius and a larger area with zero intensity at the center of the beam, as shown in Figure 7(c). In addition, two phase singularities appear in the phase distribution as Figure 7 (d) shows that its topological charge becomes 2. These results strongly prove that the metasurface can independently control the light field manipulation properties at 1530nm and 1568nm, realizing wavelength multiplexing and decoupled vortex beam generation.

[0066] Selecting different metasurface units allows for different wavelength reuse intervals. Here, this proposal selects a set of metasurface unit structural parameters, as shown in Table 2. This set of geometric parameters exhibits minimal variation in W2 and significant variation in L2. The path constructed with this set of parameters also contains an EP at 1568nm, but this EP rapidly shifts with wavelength, resulting in a loss of topological protection. Therefore, this metasurface can provide a shorter wavelength reuse interval. Figure 8 (a) is the intensity distribution of the output light field at 1550nm; Figure 8 (b) is the phase distribution of the output light field at 1568nm, as shown in Figure 8 As shown in (a), this scheme selects letters “E” and “P” as target holograms and places them at different positions. Figure 8 The simulation results (b) show that the holograms at wavelengths of 1550 nm and 1568 nm match the target image well. These results demonstrate the ability of the non-Hermitian metasurface to independently control the phase of two closely spaced wavelength channels.

[0067] Table 2

[0068] Unit number <![CDATA[L2(nm)]]> <![CDATA[W2(nm)]]> 1 365 225 2 350 230 3 395 230 4 420 225

[0069] In summary, this scheme strategically selects the parameters of the metasurface unit structure in the metasurface parameter space with singular points to achieve short-interval wavelength multiplexing, which is expected to be widely used in information encryption, optical communications, laser processing and other fields.

[0070] Another aspect of the present invention provides an optical system, wherein the optical system adopts the above-mentioned non-Hermitian metasurface for short-spacing wavelength division multiplexing.

[0071] It should be understood by those skilled in the art that the various exemplary components, systems and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software or a combination of the two. Whether it is specifically performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present invention are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link via a data signal carried in a carrier.

[0072] It should be understood that the present invention is not limited to the specific configurations and processes described above and illustrated in the figures. For the sake of brevity, a detailed description of known methods is omitted. In the above embodiments, several specific steps are described and illustrated as examples. However, the method of the present invention is not limited to the specific steps described and illustrated. Those skilled in the art may make various changes, modifications, and additions, or change the order of the steps after understanding the spirit of the present invention.

[0073] In the present invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or replace features of other embodiments.

[0074] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations to the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A non-Hermitian metasurface for short-interval wavelength division multiplexing, characterized in that: The metasurface is provided with a plurality of supercells, each of which is sequentially provided with a first metal layer, an insulating layer, and a second metal layer, and the supercell is a cube when viewed from above; The second metal layer is provided with a first metal body and a second metal body, and the first metal body and the second metal body are both rectangular prisms. In the top-view plane of the supercell, the first metal body and the second metal body are respectively arranged on both sides of the center of gravity of the top-view plane of the supercell. In the top-view plane of the supercell, a first inclination angle is set between the straight line where the length direction of the first metal body is located and the length direction of the first metal body.

2. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 1, characterized in that: The length, width and height of the first metal body of each supercell on the metasurface are the same, and the height of the second metal body is the same as that of the first metal body.

3. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 2, characterized in that: The length of the first metal body is in the range of 350 to 400 nm, the width of the first metal body is in the range of 80 to 120 nm, and the height of the first metal body is 120 nm.

4. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 1, wherein: In a top-view plane of the supercell, the distances between the center of gravity of the first metal body and the second metal body and the center of gravity of the top-view plane of the supercell are both first distances.

5. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 3, characterized in that: In a top-view plane of the supercell, the center of gravity of the first metal body and the second metal body and a line connecting the center of gravity of the top-view plane of the supercell are in the same straight line.

6. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 5, characterized in that: On the top-view plane of the supercell, a second inclination angle exists between a line connecting the center of gravity of the first metal body and the second metal body and the center of gravity of the top-view plane of the supercell and an edge line of the top-view plane of the supercell.

7. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 2, characterized in that: The length of the second metal body is in the range of 300 to 500 nm, and the width of the second metal body is in the range of 100 to 300 nm.

8. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 6, characterized in that: Obtain the first target wavelength and the second target wavelength and obtain the corresponding first phase diagram and second phase diagram, determine the corresponding first phase based on the position of the supercell on the metasurface and the preset first phase diagram, and calculate the second tilt angle of the supercell based on the first phase; determine the corresponding second phase based on the position of the supercell on the metasurface and the preset second phase diagram; calculate the phase shift value at the EP wavelength based on the first phase and the second phase, and determine the length and width of the second metal body in the supercell based on the phase shift value at the EP wavelength.

9. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 8, characterized in that: In the steps of calculating the second tilt angle of the supercell based on the first phase and calculating the phase shift value at the EP wavelength based on the first phase and the second phase, the second tilt angle and the phase shift value at the EP wavelength are calculated according to the following formula: Where θ represents the second inclination angle, represents the first phase, represents the phase shift value at the EP wavelength, Indicates the second phase.

10. An optical system, characterized in that: The optical system adopts the non-Hermitian metasurface for short-interval wavelength division multiplexing according to any one of claims 1 to 9.

Images