Manufacturing method and control method of chiral metasurface device

Abstract

The invention relates to the technical field of chiral metasurface devices, and provides a manufacturing method and a control method of a chiral metasurface device.The manufacturing method comprises the steps that a silicon functional layer with the target thickness is prepared on an optical substrate, the silicon functional layer is etched to prepare a metasurface structure, and a first intermediate product is obtained, the metasurface structure comprises a plurality of square unit cells arranged periodically, each unit cell is penetrated by a first C-shaped aperture and a second C-shaped aperture which are concentric, the outer radius of the first C-shaped aperture is smaller than the inner radius of the second C-shaped aperture, and the plane where the symmetry axis of the first C-shaped aperture is located is perpendicular to the plane where the symmetry axis of the second C-shaped aperture is located. And preparing a graphene layer on the surface of the silicon functional layer of the first intermediate product, and preparing a metal electrode on the surface of the graphene layer to obtain the chiral metasurface device. The objective of the invention is to solve the problems that a chiral metasurface adopted by a device in the prior art is relatively low in quality factor, high circular dichroism and high spectral selectivity are difficult to consider at the same time, and circular dichroism symbols cannot be dynamically reversed.

Description

Technical Field

[0001] This invention relates to the field of chiral metasurface device technology, and in particular to a method for manufacturing and controlling a chiral metasurface device. Background Technology

[0002] Chiral metasurface devices are optoelectronic devices that enhance the chiral interaction between light and matter through metasurfaces composed of micro- and nanostructures. They can differentially control left-handed and right-handed circularly polarized light, have strong response, are easy to integrate, and are widely used in polarization sensing, optical communication, on-chip optical computing and other fields.

[0003] The chiral metasurfaces used in related technologies, such as chiral metasurfaces with metal spiral structures or all-dielectric chiral metasurfaces based on geometric phase or simple structural destruction, have low quality factors (Q values), making it difficult to achieve both high circular dichroism and high spectral selectivity. Furthermore, once the device is fabricated, the direction of the chiral response is locked, making it impossible to dynamically reverse the circular dichroism sign, which limits the device's application in encoding, switching, and complex information processing. Summary of the Invention

[0004] The present invention provides a method for manufacturing and controlling a chiral metasurface device, which at least solves the problems in related technologies where the chiral metasurfaces used in the devices have low quality factors, making it difficult to achieve both high circular dichroism and high spectral selectivity, and are unable to dynamically reverse the circular dichroism sign.

[0005] This invention provides a method for manufacturing a chiral metasurface device, comprising: providing an optical substrate; preparing a silicon functional layer of a target thickness on the optical substrate; etching the silicon functional layer to prepare a metasurface structure, obtaining a first intermediate product, wherein the metasurface structure includes a plurality of periodically arranged square cells, each cell being penetrated by a concentric first C-type aperture and a second C-type aperture, the outer radius of the first C-type aperture being smaller than the inner radius of the second C-type aperture, and the plane containing the symmetry axis of the first C-type aperture being perpendicular to the plane containing the symmetry axis of the second C-type aperture; preparing a graphene layer on the surface of the silicon functional layer of the first intermediate product, obtaining a second intermediate product; and preparing a metal electrode on the surface of the graphene layer of the second intermediate product, thereby obtaining a chiral metasurface device.

[0006] Preferably, before etching the silicon functional layer to prepare the metasurface structure and obtaining the first intermediate product, the above method further includes: performing finite element simulation analysis, and determining the quantitative relationship between the quality factor of the first intermediate product and the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture by means of data fitting; and determining the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture based on the target quality factor and the quantitative relationship, for use in preparing the metasurface structure.

[0007] Preferably, finite element simulation analysis is performed to determine the quantitative relationship between the quality factor of the first intermediate product and the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture through data fitting. This includes: performing transmission spectrum simulation and circular dichroism spectrum simulation to obtain spectral simulation results; establishing coupled mode equations and deriving analytical solutions for the transmission coefficient; and fitting the spectral simulation results and the analytical solutions for the transmission coefficient to determine the quantitative relationship.

[0008] Preferably, the calculation formula used for circular dichroism spectrum simulation includes: ; In the formula, Represents circular dichroism. This represents the transmission coefficient, indicating that both the transmitted and incident light are right-handed circularly polarized. This represents the transmission coefficient when the transmitted light is left-handed circularly polarized and the incident light is right-handed circularly polarized. This represents the transmission coefficient when the incident light is left-handed circularly polarized and the transmitted light is right-handed circularly polarized. This represents the transmission coefficient, indicating that both the transmitted and incident light are left-handed circularly polarized.

[0009] Preferably, before fabricating the silicon functional layer of the target thickness on the optical substrate, the method further includes: determining the target thickness of the silicon functional layer based on performance conditions; the performance conditions at least include supporting Mie resonance in the near-infrared band.

[0010] Preferably, before providing an optical substrate, the method further includes: determining the thickness and refractive index of the optical substrate based on the target thickness of the silicon functional layer.

[0011] The present invention also provides a control method for a chiral metasurface device, wherein the chiral metasurface device is manufactured based on any of the above-described manufacturing methods, and the control method includes: applying a control voltage to a metal electrode; adjusting the Fermi level of a graphene layer based on the control voltage to change the dielectric constant of the graphene layer, thereby controlling the circular dichroism sign of the chiral metasurface device.

[0012] Preferably, the dielectric constant of the graphene layer is changed by adjusting the Fermi level of the graphene layer based on the control voltage, and the formula used includes: ; ; In the formula, This indicates the surface electrical conductivity of the graphene layer. Indicates the contribution of in-band factors. The band-to-band factor contribution is represented by i, the imaginary unit, e, and k. B This represents the Boltzmann constant, and T represents the Kelvin temperature. Let E represent the reduced Planck constant, ω represent the incident light frequency, τ represent the momentum relaxation time, and E represent the time of light in motion. f Represents the Fermi level, ε g ε0 represents the relative permittivity tensor of the graphene layer, ε0 represents the vacuum permittivity, and h0 represents the thickness of the graphene layer.

[0013] Preferably, the chiral metasurface device is used to construct an optical XNOR logic gate, and the control method further includes: determining a first input state based on the magnitude of the Fermi level; determining a second input state based on the magnitude of the incident light wavelength; and determining the output result of the optical XNOR logic gate based on the first input state and the second input state, combined with a preset logic output criterion.

[0014] Preferably, the logic output criteria include: outputting 1 when the circular dichroism amplitude of the chiral metasurface device is greater than 0.5; and outputting 0 when the circular dichroism amplitude is less than or equal to 0.5; wherein the circular dichroism amplitude is related to the size of the Fermi level and the wavelength of the incident light.

[0015] This invention provides a method for manufacturing a chiral metasurface device. A silicon functional layer of a target thickness is prepared on an optical substrate. The silicon functional layer is then etched to prepare a metasurface structure, yielding a first intermediate product. The metasurface structure comprises a plurality of periodically arranged square unit cells, each penetrated by concentric first and second C-shaped apertures. The outer radius of the first C-shaped aperture is smaller than the inner radius of the second C-shaped aperture, and the plane containing the symmetry axis of the first C-shaped aperture is perpendicular to the plane containing the symmetry axis of the second C-shaped aperture. A graphene layer is prepared on the surface of the silicon functional layer of the first intermediate product, and a metal electrode is prepared on the surface of the graphene layer to obtain the chiral metasurface device. Through a 90° orthogonal rotational misalignment design of the concentric double C-shaped apertures, the in-plane mirror symmetry and rotational symmetry of traditional structures are broken. This allows the quasi-continuous bound state, which originally only responded to linearly polarized light, to form an efficient coupling with circularly polarized light, realizing a chiral quasi-continuous bound state and simultaneously forming a positive and negative circular dichroism response. By introducing electrically modulated graphene, the coupling strength of the bound states in the chiral quasi-continuous domain and the circular dichroism response can be dynamically adjusted. This solves the problems in related technologies where the chiral metasurfaces used in devices have low quality factors, making it difficult to achieve both high circular dichroism and high spectral selectivity, and also preventing the dynamic reversal of the circular dichroism sign. Attached Figure Description

[0016] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other embodiments based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the steps of a method for manufacturing a chiral metasurface device according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the structure of a metasurface in an embodiment of the present invention.

[0019] Figure 3 Is with Figure 2 A schematic diagram illustrating the formation mechanism of biphasic quasi-continuous bound states in the corresponding coupled system.

[0020] Figure 4 Is with Figure 2 A schematic diagram of the cross-section of a single unit cell of the corresponding metasurface structure in the XY plane.

[0021] Figure 5 This is a schematic diagram of the photonic band structure of a small-sized annular metasurface in an embodiment of the present invention.

[0022] Figure 6 Is with Figure 5 The corresponding quality factor distribution diagram.

[0023] Figure 7 This is a schematic diagram of the transmission spectrum of the first C-type aperture metasurface during the process of increasing the first opening angle α1 when the incident light is X-polarized in an embodiment of the present invention.

[0024] Figure 8 yes Figure 7 A schematic diagram illustrating the changing trends of quality factors under the corresponding model.

[0025] Figure 9 This is a schematic diagram of the photonic band structure of a large-size annular metasurface in an embodiment of the present invention.

[0026] Figure 10 Is with Figure 9 The corresponding quality factor distribution diagram.

[0027] Figure 11 This is a schematic diagram of the transmission spectrum of the second C-type aperture metasurface during the increase of the second opening angle α2 when the incident light is Y-polarized in an embodiment of the present invention.

[0028] Figure 12 yes Figure 11 A schematic diagram illustrating the changing trends of quality factors under the corresponding model.

[0029] Figure 13 This is a schematic diagram of the photonic band structure of a composite metasurface composed of a periodic array of concentric double-ring silicon thin films, according to an embodiment of the present invention.

[0030] Figure 14 Is with Figure 13 A schematic diagram of the corresponding quality factor simulation results.

[0031] Figure 15 This is a schematic diagram of the photonic band structure of an intrinsic mode of a composite metasurface consisting of a concentric internal annular hole and an external CSA silicon thin film periodic array, as described in an embodiment of the present invention.

[0032] Figure 16 Is with Figure 15 A schematic diagram of the corresponding quality factor simulation results.

[0033] Figure 17 This is one of the far-field polarization distribution diagrams in wave vector space in the embodiments of the present invention.

[0034] Figure 18 This is the second far-field polarization distribution diagram in the wave vector space of the present invention.

[0035] Figure 19 This is a schematic diagram showing the variation of the circular dichroism spectrum with wavelength for a metasurface structure at different first opening angles according to an embodiment of the present invention.

[0036] Figure 20 In the embodiment of this invention, when the first opening angle is 100°, T RR T LR T RL and T LL Transmission spectrum and schematic diagram of circular dichroism test results for chiral Q-BIC1.

[0037] Figure 21 Is with Figure 20 The corresponding Cartesian pole expansion spectrum diagram.

[0038] Figure 22 Is with Figure 20 The corresponding magnetic field distribution diagram.

[0039] Figure 23 In the embodiment of this invention, when the first opening angle is 120°, T RR T LR T RL and T LL Transmission spectrum and schematic diagram of the circular dichroism test results of chiral Q-BIC2.

[0040] Figure 24 Is with Figure 23 The corresponding Cartesian pole expansion spectrum diagram.

[0041] Figure 25 Is with Figure 23 The corresponding magnetic field distribution diagram.

[0042] Figure 26 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC1 when both the incident light and the transmitted light are right-handed circularly polarized light in an embodiment of the present invention.

[0043] Figure 27 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC1 when the incident light is right-handed circularly polarized light and the transmitted light is left-handed circularly polarized light in an embodiment of the present invention.

[0044] Figure 28 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC1 when both the incident light and the transmitted light are left-handed circularly polarized light in an embodiment of the present invention.

[0045] Figure 29 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC1 when the incident light is left-handedly polarized and the transmitted light is right-handedly circularly polarized in an embodiment of the present invention.

[0046] Figure 30 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC2 when both the incident light and the transmitted light are right-handed circularly polarized light in an embodiment of the present invention.

[0047] Figure 31 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC2 when the incident light is right-handed circularly polarized light and the transmitted light is left-handed circularly polarized light in an embodiment of the present invention.

[0048] Figure 32 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC2 when both the incident light and the transmitted light are left-handed circularly polarized light in an embodiment of the present invention.

[0049] Figure 33 This is a schematic diagram of the data and fitting curves corresponding to the chiral Q-BIC2 when the incident light is left-handedly polarized and the transmitted light is right-handedly circularly polarized in an embodiment of the present invention.

[0050] Figure 34 This is a schematic flowchart of a control method for a chiral metasurface device according to an embodiment of the present invention.

[0051] Figure 35 This is a schematic diagram of the cell structure of a chiral quasi-continuous domain bound state composite metasurface based on graphene in an embodiment of the present invention.

[0052] Figure 36 This is a schematic diagram of the dynamic control results of chiral transmission spectrum in an embodiment of the present invention. Detailed Implementation

[0053] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0054] Chiral metasurface devices are optoelectronic devices that enhance the chiral interaction between light and matter through metasurfaces composed of micro- and nanostructures. They can differentially control left-handed and right-handed circularly polarized light, have strong response, are easy to integrate, and are widely used in polarization sensing, optical communication, on-chip optical computing and other fields.

[0055] The chiral metasurfaces used in related technologies, such as chiral metasurfaces with metal spiral structures or all-dielectric chiral metasurfaces based on geometric phase or simple structural destruction, have low quality factors (Q values), making it difficult to achieve both high circular dichroism and high spectral selectivity. Furthermore, once the device is fabricated, the direction of the chiral response is locked, making it impossible to dynamically reverse the circular dichroism sign, which limits the device's application in encoding, switching, and complex information processing.

[0056] The following is a detailed explanation of some technical terms in the embodiments of this invention.

[0057] The quality factor (Q value) is the ratio of stored energy to consumed energy in a resonant system, which can measure the energy storage efficiency and energy loss of the resonant system.

[0058] Circular dichroism (CD) is an important physical quantity that measures the difference in absorption or transmission of left- and right-circularly polarized light by a material or device.

[0059] Bound states in the Continuum (BIC) are special eigenmodes that exist within the radiation continuous spectrum but remain in a non-radiative state.

[0060] By introducing an asymmetry parameter into an all-dielectric metasurface to break structural symmetry, an ideal BIC can be transformed into a quasi-continuous bound state (quasi-BIC). This quasi-BIC mode establishes a weak coupling with the free-space radiation channel, thereby exciting a Fano resonance with an extremely high quality factor in the far field.

[0061] Please refer to Figure 1 As shown, the present invention provides a method for manufacturing a chiral metasurface device, including steps S101 to S105.

[0062] Step S101: Provide an optical substrate.

[0063] Step S102: Prepare a silicon functional layer of the target thickness on the optical substrate.

[0064] Step S103: Etch the silicon functional layer to prepare a metasurface structure to obtain a first intermediate product. The metasurface structure includes a plurality of periodically arranged square cells. Each cell is penetrated by a concentric first C-shaped aperture and a second C-shaped aperture. The outer radius of the first C-shaped aperture is smaller than the inner radius of the second C-shaped aperture. The plane containing the axis of symmetry of the first C-shaped aperture is perpendicular to the plane containing the axis of symmetry of the second C-shaped aperture.

[0065] Step S104: Prepare a graphene layer on the surface of the silicon functional layer of the first intermediate product to obtain the second intermediate product.

[0066] In step S105, a metal electrode is prepared on the graphene layer surface of the second intermediate product to obtain a chiral metasurface device.

[0067] The optical substrate can be, but is not limited to, quartz or sapphire. This embodiment will be described using quartz as an example.

[0068] In any unit cell, the unit cell, the first C-type aperture and the second C-type aperture in the unit cell are concentric.

[0069] The metasurface structure provided in this embodiment is derived from a toroidal aperture metasurface. While toroidal aperture metasurfaces support high-Q resonance modes, they do not exhibit inherent optical chirality due to their high in-plane symmetry. By introducing a narrow slit to form a C-shaped aperture (CSA), the symmetry is improved from C... ∞v Reduced to a single mirror C 1h This transforms the symmetrically protected BIC into a quasi-BIC that can be effectively accessed by incident radiation.

[0070] The plane containing the axis of symmetry of the first C-type aperture is perpendicular to the plane containing the axis of symmetry of the second C-type aperture. That is, the combination of the first and second C-type apertures introduces orthogonal rotational misalignment, which can eliminate the remaining in-plane mirror symmetry. This compact metasurface unit structure allows two originally isolated polarization-selective resonances to coherently hybridize, thereby producing a significant chiral response that is forbidden in highly symmetric metasurface designs.

[0071] Please refer to Figure 2 As shown, Figure 2 Each cell of the metasurface structure on the left side of the middle section is etched with only the first C-type aperture. Under linearly polarized light irradiation in the X direction, it supports accidental quasi-continuous domain bound states, denoted as quasi-BIC1 (Quasi-BIC1 or Q-BIC1). Figure 2 The metasurface structure on the right side of the middle section has only a second C-type aperture etched in each unit cell. Under linearly polarized light in the Y direction, it supports a random quasi-continuous domain bound state, denoted as quasi-BIC2 (Quasi-BIC2 or Q-BIC2).

[0072] Figure 2 Each cell of the metasurface structure located in the middle is etched with a concentric first C-type aperture and a second C-type aperture. This metasurface structure is composed of an array formed by the periodic arrangement of the cell cells, which is the metasurface structure used in the manufacturing method provided in this embodiment. Under circularly polarized light irradiation, it can support bipolar quasi-continuous domain bound states, which are denoted as chiral quasi-BIC1 and chiral quasi-BIC2, respectively.

[0073] Specifically, due to the mirror symmetry of the first and second C-type apertures, each aperture alone lacks inherent chirality. However, when the first and second C-type apertures are concentrically arranged and orthogonal rotational misalignment is introduced, the rotational symmetry of the resulting metasurface structure in the XY plane is broken. Therefore, linearly polarized light in the X direction can excite Q-BIC1 in the first C-type aperture, while linearly polarized light in the Y direction can excite Q-BIC2 in the second C-type aperture.

[0074] It should be noted that the metasurface structure provided in this embodiment not only retains the inherent random quasi-continuous bound state (Q-BIC) characteristics of a single aperture under linearly polarized light, but also allows the positive and negative circular dichroism associated with the chiral quasi-continuous bound state to manifest simultaneously, such as... Figure 3 As shown. Figure 3 This is a schematic diagram of the formation mechanism of bichiral quasi-continuous bound states in a coupled system. Under a specific incident light polarization direction, orthogonal linearly polarized continuous bound states (BIC) are first formed in the system, and then further transformed into positive and negative chiral quasi-continuous bound states.

[0075] The schematic diagram of a single unit cell of the above-mentioned metasurface structure in the XY plane provided in this embodiment is shown below. Figure 4 As shown, P x P represents the lattice constant of a periodic aperture array extending along the X-direction. y L represents the lattice constant of the periodic aperture array extending along the Y direction, and L represents the side length of the square silicon unit cell.

[0076] Within each unit structure, the blue area represents the silicon layer, and the white area represents air. The geometric parameters of the first C-type aperture include the inner radius R1, the outer radius R2, and the first opening angle α1, which is symmetrical about the XZ plane. The geometric parameters of the second C-type aperture include the outer radius R3, the width D, and the opening angle α2, which is symmetrical about the YZ plane. The outer radius R2 of the first C-type aperture is smaller than the inner radius of the second C-type aperture.

[0077] The width of the first C-shaped aperture can be determined by the difference between its outer radius R2 and inner radius R1, and the inner radius of the second C-shaped aperture can be determined by the difference between its outer radius R3 and width D.

[0078] For example, silicon functional layers are prepared by magnetron sputtering or plasma-enhanced chemical vapor deposition (PECVD). Metasurface structures are prepared by electron beam lithography and reactive ion etching. Graphene layers are prepared using a wet transfer process. Metal electrodes are prepared by evaporation.

[0079] This embodiment achieves high quality factor resonance by precisely designing the symmetry of the metasurface unit structure, enabling continuous-domain or quasi-continuous-domain bound states to be effectively excited under left- or right-handed circularly polarized light incident conditions. This maintains the high quality factor resonance characteristics even under circularly polarized excitation conditions. Compared to related BIC metasurfaces, the metasurface structure provided in this embodiment maintains high quality factor resonance under circularly polarized light excitation conditions.

[0080] This embodiment introduces a high-Q quasi-continuous domain bound state mechanism into a subwavelength-scale structure, making the circular dichroism response dominated by narrow linewidth resonance, thereby achieving a chiral optical response that simultaneously possesses high spectral selectivity and a large circular dichroism difference.

[0081] This embodiment breaks the in-plane mirror symmetry and rotational symmetry of traditional structures by using a 90° orthogonal rotational misalignment design with concentric double C-shaped apertures. This allows the quasi-continuous domain bound states, which originally only responded to linearly polarized light, to form efficient coupling with circularly polarized light, achieving chiral quasi-continuous domain bound states and simultaneously forming a positive and negative circular dichroism response. Precise control of the positive and negative circular dichroism resonance bands and amplitudes can be achieved by adjusting the geometric opening angles of the first and / or second C-shaped apertures. Compared to metasurfaces in related technologies that employ complex multimode or three-dimensional structures, the metasurface structure provided in this embodiment has lower design and manufacturing difficulty.

[0082] This embodiment introduces graphene, an electrically modulated material, to achieve dynamic adjustment of the coupling strength of the bound states in the chiral quasi-continuous domain and the circular dichroism response, thereby meeting the requirements of optical logic operations and reconfigurable photonic devices for rapid and reversible control.

[0083] In summary, the manufacturing method provided in this embodiment can solve the problems in related technologies where the chiral metasurfaces used in the devices have low quality factors, making it difficult to achieve both high circular dichroism and high spectral selectivity, and are unable to dynamically reverse the circular dichroism sign.

[0084] Preferably, in step S102, before fabricating the silicon functional layer of the target thickness on the optical substrate, the method further includes: determining the target thickness of the silicon functional layer based on performance conditions. The performance conditions at least include support for Mie resonance in the near-infrared band.

[0085] For example, the target thickness of the silicon functional layer is set to 140 nm.

[0086] Preferably, before providing an optical substrate in step S101, the method further includes determining the thickness and refractive index of the optical substrate based on the target thickness of the silicon functional layer.

[0087] For example, when the target thickness of the silicon functional layer is set to 140 nm, quartz with a refractive index of 1.45 and a thickness of 310 nm is selected as the optical substrate. Quartz is a natural crystalline variant of silicon dioxide.

[0088] Preferably, before etching the silicon functional layer to prepare the metasurface structure and obtaining the first intermediate product in step S103, the method further includes: performing finite element simulation analysis to determine the quantitative relationship between the quality factor of the first intermediate product and the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture through data fitting. Based on the target quality factor and the quantitative relationship, the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture are determined for the preparation of the metasurface structure.

[0089] Furthermore, finite element simulation analysis was performed. Through data fitting, the quantitative relationship between the quality factor of the first intermediate product and the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture was determined. This included: performing transmission spectrum simulation and circular dichroism spectrum simulation to obtain spectral simulation results. Coupled-mode equations were established, and analytical solutions for the transmission coefficient were derived. The spectral simulation results and the analytical solutions for the transmission coefficient were then fitted to determine the quantitative relationship.

[0090] Specifically, with Figures 2 to 4Taking the metasurface structure shown as an example, incident light is perpendicularly incident on the silicon film and propagates along the negative Z-direction. Finite element method simulation is performed using COMSOL Multiphysics, with a quartz substrate as the optical substrate. The material parameters of silicon and quartz are taken from the Palik handbook. Absorption boundary conditions are set to apply a perfectly matched layer along the Z-direction to eliminate back reflection and ensure absorption at all frequencies and incident angles. Periodic boundary conditions are enforced in the X and Y directions to accurately simulate the behavior of the metasurface unit structure.

[0091] This embodiment utilizes Chiral Temporal Coupled-Mode Theory (CMT) to analyze the optical response of the aforementioned structure, including the temporal evolution of the transmission amplitude and the correspondence between the incident and emitted waves. For chiral metasurfaces, their unique responses to left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) light result in distinctly different coupling behaviors. The amplitude A of the resonant mode is described. I The master equation for the output wave vector b is: ; In the formula, A I γ represents the complex amplitude of the resonance mode, ω represents the resonance frequency, and γ represents the complex amplitude of the resonance mode. I S represents the attenuation rate caused by radiation loss. I Let D represent the scattering matrix. I This represents the coupling matrix connecting the resonance with the incident and outgoing waves.

[0092] a represents the input wave vector from port I and port II, and b represents the input and output wave vectors from port I and port II. ; In the formula, the subscript L represents left-handed circularly polarized light (LCP), and the subscript R represents right-handed circularly polarized light (RCP).

[0093] To study the properties of chiral metasurfaces, it is necessary to analyze the interactions between different circularly polarized states. Therefore, the scattering matrix S I It contains a cross-polarization term, which allows left-handed circularly polarized light to be converted into right-handed circularly polarized light; through the scattering matrix S I By introducing off-diagonal elements, right-handed circularly polarized light can be converted into left-handed circularly polarized light.

[0094] Using matrix C I This describes the direct transmission process from the incident port to the exit port, a process that does not involve resonant modes. In an ideal chiral system, this direct transmission characteristic varies with frequency and exhibits an asymmetric response to left-handed and right-handed circularly polarized light. If each port of the two-port chiral metasurface can handle both polarization states, then matrix C...I It is a 4×4 matrix used to characterize the direct transmission relationship from the four incident channels to the four exit channels: ; use For matrix C I Explain each item in the text. The polarization state of the incident light is represented as The polarization state of the emitted light is And from the port to port The complex amplitude coefficient of direct transmission, where, Represents element R or element T. and Both are used to represent left-handed circularly polarized light (subscript L) or right-handed circularly polarized light (subscript R). and Both are used to represent port I or port II.

[0095] To maintain the time-reversal symmetry of the system, matrix C I Must satisfy unitarity: This ensures the reversibility of the transmission process and the conservation of energy.

[0096] The coupling matrix D connecting the resonance with the incident and outgoing waves I It can be defined as: ; In the formula, This represents the coupling coefficient between the resonant mode at port I and the right-hand circularly polarized light. This represents the coupling coefficient between the resonant mode at port I and the left-handed circularly polarized light. This represents the coupling coefficient between the resonant mode at port II and the right-hand circularly polarized light. This represents the coupling coefficient between the resonant mode at port II and the left-handed circularly polarized light.

[0097] Constrained by time reversal symmetry and energy conservation, the coupling matrix D I The following relationship must be satisfied: ; Considering Substitute S I a=C I a+D I A I We can obtain: ; Considering the complex interactions between different circularly polarized states in a chiral metasurface, the scattering matrix S IIt can be expanded to include detailed coupling terms, specifically in the following form: .

[0098] Furthermore, the scattering matrix S I This can be represented by the Fano line type function: ; ; Finally, the transmission coefficient from port I to port II can be expressed as follows: .

[0099] For example, quartz with a refractive index of 1.45 and a thickness of 310 nm is selected as the transparent optical substrate, and the silicon functional layer is a high-refractive-index silicon thin film with a thickness precisely controlled at 140 nm, such as a silicon thin film with a refractive index of 3.45. The metasurface unit structure is based on a subwavelength periodicity (P... x =P y The silicon unit cells (with a diameter of 900 nm) are arranged in a square array, with a side length L of 850 nm. Each square silicon unit cell contains a set of concentric double C-shaped aperture structures. The first C-shaped aperture has an inner radius R1 = 130 nm and an outer radius R2 = 200 nm, with a first opening angle α1 symmetric about the XZ plane. The second C-shaped aperture has an outer radius R3 = 250 nm and a width D = 75 nm, with a second opening angle α2 symmetric about the YZ plane. The axes of symmetry of the first and second C-shaped apertures are orthogonally offset at 90° in the XY plane, breaking the C2 rotational symmetry of the unit cell structure and thus introducing the geometric phase perturbation required to generate a chiral response.

[0100] When the first opening angle α1 and the second opening angle α2 are zero, the metasurface unit degenerates into a highly symmetric annular hole structure. A continuous domain bound state can be found at the center of the Brillouin zone, where radiation loss is completely suppressed, exhibiting a theoretically infinite quality factor. The evolution from the accidental continuous domain bound state (Accidental BIC) to the quasi-continuous domain bound state (Quasi-BIC) can be achieved by manipulating geometric parameters.

[0101] First, a metasurface unit structure based on a ring-shaped hole was constructed. The inner radius of the small-sized ring structure was set to 130 nm and the outer radius to 200 nm. Band structure simulations showed that this structure possesses an eigenmode with zero radiation loss at the Brillouin zone center (Γ point, approximately 238 THz), i.e., an ideal BIC mode, where the quality factor (Q value) tends to infinity. With the outer radius of the large-sized ring structure set to 250 nm and the width to 75 nm, another ideal BIC mode was also observed at the Γ point (approximately 243.5 THz).

[0102] Next, by introducing an opening into the ring structure, it is transformed into a CSA structure, thereby introducing a radiation channel. Taking a small-sized ring structure as an example, while keeping the incident light linearly polarized in the X direction, the opening angle of the small-sized ring structure is gradually increased from 0° to 30°. As the opening angle increases, the original BIC mode leaks and transforms into Quasi-BIC, which is manifested in the transmission spectrum as a Fano resonance peak with a redshift and enhanced intensity.

[0103] Further quantitative analysis showed that the quality factor (Q value) of the Quasi-BIC decreased significantly with the increase of the aperture angle. Data fitting verified that the Q value and the aperture angle follow the inverse quadratic law. This law also applies to the evolution process of the large-size ring structure under Y-direction linearly polarized light excitation, confirming that radiation loss can be precisely controlled by geometric parameters.

[0104] Figures 5 to 12 This is used to illustrate the evolution of BIC and Quasi-BIC in toroidal metasurfaces and CSA metasurfaces.

[0105] Photonic bandgap structures of small-sized toroidal metasurfaces, such as Figure 5 As shown, the corresponding quality factor distribution is as follows: Figure 6 As shown, the continuous domain bound states at point Γ are marked by solid red circles. Figure 7 The transmission spectrum of the first C-type aperture (first CSA) metasurface during the increase of the first opening angle α1 when the incident light is X-polarized shows the tunable Fano resonance characteristics and the generation process of Quasi-BIC. Figure 8 for Figure 7 The diagram shows the trend of quality factor change under the corresponding mode. The quality factor decreases from infinity as the first opening angle α1 increases, and shows a quadratic inverse trend.

[0106] Large-size toroidal metasurface photonic band structure, such as Figure 9 As shown, the corresponding quality factor distribution is as follows: Figure 10 As shown, the continuous domain bound states at point Γ are marked by solid purple circles. Figure 11 The transmission spectrum of the second C-type aperture (second CSA) metasurface when the incident light is Y-polarized is observed as the second opening angle α2 increases, showing the redshifted Fano resonance and the evolution of the bound state in the quasi-continuous domain. Figure 12 for Figure 11 The diagram shows the trend of quality factor change under the corresponding mode. The quality factor decreases inversely with the increase of the second opening angle α2, indicating that its coupling effect with the far field is enhanced.

[0107] Furthermore, the generation and topological properties of the BIC (Brillouin Interval) of the composite metasurface structure were analyzed. An ideal, highly symmetric unit cell structure composed of concentric double rings (with inner and outer opening angles of 0°) was constructed to verify the initial BIC characteristics. Band structure simulations showed that this structure supports two symmetry-protected bound modes at the Brillouin zone center (Γ point): BIC1 with a frequency of approximately 239.53 THz and BIC2 with a frequency of approximately 248.83 THz. Magnetic field distributions indicated that BIC1 exhibits anti-vortex characteristics, while BIC2 exhibits counterclockwise vortex characteristics. In the far-field polarization diagram, these two modes appear as polarization singularities (V points). The topological charges of BIC1 and BIC2, calculated using the topological charge formula, are qtopological and qtopological, respectively. BIC1 =+1 and q BIC2 =-1, Γ point represents the vortex center of the linearly polarized field; at this time, due to the high symmetry of the structure, the Q value is theoretically infinite, and the structure does not exhibit chiral characteristics.

[0108] Subsequently, keeping the inner ring closed, the outer ring is set to have a second opening angle of 100°, resulting in a second C-shaped aperture, thereby breaking the C-shaped structure. ∞v Rotational symmetry is maintained, but mirror symmetry about the YZ plane is still preserved. Band analysis shows that the reduction in symmetry introduces radiation channels, causing the original BIC modes to diverge: BIC1 (approximately 243 THz), protected by the YZ mirror symmetry, continues to maintain an extremely high Q value; while BIC2 (approximately 237 THz) evolves into a leakage resonance mode with a finite Q value. Topologically, the original V point splits into two C points (C- and C+) with opposite circular polarization states, each C point having a half-integer topological charge of q = +1 / 2; due to the presence of mirror symmetry, these two C points are strictly confined to the symmetry line (L-line) in momentum space, at which point the structure exhibits anisotropy but does not yet possess significant intrinsic chirality.

[0109] By setting the inner annulus to have a first opening angle, a first C-shaped aperture is obtained. This first opening angle is further increased, and the opening directions of the first and second opening angles are orthogonally staggered, thus breaking the remaining YZ mirror symmetry and causing the structure to completely lose its mirror and rotational symmetry in the plane. With the increase of the asymmetry parameter, the C- and C+ points in momentum space are no longer bound to the symmetry line but migrate significantly towards the diagonal direction in k-space. This asymmetric distribution of C points in k-space means that near the perpendicular incident point (Γ point), there is a significant difference in the radiative coupling efficiency of left-handed and right-handed circularly polarized light. It is this topological charge splitting and migration mechanism induced by complete symmetry breaking that coherently couples the originally orthogonal linearly polarized BIC modes, ultimately forming a high-quality factor chiral Quasi-BIC capable of selectively responding to specific circularly polarized light.

[0110] Within the first Brillouin zone, a composite metasurface composed of a periodic array of concentric double-ring silicon thin films exhibits a photonic band structure as follows: Figure 13 As shown, the corresponding quality factor simulation calculation results are as follows: Figure 14 As shown.

[0111] Within the first Brillouin zone, a composite metasurface consisting of a periodic array of concentric internal annular apertures and external CSA (second C-type aperture) silicon thin films exhibits an intrinsic mode photonic band structure as follows: Figure 15 As shown, the corresponding quality factor simulation calculation results are as follows: Figure 16 As shown.

[0112] Figure 17 It is one of the far-field polarization distribution diagrams in wave vector space, corresponding to chiral quasi-BIC1. Figure 18 This is the second far-field polarization distribution diagram in wave vector space, corresponding to chiral quasi-BIC2. Figure 17 and Figure 18 The blue elliptical dots represent left-handed polarization states, and the red elliptical dots represent right-handed polarization states.

[0113] When the first C-type aperture and the second C-type aperture coexist and are orthogonally staggered, the two Quasi-BICs originally excited by orthogonally linearly polarized light coherently couple. Under circularly polarized light illumination, this coupling leads to chiral hybridization of the modes, thereby forming a chiral Quasi-BIC at a specific wavelength. This results in significantly different transmission responses of the device to left-handed and right-handed circularly polarized light, i.e., significant circular dichroism. Setting both the first aperture angle α1 and the second aperture angle α2 to 100°, the corresponding chiral metasurface device excites the first chiral quasi-continuous bound state (ChiralQuasi-BIC 1) at a wavelength of approximately 1242 nm.

[0114] To quantitatively characterize the chiral optical response of the device, the calculation formula used in this embodiment for circular dichroism spectroscopy simulation includes: ; In the formula, Represents circular dichroism. This represents the transmission coefficient, indicating that both the transmitted and incident light are right-handed circularly polarized. This represents the transmission coefficient when the transmitted light is left-handed circularly polarized and the incident light is right-handed circularly polarized. This represents the transmission coefficient when the transmitted light is right-handed circularly polarized and the incident light is left-handed circularly polarized. This represents the transmission coefficient when both the transmitted and incident light are left-handed circularly polarized. The above formula can be used to calculate transmission-type circular dichroism.

[0115] The metasurface structure provided in this embodiment exhibits the following curves showing the variation of its circular dichroism spectrum with wavelength under different first opening angles: Figure 19 As shown.

[0116] When the first opening angle is 100°, T RR T LR T RL and T LL Transmission spectra and circular dichroism test results of chiral Q-BIC1 are as follows: Figure 20 As shown, the corresponding Cartesian multipole expansion spectrum is as follows: Figure 21 As shown, the corresponding magnetic field distribution is as follows: Figure 22 As shown.

[0117] When the first opening angle is 120°, T RR T LR T RL and T LL Transmission spectra and circular dichroism test results of chiral Q-BIC2 are as follows: Figure 23 As shown, the corresponding Cartesian multipole expansion spectrum is as follows: Figure 24 As shown, the corresponding magnetic field distribution is as follows: Figure 25 As shown.

[0118] Spectral simulation results show that at the resonance wavelength of 1242 nm, T RR It remains at a high level of approximately 0.48, with extremely low cross-polarization components; while the same-polarization transmission component T of left-handed circularly polarized light... LL The light intensity was drastically suppressed to near zero, exhibiting significant asymmetric absorption and scattering characteristics. Calculations based on the aforementioned formula show that the device achieved a positive circular dichroism peak of +0.998 at this wavelength, with a resonant linewidth (FWHM) of only 0.28 nm, demonstrating an extremely high quality factor. Multipole expansion mode analysis revealed that this mode is dominated by the electric quadrupole (EQ) and the toroidal dipole (TD), and their coherent superposition leads to selective blocking of LCP light.

[0119] Subsequently, keeping the second aperture angle constant at 100°, the first aperture angle was increased to 120°. At approximately 1268 nm, the device excited a second chiral resonance mode (Chiral Quasi-BIC 2). At this point, the spectral response is: T LL A deep valley of transmission resonance appeared (dropped to approximately 0.04), while T... RR The value is 0.36. Substituting into the CD calculation formula, the circular dichroism value in this mode is -0.69, achieving negative circular dichroism. Through multipole expansion mode analysis, this mode is mainly dominated by magnetic quadrupoles (MQ).

[0120] The experimental data were verified based on the chiral temporal coupled-mode principle. Coupled-mode equations incorporating complex coupling coefficients were established, analytical solutions for the transmission coefficients were derived, and the results were fitted to simulation results. The fitted curves highly overlapped throughout the resonance band, as shown below. Figures 26 to 33 As shown.

[0121] Figures 26 to 29 The CMT fitting results for chiral Q-BIC1 are used to illustrate this. Figure 26 These are the data and fitting curves for chiral Q-BIC1 when both the incident and transmitted light are right-handed circularly polarized. Figure 27 This shows the data and fitting curves for chiral Q-BIC1 when the incident light is right-handed circularly polarized and the transmitted light is left-handed circularly polarized. Figure 28 These are the data and fitting curves for chiral Q-BIC1 when both the incident and transmitted light are left-handed circularly polarized. Figure 29 These are the data and fitting curves corresponding to chiral Q-BIC1 when the incident light is left-handedly polarized and the transmitted light is right-handedly circularly polarized.

[0122] Figures 30 to 33 The CMT fitting results for chiral Q-BIC2 are used to illustrate this. Figure 30 These are the data and fitted curves for chiral Q-BIC2 when both the incident and transmitted light are right-handed circularly polarized. Figure 31 This shows the data and fitted curves for chiral Q-BIC2 when the incident light is right-handed circularly polarized and the transmitted light is left-handed circularly polarized. Figure 32 This shows the data and fitting curves for chiral Q-BIC2 when both the incident and transmitted light are left-handed circularly polarized. Figure 33 These are the data and fitting curves corresponding to chiral Q-BIC2 when the incident light is left-handedly polarized and the transmitted light is right-handedly circularly polarized.

[0123] Please refer to Figure 34 As shown, this invention also provides a control method for a chiral metasurface device, which is manufactured based on any of the above-described manufacturing methods provided in this invention. The control method includes steps S201 and S202. This method addresses the problems in related technologies where the chiral metasurfaces used in devices have low quality factors, making it difficult to simultaneously achieve high circular dichroism and high spectral selectivity, and also preventing dynamic reversal of the circular dichroism sign.

[0124] Step S201: Apply a control voltage to the metal electrode.

[0125] Step S202: Adjust the Fermi level of the graphene layer based on the control voltage to change the dielectric constant of the graphene layer, which is used to control the circular dichroism sign of the chiral metasurface device.

[0126] Figure 35This is a schematic diagram of the cell structure of a chiral quasi-continuous domain bound-state composite metasurface based on graphene. In this embodiment, graphene is considered an effective conductive surface due to its ultrathin properties. Utilizing the high dependence of graphene surface conductivity on the Fermi level (i.e., following the Kubo formula), 0.48 eV and 0.50 eV are selected as the critical modulation states at an ambient temperature of 300 K and a relaxation time of 0.5 ps. Because the chiral quasi-BIC mode has an extremely high quality factor, even a small change in the Fermi level is sufficient to alter the dielectric constant of graphene, thereby disrupting or reconstructing the critical coupling conditions of the mode, leading to a dramatic switching effect in the circular dichroism amplitude. The dynamic modulation results of the chiral transmission spectrum are as follows: Figure 36 As shown.

[0127] Preferably, in step S202, the Fermi level of the graphene layer is adjusted based on the control voltage to change the dielectric constant of the graphene layer, and the formula used includes: ; ; In the formula, This indicates the surface electrical conductivity of the graphene layer. Indicates the contribution of in-band factors. The band-to-band factor contribution is represented by i, the imaginary unit, e, and k. B This represents the Boltzmann constant, and T represents the Kelvin temperature. Let E represent the reduced Planck constant, ω represent the incident light frequency, τ represent the momentum relaxation time, and E represent the time of light in motion. f Represents the Fermi level, ε g ε0 represents the relative permittivity tensor of the graphene layer, ε0 represents the vacuum permittivity, and h0 represents the thickness of the graphene layer.

[0128] The momentum relaxation time τ is chosen to be 0.5 ps to ensure simulation fidelity, and the thickness h0 of the graphene layer (monolayer graphene) can be set to 0.34 nm.

[0129] The real and imaginary parts of the dielectric constant of graphene exhibit different variation patterns at different wavelengths, with the difference being particularly significant near the boundary wavelengths. This characteristic can be used to switch between lossy and lossless states by controlling the Fermi energy of graphene, which is crucial for the realization of chiral quasi-continuous domain confinement.

[0130] It should be noted that in this embodiment, the Fermi level of graphene is tuned within a narrow range, so its interband contribution remains almost unchanged, while the small change in effective loss caused by intraband effects is greatly amplified by the bound states of the high-Q chiral quasi-continuum domain. By utilizing the strong perturbation effect of graphene's loss characteristics on the high-Q chiral BIC mode, the switching control of transmission spectrum and circular dichroism can be achieved.

[0131] Preferably, when the chiral metasurface device is used to construct an optical XNOR logic gate, the control method provided in this embodiment further includes: determining a first input state based on the magnitude of the Fermi level; determining a second input state based on the magnitude of the incident light wavelength; and determining the output result of the optical XNOR logic gate based on the first and second input states, combined with a preset logic output criterion.

[0132] The logic output criteria can be determined by those skilled in the art based on the actual application device and a limited number of experiments.

[0133] Preferably, the logic output criteria include: outputting 1 when the circular dichroism amplitude of the chiral metasurface device is greater than 0.5, and outputting 0 when the circular dichroism amplitude is less than or equal to 0.5. The circular dichroism amplitude is related to the magnitude of the Fermi level and the wavelength of the incident light.

[0134] For example, the graphene Fermi level state is input IN. A When the Fermi level is 0.48 eV, INA = 0; when the Fermi level is 0.50 eV, INA = 1. Taking the short wavelength band as an example, the corresponding logic IN is 1240.9 nm. B1 =0, corresponding to logic IN when the incident light wavelength is 1241.9 nm. B1 =1. The logic output criterion is whether the output circular dichroism amplitude |CD| is greater than 0.5, that is, 1 when |CD|>0.5, and 0 when |CD|≤0.5, as shown in Table 1.

[0135] Table 1 Truth Table of Short-Wavelength Chiral Logic Gates

[0136] Combination Figure 36 Please provide the following explanation.

[0137] When the input is (0,0), the system is in a low-loss resonant state and wavelength matching, with a measured |CD| of 0.97 and an output of 1.

[0138] When the input is (0,1), the incident wavelength shift causes wavelength mismatch, the optical field cannot be effectively coupled, and |CD| drops sharply to 0.0198, resulting in an output of 0.

[0139] When the input is (1,0), the increase in the Fermi level introduces additional losses and changes in the refractive index, which causes the original resonance mode to be suppressed or redshifted. |CD| is 0.057, and the output is 0.

[0140] When the input is (1,1), the resonance peak redshifts and matches the new incident wavelength (1241.9 nm), the resonance intensity is restored, |CD| rises back to 0.96, and the output is 1.

[0141] The above results show that the output is high if and only if the two input logic states are the same, thus accurately implementing the XNOR logic function.

[0142] Furthermore, taking the long wavelength band as an example, the corresponding logic IN when the incident light wavelength is 1267.1 nm B1 =0, corresponding to logic IN when the incident light wavelength is 1267.6 nm. B1 =1. Using the negative CD response, when the input is (0,0), |CD| is 0.69, and when the input is (1,1), |CD| is 0.70), a stable XNOR operation is also achieved. The true values ​​of the operation are shown in Table 2.

[0143] Table 2 Truth Table of Long-Wavelength Chiral Logic Gates

[0144] By combining examples of short-wavelength and long-wavelength bands, the universality and stability of the above-mentioned technical solution provided in this embodiment in the field of on-chip reconfigurable optical computing are illustrated.

[0145] This embodiment achieves dynamic inversion of the CD sign by electrically controlling the Fermi level of graphene, for example, switching it between 0.48 eV and 0.50 eV, and utilizing the high sensitivity of the high-Q quasi-continuous domain bound states to the dielectric constant of graphene. A multi-dimensional dynamically tunable XNOR logic operation is constructed through a dual-input mode of graphene Fermi level modulation and incident wavelength modulation.

[0146] It should be noted that the term "comprising" and its variations used in the embodiments of this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "a plurality" mentioned in the embodiments of this invention are illustrative and not restrictive, and those skilled in the art should understand that unless explicitly indicated otherwise in the context, they should be understood as "one or more". The descriptions of terms such as "first", "second", etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features.

[0147] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the embodiments of this invention are all information and data authorized by the user or fully authorized by all parties.

[0148] The steps described in the method embodiments provided by the present invention can be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of protection of the present invention is not limited in this respect.

[0149] The term "embodiment" in this specification refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily imply the same embodiment, nor does it imply independence or alternativeity from other embodiments. The various embodiments in this specification are described in a related manner, with reference to each other for similar or identical parts. In particular, for apparatus, device, and system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, and relevant details are referred to in the description of the method embodiments.

[0150] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for manufacturing a chiral metasurface device, characterized in that, include: Provide an optical substrate; A silicon functional layer of target thickness is fabricated on the optical substrate; The silicon functional layer is etched to prepare a metasurface structure to obtain a first intermediate product. The metasurface structure includes a plurality of periodically arranged square cells. Each cell is penetrated by a concentric first C-shaped aperture and a second C-shaped aperture. The outer radius of the first C-shaped aperture is smaller than the inner radius of the second C-shaped aperture. The plane containing the axis of symmetry of the first C-shaped aperture is perpendicular to the plane containing the axis of symmetry of the second C-shaped aperture. A graphene layer is prepared on the surface of the silicon functional layer of the first intermediate product to obtain the second intermediate product; Metal electrodes are fabricated on the graphene layer surface of the second intermediate product to obtain a chiral metasurface device.

2. The manufacturing method according to claim 1, characterized in that, Before etching the silicon functional layer to prepare a metasurface structure and obtaining the first intermediate product, the method further includes: Finite element simulation analysis was performed, and the quantitative relationship between the quality factor of the first intermediate product and the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture was determined by data fitting. Based on the target quality factor and the quantitative relationship, the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture are determined for the preparation of the metasurface structure.

3. The manufacturing method according to claim 2, characterized in that, Finite element simulation analysis was performed, and the quantitative relationship between the quality factor of the first intermediate product and the first opening angle of the first C-type aperture and the second opening angle of the second C-type aperture was determined through data fitting, including: Transmission spectral simulation and circular dichroism spectral simulation were performed to obtain spectral simulation results; The coupled-mode equations were established, and the analytical solution for the transmission coefficient was derived. The quantitative relationship is determined by fitting the spectral simulation results and the analytical solution of the transmission coefficient.

4. The manufacturing method according to claim 3, characterized in that, The calculation formulas used for circular dichroism spectrum simulation include: ； In the formula, Represents circular dichroism. This represents the transmission coefficient, indicating that both the transmitted and incident light are right-handed circularly polarized. This represents the transmission coefficient when the transmitted light is left-handed circularly polarized and the incident light is right-handed circularly polarized. This represents the transmission coefficient when the incident light is left-handed circularly polarized and the transmitted light is right-handed circularly polarized. This represents the transmission coefficient, indicating that both the transmitted and incident light are left-handed circularly polarized.

5. The manufacturing method according to claim 1, characterized in that, Before fabricating a silicon functional layer of the target thickness on the optical substrate, the method further includes: The target thickness of the silicon functional layer is determined based on performance requirements; The performance conditions include at least support for Mie resonance in the near-infrared band.

6. The manufacturing method according to claim 5, characterized in that, Before providing an optical substrate, the method further includes: determining the thickness and refractive index of the optical substrate based on a target thickness of the silicon functional layer.

7. A method for controlling a chiral metasurface device, characterized in that, The chiral metasurface device is manufactured according to the manufacturing method of any one of claims 1 to 6, and the control method includes: A control voltage is applied to the metal electrode; The Fermi level of the graphene layer is adjusted based on the control voltage, thereby changing the dielectric constant of the graphene layer and controlling the circular dichroism sign of the chiral metasurface device.

8. The control method according to claim 7, characterized in that, The Fermi level of the graphene layer is adjusted based on the control voltage to change the dielectric constant of the graphene layer. The formulas used include: ； ； In the formula, This indicates the surface electrical conductivity of the graphene layer. Indicates the contribution of in-band factors. The band-to-band factor contribution is represented by i, the imaginary unit, e, and k. B This represents the Boltzmann constant, and T represents the Kelvin temperature. Let E represent the reduced Planck constant, ω represent the incident light frequency, τ represent the momentum relaxation time, and E represent the time of light reduction. f Represents the Fermi level, ε g ε0 represents the relative permittivity tensor of the graphene layer, ε0 represents the vacuum permittivity, and h0 represents the thickness of the graphene layer.

9. The control method according to claim 7, characterized in that, The chiral metasurface device is used to construct an optical XOR logic gate, and the control method further includes: The first input state is determined based on the magnitude of the Fermi level; The second input state is determined based on the magnitude of the incident light wavelength; Based on the first input state and the second input state, and combined with the preset logic output criteria, the output result of the optical XOR logic gate is determined.

10. The control method according to claim 9, characterized in that, The logical output criteria include: When the circular dichroism amplitude of the chiral metasurface device is greater than 0.5, the output is 1; If the amplitude of the circular dichroism is less than or equal to 0.5, output 0; The amplitude of the circular dichroism is related to the size of the Fermi level and the wavelength of the incident light.

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