Unit structure based on coupling effect, metasurface device and design and processing method

Abstract

The invention provides a coupling effect-based unit structure, a metasurface device and a design and processing method, which can be applied to the technical field of metasurfaces. The unit structure comprises a metal layer, a dielectric isolation layer and a resonance layer which are sequentially arranged in the z-axis direction, the resonance layer comprises two adjacent metal resonators in the x-axis direction or the y-axis direction, the two metal resonators are the same in shape and size, and each metal resonator is in a ring shape with a notch. The unit structure is configured to change the coupling effect between the two metal resonators, so that electromagnetic waves vertically incident on the unit structure are reflected outwards from the unit structure at different amplitudes and phases.

Description

Technical Field

[0001] The present disclosure relates to the field of metasurface technology, and more specifically, to a unit structure, a metasurface device, a design, and a processing method based on a coupling effect. Background Art

[0002] Optical devices in related technologies are mainly composed of natural materials, and their performance is usually limited by the properties of the materials themselves and their large size, making them unsuitable for application in integrated devices. In contrast, structures designed with two-dimensional artificial subwavelength metamaterials have unique electromagnetic properties and can be used to design electromagnetic space and efficiently and flexibly control electromagnetic waves. At present, many planar ultra-thin devices have been designed through the ingenious design of metamaterials, such as anomalous deflectors, focusing lenses, special beam generators, polarimeters, invisibility cloaks, etc., challenging the limits of our understanding of the electromagnetic response of natural materials.

[0003] In the process of realizing the concept of the present disclosure, the inventors found that there are at least the following problems in the related art: the unit structure in the related art has limitations in regulating electromagnetic waves and has low efficiency. Summary of the invention

[0004] In view of this, the present disclosure provides a unit structure, a metasurface device, a design and a processing method based on a coupling effect.

[0005] One aspect of the present disclosure provides a unit structure based on a coupling effect, comprising:

[0006] A metal layer, a dielectric isolation layer and a resonance layer are sequentially arranged in the z-axis direction, the resonance layer includes two metal resonators adjacent to each other in the x-axis direction or in the y-axis direction, the two metal resonators have the same shape and size, each of the metal resonators is a ring with a notch, and the unit structure is constructed so that an electromagnetic wave vertically incident on the unit structure is reflected outward from the unit structure with different amplitudes and phases by changing the coupling effect between the two metal resonators.

[0007] According to an embodiment of the present disclosure, the unit structure has a reflection amplitude adjustment range of 0 to 0.8 for the electromagnetic wave vertically incident on the unit structure.

[0008] According to an embodiment of the present disclosure, the reflection phase adjustment range of the unit structure to the electromagnetic wave vertically incident on the unit structure is 0~2π.

[0009] Another aspect of the present disclosure provides a metasurface device based on coupling effect, comprising:

[0010] A plurality of unit structures as described above are distributed in a matrix within a plane determined by the xy axis, so that the metasurface device can achieve single-order diffraction or multi-order diffraction function.

[0011] According to an embodiment of the present disclosure, the material of the dielectric isolation layer is cycloolefin copolymer, and the thickness of the dielectric isolation layer is 48-52 microns.

[0012] According to an embodiment of the present disclosure, the material of the above-mentioned metal resonator is aluminum, the thickness of the above-mentioned metal resonator is 0.18~0.22 microns, the outer ring radius of the above-mentioned metal resonator is 22~24 microns, the ring width of the above-mentioned metal resonator is 0.75~0.85 microns, and the notch width of the above-mentioned metal resonator is 9.5~10.5 microns.

[0013] According to an embodiment of the present disclosure, the material of the metal layer is aluminum, and the thickness of the metal layer is 0.18-0.22 microns.

[0014] Another aspect of the present disclosure provides a design method of a metasurface device based on coupling effect as described above, comprising:

[0015] Determine the number of unit structures in the metasurface device in the x-axis direction or the y-axis direction, wherein the unit structure includes a metal layer, a dielectric isolation layer and a resonance layer sequentially arranged in the z-axis direction, and the resonance layer includes two metal resonators adjacent to each other in the x-axis direction or the y-axis direction, the two metal resonators have the same shape and size, and each of the metal resonators is a ring with a notch;

[0016] According to the single-order diffraction or multi-order diffraction function to be realized by the metasurface device, determining the amplitude and phase of each of the unit structures at a corresponding position in the metasurface device;

[0017] According to the amplitude and phase of each of the unit structures in the metasurface device, determine the azimuth angle of the two metal resonators of each of the unit structures from the amplitude-phase database, wherein the azimuth angle is the angle of the notch of the metal resonator relative to the negative half axis of the y-axis;

[0018] The above-mentioned metasurface device is obtained according to the azimuth angles of the two above-mentioned metal resonators of each above-mentioned unit structure.

[0019] According to an embodiment of the present disclosure, the above method further includes:

[0020] When the azimuth angles of the two metal resonators in the unit structure are at different angles, an electromagnetic simulation is performed on the unit structure to obtain the amplitude and phase of the electromagnetic wave incident on the unit structure along the z-axis and reflected outward in the unit structure;

[0021] An amplitude-phase database is established based on the correspondence between different azimuth angles of the two metal resonators in the unit structure and the reflection amplitude and phase of the electromagnetic wave.

[0022] Another aspect of the present disclosure provides a method for processing the above-mentioned metasurface device, comprising:

[0023] affixing a dielectric isolation layer to the substrate;

[0024] uniformly coating photoresist on the front side of the dielectric isolation layer;

[0025] Using a photolithography machine to expose the dielectric isolation layer, transferring the pattern information on the mask to the photoresist;

[0026] Using a developer to develop the photoresist to preliminarily obtain a target pattern on the photoresist, wherein the target pattern is a plurality of ring-shaped metal resonators with gaps, and the plurality of metal resonators have the same shape and size;

[0027] Performing vacuum thermal evaporation on the developed photoresist to form a metal film;

[0028] removing the photoresist outside the target pattern by using an acetone solution to form a resonance layer;

[0029] Vacuum thermal evaporation is performed on the back side of the dielectric isolation layer to form a metal layer.

[0030] According to the embodiments of the present disclosure, the unit structure of the present disclosure is a metal-insulator-metal (MIM) reflective coupling system model, the upper layer is a double C-shaped ring metal resonator, the middle is a dielectric isolation layer, and the lower layer is a metal layer, which constitutes a Fabry-Perot resonant cavity. The reflection properties of the entire system are the result of multiple interferences of the transflective response of the upper layer and the reflection effect of the bottom layer. Compared with the efficiency limitation of the transmissive single-layer metal metasurface, the MIM structure can achieve efficient wavefront control. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0032] Figure 1 A schematic diagram of a unit structure based on a coupling effect according to an embodiment of the present disclosure is schematically shown;

[0033] Figure 2 A schematic diagram of a metasurface device based on coupling effect according to an embodiment of the present disclosure is schematically shown;

[0034] Figure 3A flow chart schematically shows a method for designing a metasurface device based on coupling effect according to an embodiment of the present disclosure;

[0035] Figure 4 The schematic diagram shows the reflection amplitude and phase of the co-polarization and cross-polarization directions of the unit structure based on the coupling effect according to the embodiment of the present disclosure under the normal incidence of the y-polarization electromagnetic wave with the azimuth angle of the two metal resonators. and Variations in simulation results;

[0036] Figure 5 The schematic diagram shows the reflection amplitude and phase of the co-polarization and cross-polarization directions of the unit structure based on the coupling effect according to the embodiment of the present disclosure under the normal incidence of the y-polarization electromagnetic wave with the azimuth angle of the two metal resonators. and Variations in simulation results;

[0037] Figure 6 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the same polarization direction of the first-order (m=-1) diffraction metasurface grating under the normal incidence of y-polarized electromagnetic waves at 1 THz for the metasurface device based on the coupling effect according to an embodiment of the present disclosure;

[0038] Figure 7 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the same polarization direction of the second-order (m=-2) diffraction metasurface grating under the normal incidence of y-polarized electromagnetic waves at 1 THz for the metasurface device based on the coupling effect according to an embodiment of the present disclosure;

[0039] Figure 8 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the same polarization direction of the first and second order (m=-1, -2) diffraction metasurface gratings of the coupling effect metasurface device according to the embodiment of the present disclosure at 1 THz under the normal incidence of y-polarized electromagnetic waves;

[0040] Fig. 9 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the cross-polarization direction of the first-order (m=-1) diffraction metasurface grating of the coupling effect metasurface device according to the embodiment of the present disclosure at 1 THz under the normal incidence of the y-polarized electromagnetic wave;

[0041] Fig.10 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the cross-polarization direction of the second-order (m=-2) diffraction metasurface grating under the normal incidence of the y-polarized electromagnetic wave at 1 THz for the metasurface device based on the coupling effect according to the embodiment of the present disclosure;

[0042] Fig.11The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the cross-polarization direction of the first- and second-order (m=-1, -2) diffraction metasurface gratings of the coupling effect-based metasurface device according to the embodiment of the present disclosure at 1 THz under the normal incidence of y-polarized electromagnetic waves;

[0043] Fig. 12A A flowchart schematically shows a method for processing a metasurface device according to an embodiment of the present disclosure;

[0044] Fig. 12B A schematic diagram of a processing method of a metasurface device based on coupling effect according to an embodiment of the present disclosure is schematically shown;

[0045] Fig.13 A schematic diagram of an experimental test system of a metasurface device based on coupling effect according to an embodiment of the present disclosure is schematically shown;

[0046] Fig.14 The schematic diagram shows the experimental results of the reflected electric field intensity in the co-polarization and cross-polarization directions of the metasurface gratings of different diffraction orders under the normal incidence of y-polarized electromagnetic waves according to the coupling effect-based metasurface device of the embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0048] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0049] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0050] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0051] In the embodiments of the present disclosure, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage, etc. of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information and network security.

[0052] In the embodiments of the present disclosure, the user's authorization or consent is obtained before obtaining or collecting the user's personal information.

[0053] In metasurface structures, the coupling effect between structures can strongly change the eigenstate of the original resonant system, causing energy to be redistributed between structures, resulting in unique optical responses. The coupling effect between structures promotes many interesting physical phenomena, such as electromagnetically induced transparency, Fano resonance, bound states in the continuous spectrum, etc. These phenomena have been widely used in light modulation, sensing, microwave engineering, nonlinear optics and nanophotonics. However, so far, the application of coupling effects between structures in wavefront control is still rare, which may be due to the fact that most coupling effects are applied to single-layer metal metasurfaces, and in order to achieve a phase that can cover the entire 2π range to control the wavefront of the electromagnetic wave, it is necessary to observe the transmitted electromagnetic wave in the cross-polarization direction, which is very inefficient.

[0054] Due to the resonance effect of the metasurface structure, it can suddenly and locally adjust the amplitude, phase and polarization of the electromagnetic wave, and can achieve almost arbitrary wavefront control. However, in order to achieve the above functions, it is usually necessary to go through a lot of experiments to design a set of structures with different shapes or different geometric parameters to match the expected values. These structures can simultaneously control the amplitude and phase of the output electromagnetic wave within a specific frequency range. While controlling the amplitude of the electromagnetic wave, the phase covers the entire 2π range. The geometric phase method can avoid the situation of designing different shapes and geometric parameters. The purpose of phase coverage range of 2π can be achieved only by rotating the unit structure, but it is only suitable for circularly polarized incidence and cannot control the amplitude of the electromagnetic wave at the same time, which has certain limitations.

[0055] MIM metasurfaces can manipulate the propagation of light in an efficient and flexible manner. This structure enables it to exhibit unique properties in applications such as polarization control, perfect absorption, electrical coding, focusing, and surface plasmons. The design of MIM metasurfaces in related technologies has the following problems: the unit structure of the metasurface that regulates the wavefront of electromagnetic waves needs to be designed with different shapes or different geometric parameters, and it is very complicated to obtain the required amplitude and phase values ​​through these adjustments; without changing the unit structure parameters, only by rotating the unit structure to achieve the purpose of covering the phase regulation range to 2π, it is only suitable for circularly polarized incidence, and cannot simultaneously control the amplitude of electromagnetic waves, which has certain limitations; the metasurface based on the coupling effect only achieves regulation of the phase of electromagnetic waves, and cannot achieve simultaneous regulation of the amplitude and phase of electromagnetic waves under the incidence of linearly polarized electromagnetic waves.

[0056] In view of this, an embodiment of the present disclosure provides a unit structure based on a coupling effect, comprising: a metal layer, a dielectric isolation layer and a resonance layer arranged in sequence in the z-axis direction, the resonance layer comprising two metal resonators adjacent to each other in the x-axis direction or in the y-axis direction, the two metal resonators having the same shape and size, and each metal resonator being a ring with a notch. The unit structure is configured to change the coupling effect between the two metal resonators so that an electromagnetic wave vertically incident on the unit structure is reflected outward from the unit structure with different amplitudes and phases.

[0057] Figure 1 A schematic plan view of a unit structure based on a coupling effect according to an embodiment of the present disclosure is schematically shown.

[0058] like Figure 1 As shown, Figure 1 Figure a is a schematic cross-sectional view of the unit structure along the z axis based on the coupling effect. Figure 1 FIG. 1( b ) is a top view of the unit structure based on the coupling effect in the plane determined by the xy axis.

[0059] like Figure 1 As shown, the unit structure 100 based on the coupling effect includes a metal layer 110, a dielectric isolation layer 120 and a resonance layer 130 arranged in sequence in the z-axis direction, and the resonance layer 130 includes two metal resonators 131 adjacent to each other in the x-axis direction or in the y-axis direction, and the two metal resonators have the same shape and size, and each metal resonator 131 is a ring with a notch. The unit structure 100 is configured to change the coupling effect between the resonators by changing the azimuth angle of the two metal resonators 131, so that the electromagnetic wave vertically incident on the unit structure 100 is reflected outward from the unit structure 100 with different amplitudes and phases.

[0060] According to an embodiment of the present disclosure, the unit structure is composed of a metal layer, a dielectric isolation layer, and a resonant layer to construct a MIM reflective coupling system model. Among them, the resonant layer includes two C-shaped ring metal resonators adjacent to each other in the x-axis direction or in the y-axis direction, and the two C-shaped ring metal resonators have the same shape and size. The unit structure can be regarded as a Fabry-Perot resonant cavity, and its reflection properties are the result of multiple interferences of the transflection response of the upper layer and the reflection effect of the bottom layer. The two C-shaped metal resonators used in the present disclosure have exactly the same structure and are close to each other. They can be rotated at any angle along the z-axis around their respective geometric centers, and the geometric centers of the two metal resonators are on the same vertical line.

[0061] When a linearly polarized electromagnetic wave is incident on the surface of the MIM unit structure, the polarization component of the electromagnetic wave parallel to the resonance direction of the C-shaped ring metal resonator will excite the metal resonator. When the two C-shaped ring metal resonators are close to each other, a coupling effect will occur between the two C-shaped ring metal resonators, and energy will be transferred, so that the electromagnetic wave energy is redistributed between the two metal resonators, resulting in a change in the total reflected energy. Under the premise that the geometric shape and structural dimensions of the two C-shaped ring metal resonators remain unchanged, the coupling effect between the two resonators will be changed by arbitrarily changing the azimuth angles of the two C-shaped ring metal resonators, resulting in changes in the reflected amplitude and phase of the electromagnetic wave near the resonance frequency point. At a certain specific frequency point, the reflection amplitude and phase distribution of the two C-shaped ring metal resonators in the co-polarization and cross-polarization directions corresponding to different azimuth angles can be obtained, and an amplitude phase database can be established.

[0062] Figure 2 A schematic diagram of a metasurface device based on coupling effect according to an embodiment of the present disclosure is schematically shown.

[0063] like Figure 2 As shown, the metasurface device 200 based on the coupling effect includes:

[0064] A plurality of unit structures 210 of the embodiments of the present disclosure are distributed in a matrix within a plane determined by the xy axis, so that the metasurface device can control the wavefront of the electromagnetic wave and produce single-order or multi-order diffraction.

[0065] According to an embodiment of the present disclosure, a plurality of unit structures are arranged periodically to form a metasurface device. Figure 3 Describe the metasurface device.

[0066] Figure 3 A flow chart of a method for designing a metasurface device based on coupling effect according to an embodiment of the present disclosure is schematically shown.

[0067] like Figure 3As shown, the design method of the metasurface device based on the coupling effect includes operations S310 to S340, including:

[0068] In operation S310, the number of unit structures in the metasurface device in the x-axis direction or the y-axis direction is determined, wherein the unit structure includes a metal layer, a dielectric isolation layer, and a resonance layer arranged in sequence in the z-axis direction, and the resonance layer includes two adjacent metal resonators in the x-axis direction or in the y-axis direction, the two metal resonators have the same shape and size, and each metal resonator is a ring with a notch.

[0069] In operation S320, the amplitude and phase of each unit structure at a corresponding position in the metasurface device are determined according to a single-order diffraction or multi-order diffraction function to be implemented by the metasurface device.

[0070] In operation S330, the azimuth angle of two metal resonators of each unit structure is determined from the amplitude-phase database according to the amplitude and phase of each unit structure in the metasurface device, wherein the azimuth angle is the angle of the notch of the metal resonator relative to the negative half axis of the y-axis.

[0071] In operation S340, a metasurface device is obtained according to the azimuth angles of two metal resonators of each unit structure.

[0072] According to an embodiment of the present disclosure, the above method also includes: performing electromagnetic simulation on the unit structure when the azimuth angles of the two metal resonators in the unit structure are at different angles, and obtaining the amplitude and phase of the electromagnetic wave incident on the unit structure along the z-axis and reflected outward in the unit structure; establishing an amplitude phase database according to the correspondence between the different azimuth angles of the two metal resonators in the unit structure and the reflected amplitude and phase of the electromagnetic wave.

[0073] The unit structure can be simulated electromagnetically by simulation software, and the period of the unit structure in the x-axis direction is set to , the period in the y-axis direction is , the thickness of the two C-ring metal resonators , Outer ring radius , Metal line width , opening angle , azimuth and , metal layer thickness , dielectric isolation layer thickness . For the metasurface device based on coupling effect in the present disclosure, the influence of the change of coupling effect between metal resonators on the amplitude and phase of the electromagnetic wave incident to the MIM type unit structure is considered, and the metasurface device of the embodiment of the present disclosure is proposed. The two C-shaped ring metal resonators can only be excited by the polarization component of the electromagnetic wave parallel to their resonance direction. When the polarization direction of the incident electromagnetic wave is perpendicular to the resonance direction of the metal resonator, the two metal resonators will not have a resonant response.

[0074] According to the reflection amplitude and phase results of the two metal resonators in the co-polarization and cross-polarization directions at different azimuth angles, a complete amplitude phase database is established. After the amplitude phase database is established, the grating design is carried out in the x-axis direction, and the grating is arranged periodically in the x-axis and y-axis directions as a super unit to form a metasurface grating device. Along the x-axis direction, the amplitude and phase distribution at the location of each unit structure in the grating can be expressed by the following formula:

[0075] (1)

[0076] in, and represent the amplitude and phase of each unit structure in the grating along the x-axis direction, express The amplitude of the order diffraction, Indicates the position coordinates corresponding to each unit structure that makes up the grating along the x-axis direction, Represents the grating period along the x-axis. Calculate the position of each unit structure in the grating After the corresponding amplitude and phase are obtained, the unit structure is selected from the obtained amplitude and phase database so that the error formula Minimum, among which and They represent the amplitude and phase corresponding to the simulated unit structure, and They represent the amplitude and phase calculated by formula (1) respectively. The selected unit structures are arranged in sequence along the x-axis direction to obtain a grating. The grating is arranged periodically along the x-axis and y-axis directions as a super unit to obtain a metasurface grating device. When a linearly polarized electromagnetic wave is incident on the metasurface device, the metasurface device can deflect the beam according to the designed diffraction order to achieve control of the electromagnetic wave wavefront.

[0077] According to the embodiment of the present disclosure, the amplitude phase database is established as follows: when the electromagnetic wave is incident on the unit structure, the coupling effect between the metal resonators is adjusted by rotating the azimuth angles of the two C-shaped ring metal resonators in the unit structure, and the electromagnetic wave energy is redistributed between the two metal resonators, resulting in changes in the amplitude and phase of the electromagnetic wave reflected by the unit structure. The two C-shaped ring metal resonators are rotated around their respective geometric centers along the z-axis, and the angles between the azimuth angles and the negative half axis of the y-axis are respectively and , under normal incidence of y-polarized electromagnetic wave, the coupling model of the unit structure is described as:

[0078] (2)

[0079] (3)

[0080] in ( )、 ( )、 ( )and ( ) represent the complex amplitude, resonant frequency, radiation loss and absorption loss of the metal resonator 1 (2) respectively; is the coupling coefficient between the two metal resonators; ( ) is the projection of the polarization direction of the electromagnetic wave on the resonance direction of the metal resonator. The 1 / 2 in equations (2) and (3) represents the energy of the incident field that each of the two C-shaped ring metal resonators in a unit structure accounts for The reflection coefficients in the y-polarization direction and the x-polarization direction are:

[0081] (4)

[0082] (5)

[0083] Since the structures of the two metal resonators are exactly the same, they have the same properties, and we can get , , , the theoretical model is further simplified. By solving the above equations, we can get:

[0084] (6)

[0085] (7)

[0086] (8)

[0087] (9)

[0088] It can be seen from formulas (8) and (9) that the resonant frequency of the metal resonator , radiation loss and absorption loss When the two metal resonators are fixed, only the azimuth angles of the two metal resonators are changed. and To adjust the coupling coefficient The reflection coefficients of the co-polarization and cross-polarization directions of the entire unit system can be changed, and the reflection amplitude and phase can be obtained.

[0089] According to the embodiments of the present disclosure, the present disclosure introduces the coupling between metal resonators into the metasurface device, and establishes a new dual-resonance unit coupling system. Without changing the geometric shape and structural size of the unit structure, the reflection amplitude and phase of the unit structure can be changed by simply changing the azimuth angle of the two C-shaped ring metal resonators to adjust the coupling effect between the resonators, thereby establishing a complete amplitude-phase database. The established amplitude-phase database can be used to design the required metasurface device to achieve the regulation of the electromagnetic wave front.

[0090] Compared with the related art, the present disclosure has the following advantages: the unit structure in the coupling effect-based metasurface device of the present disclosure is a reflective coupling system model, and the upper layer is a resonant layer, the middle layer is a dielectric isolation layer, and the lower layer is a metal layer. The MIM-type structure constitutes a Fabry-Perot resonant cavity. Among them, the resonant layer includes two C-shaped ring metal resonators adjacent to each other in the x-axis direction or in the y-axis direction, and the two C-shaped ring metal resonators have the same shape and size. The reflection properties of the entire system are the result of multiple interferences of the transmissive reflection response of the upper layer and the reflection effect of the bottom layer. Compared with the efficiency limitation of the transmissive single-layer metal metasurface, the MIM-type structure can achieve efficient wavefront control.

[0091] The coupling-effect-based metasurface device disclosed in the present invention constructs a reflective coupling system model consisting of two C-shaped ring metal resonators of the same geometric shape and structural size through coupled mode theory. Without changing the geometric shape and structural size of the resonator, the coupling effect is changed by changing the azimuth angle of the C-shaped ring metal resonator, so that the reflection amplitude and phase of the unit structure near the resonance frequency can be changed, and a complete amplitude-phase database can be established to achieve modulation of the optical properties of the system.

[0092] The coupling effect-based metasurface device disclosed in the present invention only rotates the azimuth angles of two C-shaped ring metal resonators in the unit structure. Under normal incidence of linearly polarized electromagnetic waves, near the resonance frequency point, the reflection amplitudes in the co-polarization and cross-polarization directions can be continuously adjusted in the range of 0-0.8, and the phase can be continuously controlled in the range of -π~-π, thereby improving the design freedom.

[0093] The coupling-effect-based metasurface device disclosed in the present invention can break through the various limitations of traditional optical elements and bulk metamaterials, and exhibits powerful wavefront control capabilities. Its ultra-thin and compact nature and the ability to perform point-by-point control of the light field in space on a sub-wavelength scale provide a new design idea for integrated micro-optical components.

[0094] According to an embodiment of the present disclosure, in a metasurface device, the material of the dielectric isolation layer may be cycloolefin copolymer, and the thickness of the dielectric isolation layer is 48 to 52 microns. The thickness of the metal resonator is 0.18 to 0.22 microns, the outer ring radius of the metal resonator is 22 to 24 microns, the ring width of the metal resonator is 0.75 to 0.85 microns, and the gap width of the metal resonator is 9.5 to 10.5 microns. The thickness of the metal layer is 0.18 to 0.22 microns. Among them, the material of the metal resonator and the metal layer is aluminum.

[0095] Based on the above dimensions, a specific design of the unit structure of a metasurface device based on the coupling effect is proposed.

[0096] Electromagnetic simulation software is used to simulate the unit structure of the metasurface device, and the corresponding reflection amplitude and phase are obtained when the two metal resonators are at different azimuth angles. The details are as follows: Set the period of the unit structure in the x-axis direction , the period in the y-axis direction , the thickness of the two C-ring metal resonators , the outer ring radius , metal line width , opening width , metal layer thickness , the two C-shaped ring metal resonators and the metal layer are made of aluminum with a conductivity of 3.56×10 7 S / m, the dielectric isolation layer uses a flexible material cycloolefin copolymer (COC), the dielectric isolation layer thickness Rotating the azimuth angles of the two C-shaped ring metal resonators and , the electromagnetic wave is incident in the y-polarization direction, and the reflection amplitude and phase of the unit structure in the co-polarization and cross-polarization directions are observed. Considering the symmetry of the two C-shaped ring metal resonators in the unit structure relative to the y-axis during rotation, and in order to reduce the amount of calculation, The range is from 0° to 360° in 2° steps. The parameter sweep was simulated over 180 degrees with a step size of 2 degrees from 0 degrees to 180 degrees. 81 sets of data.

[0097] Figure 4 a in the figure shows the reflection amplitude in the same polarization direction when the y-polarized electromagnetic wave is incident on the unit structure at a frequency of 1 THz and changes with the azimuth angle of the two C-shaped ring metal resonators. and Simulation results of the changes. Figure 4 In b, the y-polarized electromagnetic wave is incident on the unit structure. At a frequency of 1 THz, the reflection phase in the same polarization direction varies with the azimuth angle of the two C-shaped ring metal resonators. and Simulation results of the changes. Figure 4 c is the reflection amplitude in the cross-polarization direction when the y-polarized electromagnetic wave is incident on the unit structure and the inverse frequency is 1THz. and Simulation results of the changes. Figure 4 In the figure, d is the reflection phase in the cross-polarization direction of the y-polarized electromagnetic wave incident on the unit structure at a frequency of 1 THz, which varies with the azimuth angle of the two C-shaped ring metal resonators. and The simulation results show that the geometry and structural dimensions of the two C-shaped ring metal resonators in the unit structure remain unchanged, and the coupling effect is adjusted by changing the azimuth angles of the two C-shaped ring metal resonators. Under normal incidence of y-polarized electromagnetic waves, at a frequency of 1 THz, arbitrary modulation of the reflection amplitude of 0-0.8 and the phase of -π~π in the co-polarization and cross-polarization directions can be achieved. Therefore, the unit structure of the embodiment of the present disclosure has a reflection amplitude adjustment range of 0~0.8 for electromagnetic waves vertically incident on the unit structure, and a reflection phase adjustment range of 0~2π for electromagnetic waves vertically incident on the unit structure.

[0098] Figure 5 Schematic diagram showing the reflection amplitude and phase of the unit structure based on the coupling effect according to the embodiment of the present disclosure in the co-polarization and cross-polarization directions under the normal incidence of the y-polarization electromagnetic wave with the azimuth angle of the two metal resonators and Variation of the fitting results.

[0099] Figure 5 a in the figure shows the reflection amplitude in the same polarization direction when the y-polarized electromagnetic wave is incident on the unit structure at a frequency of 1 THz and changes with the azimuth angle of the two C-shaped ring metal resonators. and Variation of the fitting results. Figure 5In b, the y-polarized electromagnetic wave is incident on the unit structure. At a frequency of 1 THz, the reflection phase in the same polarization direction varies with the azimuth angle of the two C-shaped ring metal resonators. and Variation of the fitting results. Figure 5 c is the reflection amplitude in the cross-polarization direction when the y-polarized electromagnetic wave is incident on the unit structure at a frequency of 1 THz and changes with the azimuth angle of the two C-shaped ring metal resonators. and Variation of the fitting results. Figure 5 In the figure, d is the reflection phase in the cross-polarization direction of the y-polarized electromagnetic wave incident on the unit structure at a frequency of 1 THz, which varies with the azimuth angle of the two C-shaped ring metal resonators. and Variation of the fitting results.

[0100] The derived coupled mode formulas (8) and (9) are used to fit the simulated spectrum and extract the reflection amplitude and phase in the co-polarization and cross-polarization directions at a frequency of 1 THz as the azimuth angles of the two C-shaped ring metal resonators change. and Change trend. The resonant frequency of the metal resonator , radiation loss and absorption loss When the two metal resonators are fixed, only the azimuth angles of the two metal resonators are changed. and To adjust the coupling coefficient The reflection coefficients of the entire unit system in the co-polarization and cross-polarization directions can be obtained. and The results of the change in the coupling mode formula show that the corresponding fitting results obtained by the coupled mode formula are basically consistent with the simulation results. Therefore, the above fitting results further prove that by simply modifying the azimuth angle of the two metal resonators and , the internal coupling effect of the two metal resonators can be adjusted, so that without changing the geometric shape and structural size of the two metal resonators, the reflection amplitude of the electromagnetic waves in the co-polarization and cross-polarization directions can be arbitrarily modulated from 0 to 0.8 and the phase from 0 to 2π, respectively. This function increases the freedom and flexibility of the design of metasurface devices.

[0101] Design of metasurface devices based on the principle of generalized Snell's law: ,in is the wavelength in vacuum, represents the refractive index of the propagation space medium, is the incident angle, is the reflection angle, is the phase gradient. When an electromagnetic wave passes through the interface of different media, the propagation path of the outgoing electromagnetic wave can be determined by the phase mutation amount of the interface, and the phase mutation amount at the interface is used to compensate for the phase difference between different paths. On this basis, a single-order and multi-order diffraction grating composed of 8 unit structures is designed in the x-axis direction. The grating is used as a super unit and periodically arranged in the x-axis and y-axis directions to obtain a metasurface grating device. Under the normal incidence of y-polarized electromagnetic waves, abnormal deflection of electromagnetic wave beams can be achieved in the co-polarized and cross-polarized reflection directions. The amplitude and phase distribution corresponding to each unit structure in the grating is given by Get (where, Represents the grating The amplitude of the order diffraction, is the grating period along the x-direction):

[0102] First, a first-order diffraction metasurface grating (m = -1) with the same polarization direction is designed along the x-direction. The entire grating consists of 8 unit structures arranged in sequence along the x-axis, and the phase gradient is ,Right now According to formula (1), the position of each unit structure of the grating is calculated: The corresponding amplitude and phase. From the obtained amplitude and phase database, select the corresponding unit structure so that the error formula Minimum. Arrange the selected unit structures in sequence along the x-axis direction to obtain a grating, and arrange the grating as a super unit periodically in the x-axis and y-axis directions to obtain a metasurface grating device. When the y-polarized terahertz electromagnetic wave is incident on the metasurface device, the metasurface device can deflect the electromagnetic wave according to the designed first-order diffraction angle.

[0103] Figure 6 The simulation results and diffraction order information of the reflected electric field distribution in the same polarization direction of the first-order (m=-1) diffraction metasurface grating of the coupling effect-based metasurface device according to an embodiment of the present disclosure at 1 THz under normal incidence of y-polarized electromagnetic waves are schematically shown.

[0104] Figure 6 Figure a is the simulation result of the reflected electric field distribution in the same polarization direction of the designed first-order (m=-1) diffraction metasurface grating under normal incidence of y-polarized electromagnetic wave. The smooth and inclined wavefront can be clearly observed from the figure, realizing the function of abnormal deflection of electromagnetic waves. Figure 6 In b, the field distribution extracted along the x-axis at a distance of 300 μm from the metasurface device is retrieved after Fourier transformation. The horizontal axis represents the diffraction order, and the vertical axis represents the diffraction efficiency. The simulated diffraction angle θ is 24.7°, which is consistent with the generalized Snell's law. The calculated theoretical value of 24.6° is very consistent, and the diffraction efficiency at the designed deflection angle is 74.36%. The same method can be used to design second-order diffraction metasurface gratings (θ = 56.4°) and first- and second-order multi-order diffraction metasurface gratings, such as Figure 7~Figure 11 .

[0105] in, Figure 7 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the same polarization direction of the second-order (m=-2) diffraction metasurface grating of the metasurface device based on the coupling effect according to the embodiment of the present disclosure at 1 THz under the normal incidence of the y-polarized electromagnetic wave. The simulated calculated diffraction angle θ is 56.0°, which is consistent with the generalized Snell's law. The calculated theoretical value of 56.4° is very consistent, and the diffraction efficiency at the designed deflection angle is 72.05%.

[0106] Figure 8 The diagram schematically shows the simulation results and diffraction order information of the reflected electric field distribution in the same polarization direction of the first and second order (m=-1, -2) diffraction metasurface gratings of the coupling effect-based metasurface device according to an embodiment of the present disclosure at 1 THz under normal incidence of y-polarized electromagnetic waves.

[0107] Fig. 9 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the cross-polarization direction of the first-order (m=-1) diffraction metasurface grating of the metasurface device based on the coupling effect according to the embodiment of the present disclosure at 1 THz under the normal incidence of the y-polarized electromagnetic wave. The simulated calculated diffraction angle θ is 24.7°, which is consistent with the generalized Snell's law. The calculated theoretical value of 24.6° is very consistent, and the diffraction efficiency at the designed deflection angle is 71.40%.

[0108] Fig.10 The schematic diagram shows the simulation results and diffraction order information of the reflected electric field distribution in the cross-polarization direction of the second-order (m=-2) diffraction metasurface grating of the metasurface device based on the coupling effect according to the embodiment of the present disclosure at 1 THz under the normal incidence of the y-polarized electromagnetic wave. The simulated calculated diffraction angle θ is 56.0°, which is consistent with the generalized Snell's law. The calculated theoretical value of 56.4° is very consistent, and the diffraction efficiency at the designed deflection angle is 55.82%.

[0109] Fig.11 The diagram schematically shows the simulation results and diffraction order information of the reflected electric field distribution in the cross-polarization direction of the first and second order (m=-1, -2) diffraction metasurface gratings of the coupling effect-based metasurface device according to an embodiment of the present disclosure at 1 THz under normal incidence of y-polarized electromagnetic waves.

[0110] Figure 8~Figure 11 The simulation results of the reflected electric field distribution corresponding to each metasurface grating and the diffraction order information retrieved after Fourier transform. The electric field distribution of multi-order (first and second order) metasurface gratings is no longer uniform due to the interference between multiple diffraction orders, but the two different designed diffraction orders can be clearly seen from the diffraction order information retrieved after Fourier transform.

[0111] The following is an introduction to the processing method of the metasurface grating device. The size of the functional device in the terahertz band is generally in the micron range, so the sample processing is usually completed using the photolithography technology that has been widely used in semiconductor manufacturing processes. Photolithography technology is a process that combines photographic replication and chemical etching processes to transfer the pre-designed pattern on the mask to the substrate using light of a specific wavelength. In order to reduce the loss of the material to the terahertz wave, the substrate material used in the present disclosure is a cycloolefin hydrogen copolymer.

[0112] Fig. 12A The flowchart of the method for processing a device according to an embodiment of the present disclosure is schematically shown.

[0113] like Fig. 12A As shown, the method includes operations S1210 to S1270.

[0114] In operation S1210, a dielectric isolation layer is pasted on a substrate.

[0115] In operation S1220 , a photoresist is coated on the front side of the dielectric isolation layer.

[0116] In operation S1230, the dielectric isolation layer is exposed using a photolithography machine to transfer the pattern information on the mask to the photoresist.

[0117] In operation S1240, the photoresist is developed using a developer to preliminarily obtain a target pattern on the photoresist, wherein the target pattern is a plurality of ring-shaped metal resonators with gaps, and the plurality of metal resonators have the same shape and size.

[0118] In operation S1250, vacuum thermal evaporation is performed on the developed photoresist to form a metal thin film.

[0119] In operation S1260, the photoresist outside the target pattern is removed using an acetone solution to form a resonance layer.

[0120] In operation S1270, vacuum thermal evaporation is performed on the back side of the dielectric isolation layer to form a metal layer.

[0121] Description of operation S1210 to operation S1270 Fig. 12B Give a description.

[0122] Fig. 12B A schematic diagram of a method for processing a metasurface device based on coupling effect according to an embodiment of the present disclosure is schematically shown.

[0123] like Fig. 12B As shown in the figure, the processing flow chart of metasurface devices can be divided into three major steps, namely, coating, photolithography and evaporation.

[0124] Paste COC film: Use double-sided tape to paste the COC film on the cleaned silicon wafer, tear off the protective film of the COC film, and fix the silicon wafer with the vacuum suction cup of the spin coater. Spread the film: Drop the prepared photoresist on the surface of the COC film. The ideal spread effect can be obtained by setting the various parameters of the spin coater.

[0125] Heating and drying: Place the silicon wafer on a heating plate to dry the photoresist. The purpose is to remove most of the solvent in the photoresist, ensure the stability of the area where the photoresist properties change after the exposure operation, and increase the adhesion of the photoresist.

[0126] Exposure: Exposure is a key step in the entire photolithography process, which realizes the transfer of the processed pattern from the mask to the film. Just put the mask and the film coated with photoresist into the photolithography machine, set the appropriate exposure time according to the performance parameters of the photolithography machine and the properties of the photoresist, and expose. The light-transmitting part of the mask changes the properties of the photoresist in the photosensitive area, leaving graphic information on the COC film.

[0127] Development: Use a developer to develop the photoresist. The photoresist with changed properties will dissolve in the developer, thereby initially obtaining the designed target pattern on the film.

[0128] Evaporation: Use an evaporation machine to evacuate the vacuum first. Heat the metal rod and evaporate it into a gaseous state, thereby depositing the required thin film on the metasurface device. By adjusting the magnitude of the applied current, the evaporation rate of the coating material can be conveniently controlled. Here, the thickness of the metal layer of the metasurface device is set to 200 nm.

[0129] Stripping: Immerse the sample in an acetone solution, and the part with the photoresist under the metal will automatically dissolve and fall off, revealing the target pattern of the metasurface device.

[0130] According to the embodiments of the present disclosure, since the processed metasurface device is a reflective sample, after the front structure is completed, a 200 nm thick metal reflective layer needs to be evaporated on the back of the COC film to complete the processing flow of the metasurface device.

[0131] Fig.13 A schematic diagram of an experimental test system for a metasurface device based on coupling effect according to an embodiment of the present disclosure is shown schematically.

[0132] like Fig.13 As shown in the figure, the metasurface device is used as a sample for testing. Since the function of the designed and processed sample is abnormal angle deflection, it is necessary to measure the reflection characteristics of the sample at different angles when characterizing the experimental effect of the sample. The measurement part of the specific experimental device is shown in the figure. Fig.13 As shown in the figure, an optical fiber-based angle-resolved terahertz time-domain spectroscopy system is used to characterize the reflection characteristics of the sample under normal incidence. The terahertz transmitter and receiver modules are made of photoconductive antennas and terahertz lenses, and the two modules are fixed on a guide rail that can rotate around a rotating table. During the measurement, the position of the transmitting antenna is kept unchanged, and the detection antenna is controlled to scan the reflection characteristics of the sample point by point with a resolution of 1°. A sample with a metal aluminum film on the surface is attached to the sample holder, and the sample holder is installed on the center of the rotating table. The transmitting antenna and the detection antenna fixed on the guide rail are rotated to make the incident angle equal to the reflection angle, and the terahertz signal will be fully reflected. The pitch of the sample holder is adjusted to make the detection signal reach the maximum value, which is used as a reference signal. Then the transmitting antenna is adjusted back to the position when the sample is initially incident normally. After the terahertz wave is emitted from the photoconductive antenna, it is first collimated by the lens and then irradiated on the sample. The terahertz wave is reflected to a specific direction according to the deflection angle designed for the sample. Due to the conflict between the transmitting antenna and the detection antenna in the reflection measurement, the minimum detectable angle is ±20°. In the experiment, 20° to 80° and -20° to -80° were selected as the measurement scanning range, and the rotation state of the detector was gradually moved to obtain the angular resolution reflection characteristics of the sample. The reflected electric field intensity of the designed metasurface device in the co-polarization and cross-polarization directions was measured respectively. The normalized broadband reflectivity of each metasurface device The angle scanning results are as follows: Fig.14 shown.

[0133] Fig.14 The schematic diagram shows the experimental results of the reflected electric field strength in the co-polarization and cross-polarization directions obtained by angular scanning of the metasurface gratings of different diffraction orders under normal incidence of y-polarized electromagnetic waves according to the coupling effect-based metasurface grating device of the embodiment of the present disclosure.

[0134] Fig.14 Figure a is the experimental result of the reflected electric field intensity in the same polarization direction of the first-order (m = -1) diffraction metasurface grating under normal incidence of y-polarized electromagnetic wave. Fig.14 Figure b shows the experimental result of the reflected electric field intensity in the same polarization direction when the second-order (m = -2) diffraction metasurface grating is angularly scanned under normal incidence of y-polarized electromagnetic wave. Fig.14 Figure c is the experimental result of the reflection intensity in the same polarization direction of the first- and second-order (m = -1 and m = -2) diffraction metasurface gratings under normal incidence of y-polarized electromagnetic waves. Fig.14(d) is the experimental result of the reflected electric field intensity in the cross-polarization direction of the first-order (m = -1) diffraction metasurface grating under normal incidence of y-polarized electromagnetic wave. Fig.14 e in the figure is the experimental result of the reflected electric field intensity in the cross-polarization direction of the second-order (m = -2) diffraction metasurface grating under normal incidence of y-polarized electromagnetic wave. Fig.14 f in the figure is the experimental result of the reflected electric field intensity in the cross-polarization direction of the first- and second-order (m = -1 and m = -2) diffraction metasurface gratings under normal incidence of y-polarized electromagnetic waves. From the measurement results, it can be clearly seen that there is an abnormal deflection phenomenon in the 0.8 to 1.2 THz broadband. The white dotted line in the figure is the ideal deflection angle calculated by the generalized Snell's law. It can be found that the experimental results are in good agreement with the theoretical calculation results. The slight angle deviation may be caused by processing errors and sample placement errors during the experiment.

[0135] The present invention introduces the coupling effect between metal resonators into the design of metasurface devices, and establishes a new metasurface device with dual resonance units. Using dual C-shaped ring metal resonators with the same structure as the unit structure, without changing the geometric shape and structural size of the unit structure, the coupling strength between the metal resonators is adjusted by only changing the azimuth angles of the two C-shaped ring metal resonators, thereby changing the amplitude and phase of the electromagnetic wave output near the resonance frequency, providing the ability to control the amplitude and phase of the electromagnetic wave on demand. By establishing a complete amplitude-phase database, the amplitude of the output in the co-polarization direction and the cross-polarization direction can be continuously adjusted in the range of 0-0.8, and the phase can be continuously regulated in the range of -π~π, which improves the design freedom.

[0136] The abnormal beam deflection function demonstrated in this disclosure is only one of many wavefront control functions. By using this method of changing coupling to achieve continuous control of amplitude and phase, many complex and diverse wavefront control devices can be designed. This disclosure is based on the terahertz band for research and can be extended to other bands according to one's own needs.

[0137] The metasurface device proposed in the present disclosure can be used in the fields of light modulation, sensing, deflector, focusing lens, polarimeter, holographic imaging, etc.

[0138] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present disclosure can be combined and / or combined in a variety of ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0139] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A unit structure based on coupling effect, comprising: A metal layer, a dielectric isolation layer and a resonance layer are sequentially arranged in the z-axis direction, the resonance layer includes two metal resonators adjacent to each other in the x-axis direction or in the y-axis direction, the two metal resonators have the same shape and size, each of the metal resonators is a ring with a notch, and the unit structure is constructed so that an electromagnetic wave vertically incident on the unit structure is reflected outward from the unit structure with different amplitudes and phases by changing the coupling effect between the two metal resonators.

2. The unit structure according to claim 1, wherein: The unit structure adjusts the reflection amplitude of the electromagnetic wave vertically incident on the unit structure in a range of 0 to 0.

8.

3. The unit structure according to claim 1, wherein: The unit structure adjusts the reflection phase of the electromagnetic wave vertically incident on the unit structure in a range of 0 to 2π.

4. A metasurface device based on coupling effect, comprising: A plurality of unit structures as described in any one of claims 1 to 3 are distributed in a matrix in a plane determined by the xy axis, so that the metasurface device can realize single-order diffraction or multi-order diffraction function.

5. The device according to claim 4, wherein The dielectric isolation layer is made of cycloolefin copolymer, and the thickness of the dielectric isolation layer is 48-52 microns.

6. The device according to claim 4, wherein The material of the metal resonator is aluminum, the thickness of the metal resonator is 0.18~0.22 microns, the outer ring radius of the metal resonator is 22~24 microns, the ring width of the metal resonator is 0.75~0.85 microns, and the gap width of the metal resonator is 9.5~10.5 microns.

7. The device according to claim 4, wherein The material of the metal layer is aluminum, and the thickness of the metal layer is 0.18-0.22 microns.

8. A method for designing a metasurface device based on coupling effect as claimed in any one of claims 4 to 7, comprising: Determine the number of unit structures in the metasurface device in the x-axis direction or the y-axis direction, wherein the unit structure includes a metal layer, a dielectric isolation layer and a resonance layer sequentially arranged in the z-axis direction, and the resonance layer includes two metal resonators adjacent to each other in the x-axis direction or in the y-axis direction, the two metal resonators have the same shape and size, and each of the metal resonators is a ring with a notch; According to the single-order diffraction or multi-order diffraction function to be realized by the metasurface device, determining the amplitude and phase of each unit structure at a corresponding position in the metasurface device; According to the amplitude and phase of each unit structure in the metasurface device, determine the azimuth angle of the two metal resonators of each unit structure from the amplitude-phase database, wherein the azimuth angle is the angle of the notch of the metal resonator relative to the negative half axis of the y-axis; The metasurface device is obtained according to the azimuth angles of the two metal resonators of each unit structure.

9. The method according to claim 8, further comprising: When the azimuth angles of the two metal resonators in the unit structure are at different angles, performing electromagnetic simulation on the unit structure to obtain the amplitude and phase of the electromagnetic wave incident on the unit structure along the z-axis and reflected outward in the unit structure; The amplitude-phase database is established according to the corresponding relationship between different azimuth angles of the two metal resonators in the unit structure and the reflected amplitude and phase of the electromagnetic wave.

10. A method for preparing a device as claimed in any one of claims 4 to 7, comprising: affixing a dielectric isolation layer to the substrate; uniformly coating photoresist on the front surface of the dielectric isolation layer; Using a photolithography machine to expose the dielectric isolation layer, and transferring the pattern information on the mask to the photoresist; Developing the photoresist with a developer to preliminarily obtain a target pattern on the photoresist, wherein the target pattern is a plurality of ring-shaped metal resonators with gaps, and the plurality of metal resonators have the same shape and size; Performing vacuum thermal evaporation on the developed photoresist to form a metal film; removing the photoresist outside the target pattern by using an acetone solution to form a resonance layer; Vacuum thermal evaporation is performed on the back side of the dielectric isolation layer to form a metal layer.

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