Application and verification method of antisymmetric chiral metasurface and phase amplitude regulation and control

Abstract

The invention discloses an application and verification method of antisymmetric chiral metasurface and phase amplitude regulation and control, and belongs to the field of micro-nano optics, the antisymmetric chiral metasurface comprises a surface layer, a middle layer and a back plate layer which are sequentially arranged from top to bottom, and the surface layer is composed of a left semicircular ring and a right semicircular ring; the two ends of the side, facing the right half ring, of the left half ring are bent towards the circle center to form a first protrusion and a second protrusion, one end of the side, facing the left half ring, of the right half ring is bent towards the circle center to form a third protrusion, and the third protrusion and the first protrusion are symmetrically arranged about the circle center. The length of the third protrusion is equal to that of the first protrusion, and the length of the first protrusion is larger than that of the second protrusion. By adopting the application and verification method of the antisymmetric chiral metasurface and phase amplitude regulation and control, by breaking C2 (second-order rotation) symmetry and mirror symmetry, not only can spin decoupling phase control be realized through chiral phase, but also the amplitude of reflected waves can be adjusted by using circular dichroism.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano optical technology, and in particular to an application and verification method of an antisymmetric chiral metasurface and phase amplitude regulation. Background Art

[0002] Chirality is a ubiquitous phenomenon in nature. The chirality of a substance refers to a geometric feature of its structure, which means that it is impossible to overlap with its mirror image through translation or in-plane rotation operations.

[0003] At the same time, the polarization state characterizes the electric field oscillation of light in a plane perpendicular to the propagation direction. In circularly polarized light, the electric field vector can be decomposed into two linearly polarized components. The two perpendicular electric field vectors oscillate with a 90° phase shift and propagate along a spiral trajectory in a clockwise or counterclockwise direction. Due to the different spiral trajectories of the electric field vector, circularly polarized light can be divided into left-handed circularly polarized light (LCP) and right-handed circularly polarized light (RCP).

[0004] Chiral media show unique optical responses to LCP and RCP, but the interaction between chiral materials and chiral light fields in nature is very weak. In order to efficiently control chiral light fields and develop them into optical devices, the academic community has proposed and studied artificially designed chiral metamaterials. In recent years, a two-dimensional version has been developed, called chiral metasurfaces, which can achieve magneto-electric resonance coupling and excite chiral optical responses such as super-strong optical rotation and circular dichroism, and are then used in technical fields such as biochemical substance detection and circular polarization optical display.

[0005] From the perspective of light field control, chiral metasurfaces are one of the important ways to independently control orthogonal circularly polarized electromagnetic waves. Exploring electromagnetic theories with spin decoupling control of LCP and RCP wave components and developing corresponding metasurface devices has become one of the research hotspots in academia.

[0006] In the early days, the only independent phase control method for circularly polarized electromagnetic waves was the Pancharatnam-Berry (PB) phase, that is, when the unit structure rotates by an angle θ, an additional ±2θ phase is introduced into the cross-polarization component of its reflection or transmission, which is conjugated to LCP and RCP. Since the geometric phase has a fixed conjugated change in the phase response to LCP and RCP, this greatly limits the spin decoupling function of the metasurface.

[0007] In 2015, Professor Arbabi published in "Dielectric metasurfaces for complete control of phase and polarization with subwavelength spatial resolution and high transmission" the combination of polarization-space-dependent PB phase and parameter-space-dependent resonant phase. Through the joint design of the two types of phases, the independent phase control of LCP and RCP was realized for the first time, and a variety of wavefront designs were demonstrated. Subsequently, by introducing local interference of neighboring metaatoms, the scheme was extended to the phase and amplitude manipulation of arbitrary orthogonal polarization components. However, the above reports all consider non-chiral structures with mirror symmetry, and need to take into account both geometric phase and resonant phase design requirements.

[0008] In recent years, the chiral phase induced by azimuthal rotation and structural parameter adjustment of chiral meta-atoms has become a new method for the design of spin-decoupled metasurfaces. In 2020, Yuan et al. published in "Independent phase modulation for quadruplex polarization channels enabled by chirality-assisted geometric-phase metasurfaces" that introduced chirality-induced phases by using the relative azimuthal differences of multilayer metal resonators, and completed the circular polarization wavefront design of four channels in combination with the resonant phase; in 2021, Chen et al. proposed in "Metasurfaces with Planar Chiral Meta-Atoms for Spin Light Manipulation" that the use of all-dielectric meta-atoms with C2 symmetry combined with their geometric phases to control spin waves; in the same year, Song et al. reported in "Spin-Selective Full-Dimensional Manipulation of Optical Waves with Chiral Mirror" the topological phase induced by singularities in non-Hermitian chiral meta-atoms, and combined with the PB phase to achieve spin-decoupled wavefront control.

[0009] However, the above-mentioned circularly polarized electromagnetic wave control methods based on achiral or chiral meta-atoms still have room for improvement in terms of theoretical complexity, design difficulty, and computational complexity. Moreover, the combination of the resonant phase or chiral phase with the PB phase requires more theoretical description, and the analysis of the polarization space needs to be considered while exploring the parameter space. In addition, the differentiated control of the wave component amplitudes also shows great difficulty. Summary of the invention

[0010] The purpose of the present invention is to provide an application and verification method of antisymmetric chiral metasurface and phase amplitude control to solve the above-mentioned technical problems.

[0011] To achieve the above-mentioned purpose, the present invention provides an antisymmetric chiral metasurface, comprising a surface layer, an intermediate layer and a backplane layer arranged in sequence from top to bottom, the surface layer is composed of a left semicircular ring and a right semicircular ring, wherein both ends of the left semicircular ring on a side facing the right semicircular ring are bent toward the center of the circle to form a first protrusion and a second protrusion, and one end of the right semicircular ring on a side facing the left semicircular ring is bent toward the center of the circle to form a third protrusion, the third protrusion is symmetrically arranged with the first protrusion about the center of the circle, and the length of the third protrusion is equal to the length of the first protrusion, and the length of the first protrusion is greater than the length of the second protrusion.

[0012] Preferably, the distance between the left semicircular ring and the right semicircular ring is d=10um;

[0013] The width w of the left semicircular ring, the right semicircular ring, the first protrusion, the second protrusion and the third protrusion is 25 um;

[0014] The lengths of the first and third protrusions are h1=65 um, and the length of the second protrusion is h=60 um.

[0015] Preferably, the material of the middle layer is polyimide, with a dielectric constant ε=3.4, a loss tangent tanδ=0.002, and a thickness t1=70 um.

[0016] Preferably, the back plate layer is made of gold, with a thickness of t=200 nm.

[0017] Preferably, the absorptivity of the chiral metasurface to left-handed circularly polarized light is 94.467%, and the absorptivity to right-handed circularly polarized light is 5.659%.

[0018] An antisymmetric chiral metasurface is used for phase-amplitude control, which uses chiral phase and circular dichroism to jointly control the phase and amplitude of the reflected circularly polarized wave component.

[0019] A method for verifying the application of an antisymmetric chiral metasurface in phase amplitude control comprises the following steps:

[0020] S1. Establishing a simulation model: Determine the geometric parameters of the chiral metasurface, and then use electromagnetic simulation software to establish a three-dimensional model of the chiral metasurface, and define the incident wave as left-handed circularly polarized light or right-handed circularly polarized light, and set the operating frequency and boundary conditions, where the operating frequency is in the terahertz band;

[0021] S2, using electromagnetic simulation software to scan the first protrusion, the second protrusion, and the third protrusion of the chiral metasurface to obtain a chiral metasurface simulation unit under multiple parameter configurations;

[0022] S3, simulation analysis: calculate the reflection amplitude and phase of the chiral metasurface simulation unit under each parameter configuration, and select the chiral metasurface simulation unit that meets the expectations based on the calculated reflection amplitude and phase as the final structure of the chiral metasurface;

[0023] S4. The final structure based on the chiral metasurface is functionally verified in a selective polarization scenario.

[0024] Preferably, in step S1, the boundary conditions in the x and y directions are set to unit cell, the boundary condition in the z direction is set to open, and the polarization mode numbers of the maximum value Zmax of the electromagnetic simulation space and the minimum value Zmin of the electromagnetic simulation space are both set to 2;

[0025] In step S2, the first protrusion, the second protrusion and the third protrusion are scanned respectively from 0 um to 160 um with a step length of 2 um.

[0026] Preferably, in step S3, the calculation formula of the reflection amplitude is as follows:

[0027]

[0028] Where R represents the reflection amplitude; R circ Represents the reflection coefficient matrix of circularly polarized waves; r LL and r RR Represent the reflection coefficients of left-handed circularly polarized light and right-handed circularly polarized light respectively; r LR and r RL represents the cross reflection coefficient from left circular polarization to right circular polarization and from right circular polarization to left circular polarization respectively; r xx 、r yy 、r xy and r yx All represent the reflection coefficient matrix elements of linearly polarized waves; i represents the imaginary unit;

[0029] The phase calculation formula is as follows:

[0030]

[0031] In the formula, and represent the phases of left-handed circularly polarized light and right-handed circularly polarized light, respectively. It varies linearly along the x direction. remains unchanged; k represents the linear phase gradient; Indicates the initial phase.

[0032] Preferably, step S4 specifically includes the following steps:

[0033] S41. Set the deflection angle of left-handed circularly polarized light to 30°, and select four superatoms in the parameter space so that A linear phase gradient is formed at intervals of 90°, and the The chiral metasurface with spin-selective deflection is obtained.

[0034] S42, simulating the reflection far-field pattern of the chiral metasurface with spin-selective deflection under the incidence of left-handed circularly polarized light and right-handed circularly polarized light, and obtaining the control effect of the chiral metasurface on the left-handed circularly polarized light and the right-handed circularly polarized light;

[0035] S43. In the case of left-handed circularly polarized light incident on the chiral metasurface, the parameters of the final structure are substituted into the following formula to calculate the reflection angle θ of the left-handed circularly polarized light:

[0036] θ=sin -1 (λ' / Γ) (3);

[0037] In the formula, λ' represents the spatial wavelength; Γ represents the spatial period;

[0038] S44. Compare and verify the reflection angle θ of the left-handed circularly polarized light calculated by formula (3) with the result obtained in the reflection far-field pattern described in step S42 to confirm whether the final structure of the chiral metasurface has achieved the predetermined goal.

[0039] Therefore, the present invention adopts the above-mentioned antisymmetric chiral metasurface and the application and verification method of phase amplitude control, which has the following beneficial effects:

[0040] 1. High selective absorption rate: The chiral metasurface exhibits significantly different absorption characteristics for left-handed circularly polarized light (LCP) and right-handed circularly polarized light (RCP). The absorption rate for LCP is 94.467%, while the absorption rate for RCP is only 5.659%. This highly selective absorption makes the chiral metasurface have potential applications in optical filters, sensors and other photonic devices;

[0041] 2. Geometric design optimization: The surface layer is composed of a left semicircular ring and a right semicircular ring, and the best chiral effect is achieved through the specific geometric design of the first protrusion, the second protrusion, and the third protrusion. These geometric parameters (such as length, width, and distance) are optimized to ensure the best performance. The optimization of geometric parameters not only improves the chiral effect, but also enhances the selectivity and control of light in different polarization states;

[0042] 3. Material selection and performance: The middle layer is made of polyimide material, which has a low dielectric constant and loss tangent, as well as appropriate thickness, which helps to reduce energy loss and improve electromagnetic wave transmission efficiency;

[0043] The backplane layer uses gold material to ensure good conductivity and reflection performance, further enhancing the overall performance of the metasurface;

[0044] 4. Simulation verification: Through the comparison and verification of actual simulation and theoretical formula, it is confirmed that the final structure of the chiral metasurface has achieved the predetermined goal, ensuring the effectiveness and reliability of the design;

[0045] 5. Joint control of phase and amplitude: By using chiral phase and circular dichroism, the phase and amplitude of the reflected circularly polarized wave component of the chiral metasurface can be jointly controlled, which provides the possibility for the development of new optical devices, such as spin-selective optical elements for communication, sensing, imaging and other fields.

[0046] In summary, the present invention can selectively absorb one circularly polarized wave (such as LCP) efficiently under specific conditions, while maintaining a high reflectivity for another circularly polarized wave (such as RCP), thereby achieving more flexible and diverse electromagnetic wave manipulation functions, making it excellent in selective absorption, phase and amplitude regulation, and suitable for a variety of optical applications, especially in terahertz band applications. It has great potential.

[0047] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a surface structure diagram of an antisymmetric chiral metasurface of the present invention.

[0049] Figure 2 The reflection far-field pattern of the antisymmetric chiral metasurface in the simulation experiment, where (a) is the spin-dependent reflection amplitude manipulation pattern based on circular dichroism; (b) is the spin-dependent phase manipulation pattern based on circular dichroism; (c) is the spin-dependent reflection amplitude manipulation pattern based on the chiral phase; (d) is the spin-dependent phase manipulation pattern based on the chiral phase; (e) is the electric field distribution of the 0.58THz metaatom when LCP wave (left-handed polarized light) is incident; (f) is the electric field distribution of the 0.58THz metaatom when RCP wave (right-handed polarized light) is incident;

[0050] Figure 3 The functional verification result diagram of the simulation experiment; (a) (b) Variation diagram of chiral metasurface structural parameters; Variation diagram of chiral metasurface structure parameters; (c) R LL Variation diagram of chiral metasurface structure parameters; (d) R RR (e) is the reflection far-field pattern of the chiral metasurface under the incidence of LCP wave; (f) is the reflection far-field pattern of the chiral metasurface under the incidence of RCP wave.

[0051] Reference numerals

[0052] 1. Left semicircle; 2. First protrusion; 3. Second protrusion; 4. Right semicircle; 5. Third protrusion. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not used to limit the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0054] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices.

[0055] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0056] Conventional double split ring resonators have mirror symmetry and can accumulate geometric phase or linear polarization resonant phase in the path of polarization space or parameter space, but do not have chiral response. When the structure is sheared to break the mirror symmetry and second-order rotational symmetry, obvious chiral phase and circular dichroism may appear at the same time, thereby controlling the phase and amplitude of the reflected wave.

[0057] Based on the above analysis, the present invention is designed as follows: Figure 1 As shown, an antisymmetric chiral metasurface includes a surface layer, an intermediate layer and a backplane layer arranged in sequence from top to bottom, the surface layer consists of a left semicircular ring 1 and a right semicircular ring 4, wherein both ends of the left semicircular ring 1 on the side facing the right semicircular ring 4 are bent toward the center of the circle to form a first protrusion 2 and a second protrusion 3, and one end of the right semicircular ring 4 on the side facing the left semicircular ring 1 is bent toward the center of the circle to form a third protrusion 5, the third protrusion 5 and the first protrusion 2 are arranged symmetrically about the center of the circle, and the length of the third protrusion 5 is equal to the length of the first protrusion 2, and the length of the first protrusion 2 is greater than the length of the second protrusion 3.

[0058] The distance d between the left semicircular ring 1 and the right semicircular ring 4 is 10um; the width w of the left semicircular ring 1, the right semicircular ring 4, the first protrusion 2, the second protrusion 3 and the third protrusion 5 is 25um; the length h1 of the first protrusion 2 and the third protrusion 5 is 65um, and the length h of the second protrusion 3 is 60um.

[0059] The material of the middle layer is polyimide, with a dielectric constant ε=3.4, a loss tangent tanδ=0.002, and a thickness t1=70 um.

[0060] The material of the back plate layer is gold, with a thickness of t=200nm.

[0061] The absorptivity of the chiral metasurface for left-handed circularly polarized light is 94.467%, and the absorptivity for right-handed circularly polarized light is 5.659%.

[0062] An antisymmetric chiral metasurface is used for phase-amplitude control, which uses chiral phase and circular dichroism to jointly control the phase and amplitude of the reflected circularly polarized wave component.

[0063] A method for verifying the application of an antisymmetric chiral metasurface in phase amplitude control comprises the following steps:

[0064] S1. Establishing a simulation model: Determine the geometric parameters of the chiral metasurface, and then use electromagnetic simulation software to establish a three-dimensional model of the chiral metasurface, and define the incident wave as left-handed circularly polarized light or right-handed circularly polarized light, and set the operating frequency and boundary conditions, where the operating frequency is in the terahertz band;

[0065] In step S1, the boundary conditions in the x and y directions are set to unit cell (periodic), the boundary condition in the z direction is set to open (open), and the polarization mode numbers of the maximum value Zmax of the electromagnetic simulation space and the minimum value Zmin of the electromagnetic simulation space are both set to 2;

[0066] S2, using electromagnetic simulation software to scan the first protrusion, the second protrusion, and the third protrusion of the chiral metasurface to obtain a chiral metasurface simulation unit under multiple parameter configurations;

[0067] In step S2, the first protrusion, the second protrusion and the third protrusion are scanned respectively from 0 um to 160 um with a step length of 2 um.

[0068] S3, simulation analysis: calculate the reflection amplitude and phase of the chiral metasurface simulation unit under each parameter configuration, and select the chiral metasurface simulation unit that meets the expectations based on the calculated reflection amplitude and phase as the final structure of the chiral metasurface;

[0069] In step S3, the calculation formula of the reflection amplitude is as follows:

[0070]

[0071] Where R represents the reflection amplitude; R circ Represents the reflection coefficient matrix of circularly polarized waves; r LL and r RR Represent the reflection coefficients of left-handed circularly polarized light and right-handed circularly polarized light respectively; r LR and r RL represents the cross reflection coefficient from left circular polarization to right circular polarization and from right circular polarization to left circular polarization respectively; r xx 、r yy 、r xy and r yx All represent the reflection coefficient matrix elements of linearly polarized waves; i represents the imaginary unit;

[0072] The phase calculation formula is as follows:

[0073]

[0074] In the formula, and represent the phases of left-handed circularly polarized light and right-handed circularly polarized light, respectively. It varies linearly along the x direction. remains unchanged; k represents the linear phase gradient; Indicates the initial phase.

[0075] S4. The final structure based on the chiral metasurface is functionally verified in a selective polarization scenario.

[0076] Step S4 specifically includes the following steps:

[0077] S41. Set the deflection angle of left-handed circularly polarized light to 30°, and select four superatoms in the parameter space so that A linear phase gradient is formed at intervals of 90°, and the The chiral metasurface with spin-selective deflection is obtained.

[0078] S42, simulating the reflection far-field pattern of the chiral metasurface with spin-selective deflection under the incidence of left-handed circularly polarized light and right-handed circularly polarized light, and obtaining the control effect of the chiral metasurface on the left-handed circularly polarized light and the right-handed circularly polarized light;

[0079] Simulation conditions: 8×8 chiral metasurfaces are arranged, each row has the same arrangement structure, one unit changes every two columns, and the four units are linear phase gradient changes. The operating frequency is set to 0.2THz-0.8THz. In terms of boundary condition settings, the boundary conditions in the x and y directions are set to periodic (the coordinate axis is periodic), and the boundary condition in the z direction is set to open (open) to calculate the electromagnetic characteristics of the far-field field;

[0080] S43. In the case of left-handed circularly polarized light incident on the chiral metasurface, the parameters of the final structure are substituted into the following formula to calculate the reflection angle θ of the left-handed circularly polarized light:

[0081] θ=sin -1 (λ' / Γ) (3);

[0082] In the formula, λ' represents the spatial wavelength; Γ represents the spatial period;

[0083] S44. Compare and verify the reflection angle θ of the left-handed circularly polarized light calculated by formula (3) with the result obtained in the reflection far-field pattern described in step S42 to confirm whether the final structure of the chiral metasurface has achieved the predetermined goal.

[0084] Simulation experiment

[0085] Based on the present invention, simulation experiments are carried out and the results are as follows: Figure 2 and Figure 3 As shown by Figure 2 (a) It can be seen that when h1 = 10um and h = 35um, it exhibits obvious circular dichroism, that is, it basically does not reflect LCP waves near the operating frequency, but has a high reflectivity to RCP. Figure 2 (b) It can be seen that near the extreme value of circular dichroism A mutation occurs, and the absorption rates of the chiral metasurface to LCP and RCP waves are 94.467% and 5.659% respectively. The chiral metasurface shows a huge absorption of LCP waves near the operating frequency of 0.35THz, and shows effective reflection of RCP waves in the range of 0.3THz-0.4THz. The reflection difference of the two circularly polarized components measured in a specific direction is defined as CD, and the CD value is as high as 0.899 at 0.3536THz. In addition, the chiral metasurface breaks the C2 symmetry, but due to the existence of the chiral phase, it can still be obtained from Figure 2 (b) and There are differences.

[0086] Depend on Figure 2(c) and (d) show that when h1 = 65um, h = 60um, it can be clearly observed that in the frequency range of 0.3THz to 0.4THz, the reflected co-polarized circularly polarized wave R LL and R RR The reflectivity curves of the chiral metasurface (reflectivity is equal to the square of the reflection coefficient) are basically the same. And in the frequency range of 0.3THz to 0.4THz, the reflection circular polarization phase and There is an obvious phase difference during the transmission process, and the phase can also be independently adjusted, so h1=65um and h=60um are taken.

[0087] Depend on Figure 2 (e) It can be seen that when h1=65um, h=60um, when the incident light beam is left-handed circularly polarized light, the first and third protrusions generate a strong electric field, the incident terahertz wave is stimulated to strongly resonate, the incident electromagnetic wave is converted into ohmic heat, and the terahertz wave enters the lossy polyimide layer and is trapped inside the medium. The signal is attenuated and absorbed, causing dielectric loss. The combination of metal loss and dielectric loss leads to the sensitivity of the chiral metasurface to LCP waves. Figure 2 (f) It can be seen that when the incident light beam is right-handed circularly polarized light, the right semicircular ring only has a weak electric dipole resonance at the port and basically does not absorb RCP, which indicates that the chiral metasurface can achieve efficient selective absorption.

[0088] Depend on Figure 3 (a) and (b) show that by changing the structural parameters Basically, it can achieve a phase coverage of 2π, and present an approximate angular phase gradient in the parameter space. Only a slight phase change of less than π is produced, and the change is approximately linear in the direction of increasing h1. This shows that it is possible to achieve differential phase control of the two circular polarization components.

[0089] Depend on Figure 3 (c) and (d) show that R RR The high amplitude is maintained throughout the parameter space, while R LL There are large amplitude changes in some areas. Therefore, the phase and amplitude of LCP and RCP can be controlled by adjusting the structural parameters and chirality of the chiral metasurface.

[0090] Depend on Figure 3 (e) and (f) show that the reflected beam is almost not deflected when the RCP wave is incident. When the LCP wave is incident, the phase change interval is 90°, and the space size required for one phase cycle is 4P. At the same time, substituting the structural parameters into formula (3) can obtain a reflection angle of 29.4°, which is obtained by Figure 3(e) The read reflection angle is 30° and the error is within an acceptable range, thus proving the effectiveness of the present invention.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. An antisymmetric chiral metasurface, characterized in that: It includes a surface layer, a middle layer and a back plate layer arranged in sequence from top to bottom, the surface layer is composed of a left semicircular ring and a right semicircular ring, wherein both ends of the left semicircular ring on the side facing the right semicircular ring are bent toward the center of the circle to form a first protrusion and a second protrusion, and one end of the right semicircular ring on the side facing the left semicircular ring is bent toward the center of the circle to form a third protrusion, the third protrusion and the first protrusion are arranged symmetrically about the center of the circle, and the length of the third protrusion is equal to the length of the first protrusion, and the length of the first protrusion is greater than the length of the second protrusion.

2. The antisymmetric chiral metasurface according to claim 1, characterized in that: The distance between the left and right semicircular rings is d = 10um; The width w of the left semicircular ring, the right semicircular ring, the first protrusion, the second protrusion and the third protrusion is 25 um; The lengths of the first and third protrusions are h1=65 um, and the length of the second protrusion is h=60 um.

3. The antisymmetric chiral metasurface according to claim 1, characterized in that: The material of the middle layer is polyimide, with a dielectric constant ε=3.4, a loss tangent tanδ=0.002, and a thickness t1=70 um.

4. The antisymmetric chiral metasurface according to claim 1, characterized in that: The material of the back plate layer is gold, with a thickness of t=200nm.

5. The antisymmetric chiral metasurface according to claim 1, characterized in that: The absorptivity of the chiral metasurface for left-handed circularly polarized light is 94.467%, and the absorptivity for right-handed circularly polarized light is 5.659%.

6. The application of the antisymmetric chiral metasurface in phase amplitude control according to any one of claims 1 to 5, characterized in that: The chiral phase and circular dichroism are used to jointly control the phase and amplitude of the reflected circularly polarized wave component.

7. The verification method for the application of the antisymmetric chiral metasurface in phase amplitude control as described in claim 6 above is characterized by: The following steps are involved: S1. Establishing a simulation model: Determine the geometric parameters of the chiral metasurface, and then use electromagnetic simulation software to establish a three-dimensional model of the chiral metasurface, and define the incident wave as left-handed circularly polarized light or right-handed circularly polarized light, and set the operating frequency and boundary conditions, where the operating frequency is in the terahertz band; S2, using electromagnetic simulation software to scan the first protrusion, the second protrusion, and the third protrusion of the chiral metasurface to obtain a chiral metasurface simulation unit under multiple parameter configurations; S3, simulation analysis: calculate the reflection amplitude and phase of the chiral metasurface simulation unit under each parameter configuration, and select the chiral metasurface simulation unit that meets the expectations based on the calculated reflection amplitude and phase as the final structure of the chiral metasurface; S4. The final structure based on the chiral metasurface is functionally verified in a selective polarization scenario.

8. The verification method for the application of the antisymmetric chiral metasurface in phase amplitude control according to claim 7, characterized in that: In step S1, the boundary conditions in the x and y directions are set to unit cell, the boundary condition in the z direction is set to open, and the polarization mode numbers of the maximum value Zmax of the electromagnetic simulation space and the minimum value Zmin of the electromagnetic simulation space are both set to 2; In step S2, the first protrusion, the second protrusion and the third protrusion are scanned respectively from 0 um to 160 um with a step length of 2 um.

9. The verification method for the application of the antisymmetric chiral metasurface in phase amplitude control according to claim 7, characterized in that: In step S3, the calculation formula of the reflection amplitude is as follows: Where R represents the reflection amplitude; R circ Represents the reflection coefficient matrix of circularly polarized waves; r LL and r RR Represent the reflection coefficients of left-handed circularly polarized light and right-handed circularly polarized light respectively; r LR and r RL represents the cross reflection coefficient from left circular polarization to right circular polarization and from right circular polarization to left circular polarization respectively; r xx 、r yy 、r xy and r yx All represent the reflection coefficient matrix elements of linearly polarized waves; i represents the imaginary unit; The phase calculation formula is as follows: In the formula, and represent the phases of left-handed circularly polarized light and right-handed circularly polarized light, respectively. It varies linearly along the x direction. remains unchanged; k represents the linear phase gradient; Indicates the initial phase.

10. The verification method for the application of the antisymmetric chiral metasurface in phase amplitude control according to claim 7, characterized in that: Step S4 specifically includes the following steps: S41. Set the deflection angle of left-handed circularly polarized light to 30°, and select four superatoms in the parameter space so that A linear phase gradient is formed at intervals of 90°, and the The chiral metasurface with spin-selective deflection is obtained. S42, simulating the reflection far-field pattern of the chiral metasurface with spin-selective deflection under the incidence of left-handed circularly polarized light and right-handed circularly polarized light, and obtaining the control effect of the chiral metasurface on the left-handed circularly polarized light and the right-handed circularly polarized light; S43. In the case of left-handed circularly polarized light incident on the chiral metasurface, the parameters of the final structure are substituted into the following formula to calculate the reflection angle θ of the left-handed circularly polarized light: θ=sin -1 (λ' / Γ) (3); In the formula, λ' represents the spatial wavelength; Γ represents the spatial period; S44. Compare and verify the reflection angle θ of the left-handed circularly polarized light calculated by formula (3) with the result obtained in the reflection far-field pattern described in step S42 to confirm whether the final structure of the chiral metasurface has achieved the predetermined goal.

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