A non-hermitian metasurface for short-interval wavelength division multiplexing and optical system

Abstract

This invention provides a non-Hermitian metasurface and optical system for short-interval wavelength division multiplexing. The metasurface is provided with multiple supercells, each supercell sequentially having a first metal layer, an insulating layer, and a second metal layer. The top view of the supercell is cubic. The second metal layer has a first metal body and a second metal body, both of which are cuboids. In the top view of the supercell, the first and second metal bodies are respectively located on either side of the centroid of the top view of the supercell. In the top view of the supercell, a first tilt angle is set between the line containing the length direction of the first metal body and the length direction of the first metal body. This solution utilizes the characteristic that the non-Hermitian exceptional point (EP) in the parameter space of the gold double-rod unit structure shifts with wavelength to achieve independent phase modulation.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more particularly to a non-Hermitian metasurface and optical system for short-interval wavelength division multiplexing. Background Technology

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

[0003] Common multifunctional metasurfaces include those that reuse polarization, wavelength, and incident angle. Wavelength multiplexing treats each wavelength as an independent channel, simultaneously transmitting or processing multiple different pieces of information. These channels are independent of each other, enabling parallel data transmission, multi-channel optical communication, and improved information transmission and processing efficiency and storage density. This method has proven effective in enhancing the performance of communication and encryption systems, and its performance can be further improved by increasing the number of reusable wavelengths within the system's operating band (reducing wavelength spacing). Traditional wavelength multiplexing methods, including those using neural networks and algorithms for design, combined with polarization multiplexing and spatial partitioning, allow for independent control of multiple wavelengths. The wavelengths used in these methods are typically more than 50 nm apart. This is because current metasurface materials lack the necessary diversity in optical properties across multiple wavelength ranges. For example, in specific communication 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 multi-wavelength multiplexing systems, precise and effective control of beams of different wavelengths is required. However, the limitations of these materials prevent metasurfaces from achieving this goal, thus hindering 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 optical system for short-interval wavelength division multiplexing, in order to eliminate or improve one or more defects existing in the prior art.

[0005] One aspect of the present invention provides a non-Hermitian metasurface for short-interval wavelength division multiplexing, the metasurface being provided with a plurality of supercells, each supercell being provided with a first metal layer, an insulating layer and a second metal layer in sequence, the supercells being cubic in plan view;

[0006] The second metal layer is provided with a first metal body and a second metal body, both of which are cuboids. In the top view of the supercell, the first metal body and the second metal body are respectively disposed on both sides of the centroid of the top view of the supercell. In the top view of the supercell, a first tilt angle is provided between the straight line containing the length direction of the first metal body and the length direction of the first metal body.

[0007] Using the above scheme, this approach leverages the wavelength-dependent property of non-Hermitian exceptional points (EPs) in the parameter space of a gold double-rod unit structure to achieve a wavelength-reusing metasurface with short wavelength intervals. By selecting the geometric parameters of the unit structure constituting the metasurface around the EPs in the parameter space and combining this with a geometric phase mechanism to rotate the structure as a whole, this scheme achieves independent phase modulation at the wavelengths around the EPs formed by the selected structural parameters, and at wavelengths not containing the EPs.

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

[0009] In some embodiments of the present invention, 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 the height 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 350-400 nm, the width of the first metal body is in the range of 80-120 nm, and the height of the first metal body is 120 nm.

[0011] In some embodiments of the present invention, in the top view plane of the supercell, the distance between the centroids of the first metal body and the second metal body and the centroid of the top view plane of the supercell is a first distance.

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

[0013] In some embodiments of the present invention, in the top view plane of the supercell, the centroids of the first metal body and the second metal body are aligned with the centroid of the top view plane of the supercell.

[0014] In some embodiments of the present invention, in the top view plane of the supercell, there is a second tilt angle between the line connecting the centroid of the first metal body and the centroid of the top view plane of the supercell and the 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 ranges from 300 to 500 nm, and the width of the second metal body ranges from 100 to 300 nm.

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

[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 formulas:

[0018]

[0019] Where θ represents the second tilt angle. Indicates the first phase. This represents the phase shift value at the EP wavelength. This indicates the second phase.

[0020] Another aspect of the present invention provides an optical system employing the aforementioned non-Hermitian metasurface for short-interval wavelength division multiplexing.

[0021] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the text, or may be learned by practice of the invention. The objects and other advantages of the invention will become apparent from the description and the accompanying drawings.

[0022] Those skilled in the art will understand that the objectives and advantages achievable with the present invention are not limited to those specifically described above, and that the above and other objectives achievable with the present invention will become clearer from the following detailed description. Attached Figure Description

[0023] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, are not intended to limit the scope of the invention.

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

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

[0026] Figure 3 A schematic diagram showing the changes in eigenvalues ​​and eigenvectors of a metasurface under parameters L2 = 377 nm and W2 = 230 nm.

[0027] Figure 4 A schematic diagram showing the changes in the eigenvalues ​​of each structure;

[0028] Figure 5 This is a schematic diagram of the phase response of a supercell at different wavelengths.

[0029] Figure 6 This is a schematic diagram of the phase correspondence of a supercell;

[0030] Figure 7 A schematic diagram of the simulation results of vortex beams on metasurfaces;

[0031] Figure 8 This is a schematic diagram of the holographic simulation results of the metasurface;

[0032] Figure 9 The first phase diagram corresponding to 1530nm is given when the first wavelength is 1530nm and the second wavelength is 1568nm.

[0033] Figure 10 The second phase diagram corresponding to 1568nm is given when the first wavelength is 1530nm and the second wavelength is 1568nm.

[0034] Figure 11 The first phase diagram is shown at 1530nm when the first wavelength is 1550nm and the second wavelength is 1568nm.

[0035] Figure 12 This is the second phase diagram corresponding to 1568nm when the first wavelength is 1550nm and the second wavelength is 1568nm. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

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

[0038] Another area of ​​metasurface research is the study of non-Hermitian exceptional points (EPs), which are singularities in non-Hermitian systems where their two eigenvalues ​​and corresponding eigenvectors merge. Metasurfaces provide an ultrathin, multifunctional platform for non-Hermitian optical systems, significantly enhancing the ability to manipulate electromagnetic waves. Research on EPs has revealed various physical phenomena and advanced applications such as unidirectional propagation, polarization control, and perfect absorption. Furthermore, non-Hermitian metasurfaces offer new insights into multifunctional metasurfaces, enabling independent phase manipulation of orthogonal polarization channels and beam inputs across the entire space. However, current techniques do not utilize non-Hermitian metasurfaces for independent phase modulation between two short-interval wavelengths. Based on this research background, this proposal utilizes the characteristic of EPs shifting with wavelength in parameter space within non-Hermitian metasurfaces to propose a wavelength-multiplexing metasurface with multiplexing intervals less than 30 nm (specifically 28 nm and 18 nm).

[0039] like Figure 1 As shown, the present invention proposes a non-Hermitian metasurface and optical system for short-interval wavelength division multiplexing. The metasurface is provided with multiple supercells, and each supercell is sequentially provided with a first metal layer, an insulating layer and a second metal layer. The top view of the supercell is a cube.

[0040] The second metal layer is provided with a first metal body and a second metal body, both of which are cuboids. In the top view of the supercell, the first metal body and the second metal body are respectively disposed on both sides of the centroid of the top view of the supercell. In the top view of the supercell, a first tilt angle is provided between the straight line containing the length direction of the first metal body 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 200-400 nm, specifically 300 nm, and the thickness of the insulating layer is in the range of 100-150 nm, specifically 120 nm.

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

[0043] Using the above scheme, this approach leverages the wavelength-dependent property of non-Hermitian exceptional points (EPs) in the parameter space of a gold double-rod unit structure to achieve a wavelength-reusing metasurface with short wavelength intervals. By selecting the geometric parameters of the unit structure constituting the metasurface around the EPs in the parameter space and combining this with a geometric phase mechanism to rotate the structure as a whole, this scheme achieves independent phase modulation at the wavelengths around the EPs formed by the selected structural parameters, and at wavelengths not containing the EPs.

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

[0045] In some embodiments of the present invention, 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 the height 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 350-400 nm, the width of the first metal body is in the range of 80-120 nm, and the height of the first metal body is 120 nm.

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

[0048] In some embodiments of the present invention, in the top view plane of the supercell, the distance between the centroids of the first metal body and the second metal body and the centroid of the top view plane of the supercell is a first distance.

[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 the top view plane of the supercell, the centroids of the first metal body and the second metal body are aligned with the centroid of the top view plane of the supercell.

[0052] In some embodiments of the present invention, in the top view plane of the supercell, there is a second tilt angle between the line connecting the centroid of the first metal body and the centroid of the top view plane of the supercell and the 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 ranges from 300 to 500 nm, and the width of the second metal body ranges from 100 to 300 nm.

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

[0055] By comparing the positions of the supercell in the first and second phase maps, and based on the grayscale values ​​at those positions, the corresponding first and second phases are determined using the contrast bars on the right side of the maps. The phase shift value at the EP wavelength is then calculated using the following formula. Figure 6 The value of the vertical axis in (a) is used to determine the supercells corresponding to supercells numbered 1, 2, 3 and 4 based on the corresponding curve at 1568nm. Specifically, if the phase shift value at the EP wavelength is calculated to be 1.5, then the closest supercells are 1 and 2, and the phase shift value at the EP wavelength corresponding to supercell 1 is closer to 1.5, so the corresponding supercell is supercell number 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 formulas:

[0057]

[0058] Where θ represents the second tilt angle. Indicates the first phase. This represents the phase shift value at the EP wavelength. This indicates the second phase.

[0059] In the specific implementation process, let the length of the second metallic ladder of the supercell be L2 and the width be W2. When L2 = 377 nm and W2 = 230 nm, the reflectivity of the unit cell structure under incident left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) beams is as follows: Figure 2 As shown. At a wavelength of 1568 nm, the RCP to LCP conversion (r lr The reflection coefficient drops sharply to almost zero when transitioning from left-handed to right-handed circular polarization; this asymmetric conversion is a hallmark of non-Hermitian systems. Simultaneously, at a wavelength of 1568 nm, the real and imaginary parts of the eigenvalues ​​merge, as shown... Figure 3 As shown in (a). Figure 3(a) is a schematic diagram showing the eigenvalue changes of the metasurface under the parameters L2 = 377 nm and W2 = 230 nm. EV1 and EV2 are two eigenvalues ​​of the Jones matrix, confirming the spectral singularity observed in the reflection coefficient. This merging not only implies eigenvalue degeneracy but also eigenstate degeneracy, confirming the existence of a chiral singularity where the right-handed circularly polarized state becomes the only eigenstate. Figure 3 (b) and Figure 4 As shown in (a,b). Figure 3 (b) is a schematic diagram of the eigenvector changes represented by a Poincaré sphere, where S1, S2, and S3 are the three coordinate axes of the Poincaré sphere, and the red star indicates the position of point EP. Figure 4 (a) and Figure 4 (b) shows the changes in the real and imaginary parts of the eigenvalues, respectively. When the reflection matrix at 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 dashed circle represents the path formed by the selected unit structure; the red star indicates the position of point EP; the black dashed line represents the path of EP's movement. Since the position of EP in R is wavelength-dependent, and its direction of movement with wavelength roughly coincides with the W2 coordinate axis in this case, we can consciously limit the range of W2 when selecting unit structures around EP. This allows EP to quickly move out of the area enclosed by the path formed by the unit structure when the wavelength changes. In this case, the phase change of the unit structure is not significant at wavelength λ1 where the path does not enclose EP, but due to the properties of topological phase, the unit structure has a 2π phase accumulation at wavelength λ2 where the path encloses EP. Since EP occurs in the cross-polarization channel (LCP to RCP), closely spaced wavelength multiplexing can be achieved by applying geometric phase.

[0061] Figure 6 (a) is the phase of the unit structure at each wavelength when it is not rotating; Figure 6 (b) is the phase at 1530 nm after the unit structure is rotated; Figure 6 (c) represents the phase at 1568 nm after the unit structure is rotated; as shown in the image. Figure 6As shown in (a), the unit cell structure along the selected path exhibits a uniform phase distribution at 1530 nm, becomes disordered at 1550 nm, and finally achieves complete 2π phase coverage at 1568 nm with continuous intervals of π / 4. The geometric parameters of the unit cell 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 1530 nm and the second target wavelength is 1568 nm; Table 2 is a schematic diagram of the geometric parameters of the supercells of the four structures when the first target wavelength is 1550 nm and the second target wavelength is 1568 nm. By increasing the rotation angle of the unit cell structure, an additional phase shift can be introduced by the geometric phase, which is applicable to each structure. The phase results at the two wavelengths are as follows: Figure 6 As shown in (b, c). To construct metasurfaces with different phase modulations at different wavelengths, the phase modulation at λ1 is determined solely by the geometric phase. The phase modulation at λ2 comprises both geometric phase and topological phase. in This represents the phase shift at the EP wavelength of the superatomic layer. Therefore, it represents the rotation angle of the unit cell structure forming the metasurface and its phase value at the EP wavelength when it is not rotating. It can be represented 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 multifunctionality was conducted. A metasurface was designed to generate vortex beams with topological charges l=1 and l=2 at two wavelengths (1530nm and 1568nm), respectively. Figure 7 (a) shows the intensity distribution of the output light field at 1530 nm; Figure 7 (b) shows the phase distribution of the output light field at 1530 nm; Figure 7 (c) shows the intensity distribution of the output light field at 1568 nm; Figure 7 (d) shows the phase distribution of the output light field at 1568 nm, and the intensity and phase diagrams at 1530 nm are shown below. Figure 7 (a) and Figure 7 As shown in (b), the disappearance of the beam center intensity caused by the phase helicity can be clearly observed, indicating that the topological charge of the vortex beam is l=1. Then, this scheme shifts the detected wavelength to 1568 nm while maintaining the same observation range. For the same metasurface, this scheme can observe vortex beams with l=2, with a larger radius of the ring intensity and a larger region of zero intensity at the beam center. Figure 7(c). Furthermore, two phase singularities appear in the phase distribution, such as... Figure 7 (d) indicates that its topological charge number has changed to 2. These results strongly demonstrate that the metasurface can independently control the optical field manipulation characteristics at 1530 nm and 1568 nm, realizing wavelength-reused, decoupled vortex beam generation.

[0066] Choosing different metasurface units allows for different wavelength reuse interval values. Here, this scheme selects an additional set of metasurface unit structure parameters, as shown in Table 2. These geometric parameters exhibit small variations in W2 and larger variations in L2. The path formed by these parameters also contains an EP at 1568 nm, but the EP rapidly shifts away with wavelength, causing topological protection to disappear. Therefore, this metasurface can provide a shorter wavelength reuse interval. Figure 8 (a) shows the intensity distribution of the output light field at 1550 nm; Figure 8 (b) shows the phase distribution of the output light field at 1568 nm, such as Figure 8 As shown in (a), this scheme selects the letters “E” and “P” as target holograms and places them in different positions. Figure 8 Simulation results shown in (b) indicate that the holograms presented at wavelengths of 1550 nm and 1568 nm match the target image well. These results verify the ability of non-Hermitian metasurfaces to independently phase-tune two short-interval 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 can achieve short-interval wavelength reuse by strategically selecting the parameters of metasurface unit structures in the parameter space of metasurfaces with singularities. This is expected to be widely used in fields such as information encryption, optical communication, and laser processing.

[0070] Another aspect of the present invention provides an optical system employing the aforementioned non-Hermitian metasurface for short-interval wavelength division multiplexing.

[0071] Those skilled in the art will understand that the exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Whether implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. When implemented in hardware, it can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this invention are programs or code segments used to perform the desired tasks. The programs or code segments can be stored in a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried in a carrier wave.

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

[0073] In this 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 in place of features of other embodiments.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-Hermitian metasurface for short-interval wavelength division multiplexing, characterized in that, The metasurface is provided with multiple supercells, and each supercell is sequentially provided with a first metal layer, an insulating layer and a second metal layer. The top view of the supercell is that of a cube. The second metal layer is provided with a first metal body and a second metal body, both of which are cuboids. In the top view of the supercell, the first metal body and the second metal body are respectively disposed on both sides of the centroid of the top view of the supercell. In the top view of the supercell, a first tilt angle is provided between the width direction of the first metal body and the length direction of the second metal body. In the top view of the supercell, a second tilt angle exists between the line connecting the centroid of the first metal body and the second metal body and the centroid of the top view of the supercell and the edge line of the top view of the supercell. Obtain the first target wavelength and the second target wavelength to obtain the corresponding first phase map and second phase map. Based on the position of the supercell on the metasurface, compare with the preset first phase map to determine the corresponding first phase. Calculate the second tilt angle of the supercell based on the first phase. Based on the position of the supercell on the metastructure surface and referring to a preset second phase diagram, the corresponding second phase is determined; based on the first and second phases, the phase shift value at the non-Hermitian singularity wavelength is calculated, and based on the phase shift value at the non-Hermitian singularity wavelength, the length and width of the second metallic body in the supercell are determined; the second tilt angle and the phase shift value at the non-Hermitian singularity wavelength are calculated according to the following formula: ； in, Indicates the second tilt angle. Indicates the first phase. This represents the phase shift value at the wavelength of the non-Hermitian singular point. This indicates the second phase.

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 in each supercell on the metasurface are all the same, and the height of the second metal body is the same as the height 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 ranges from 350 to 400 nm, the width of the first metal body ranges from 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, characterized in that, In the top view plane of the supercell, the distance between the centroids of the first and second metal bodies and the centroid of the top view plane of the supercell is a first distance.

5. The non-Hermitian metasurface for short-interval wavelength division multiplexing according to claim 3, characterized in that, In the top view plane of the supercell, the centroids of the first and second metal bodies are aligned with the centroid of the top view plane of the supercell.

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

7. An optical system, characterized in that, The optical system employs a non-Hermitian metasurface for short-interval wavelength division multiplexing as described in any one of claims 1 to 6.

Images