Reconfigurable metasurface device and preparation method and phase compensation method thereof

Abstract

The invention discloses a reconfigurable metasurface device and a preparation method and a phase compensation method thereof. The reconfigurable metasurface device comprises a substrate layer, a metasurface structure layer and a phase compensation layer, wherein the metasurface structure layer and the phase compensation layer are located on the two sides of the substrate layer respectively. Wherein the phase compensation layer is used for performing phase compensation on the metasurface structure layer. According to the phase compensation method for the reconfigurable metasurface device, the phase compensation of the metasurface structure can be realized under the condition of not changing the nano column array of the metasurface structure and the preparation process.

Description

Technical Field

[0001] The present application relates to the field of metasurface technology, and in particular to a reconfigurable metasurface device and a preparation method and a phase compensation method thereof. Background Art

[0002] As a carrier of information transmission, electromagnetic waves are widely used in various fields in the development of modern information technology. In the military field, electromagnetic waves can be used for command operations, intelligence collection, target detection and anti-interference. In the civilian field, electromagnetic waves are widely used in electronic communications, medical treatment, environmental monitoring and home life. It is closely related to our lives and plays an extremely important role in both daily life and military life. Therefore, it is very necessary to achieve effective control of electromagnetic waves, which has become a research hotspot in various fields.

[0003] Metasurfaces are a new type of two-dimensional planar structure composed of subwavelength elements, which provide a promising platform for ultrathin planar optics compared to traditional diffractive optical elements. By changing the size, arrangement and shape of meta-atoms inside the metasurface, the amplitude and phase of light can be controlled simultaneously.

[0004] Diffractive metasurface devices are metasurface optical elements designed based on the principle of diffraction. They introduce specific phase, amplitude or polarization changes in the light wavefront through designed nanostructures, thereby achieving precise manipulation of light waves. These devices are usually used in the fields of beam shaping, wavefront control, optical imaging and spectral analysis. This metasurface is composed of subwavelength-sized microstructure units, which can manipulate the wavefront of light in a specific way, thereby introducing abnormal phase mutations. From the perspective of its unit resonance mode, it can be divided into transmission phase units and geometric phase units. Transmission phase modulation is (propagation phase-reliant metalens, PR-metalens), which refers to the control of the output phase of electromagnetic waves by modulating the accumulated phase of electromagnetic waves after passing through the dielectric metasurface. Geometric phase is also called Pancharatnam–Berry (PB) phase. When the unit of the superlens is an anisotropic nanocolumn, the length and width of the nanocolumn can be regarded as the long axis and the slow axis. This anisotropic structure will produce phase differences along the two main axes. Similar to a wave plate, in the case of circularly polarized light incident, an additional phase related only to the rotation angle can be introduced by adjusting the rotation angle of the anisotropic unit structure on the substrate. By controlling the phase of the light emitted from the metasurface, the established imaging function can be achieved in the far field or near field through the principle of interference superposition of light.

[0005] The phase adjustment of the above-mentioned metasurface to light is mainly determined by the geometric shape and size of the structural unit, as well as the dielectric constant of the material. After the device is prepared, the geometric shape and size of the structure are difficult to change, and the error of the existing processing technology will inevitably produce an error between the designed phase and the actual phase. Therefore, in actual use, there will be a phase difference between the designed phase distribution and the actual phase distribution after the metasurface is processed, resulting in the function of the metasurface not achieving the expected effect. Once the metasurface is processed, the physical structure cannot be changed, so how to perform metasurface phase compensation is particularly important. Summary of the invention

[0006] In order to solve the above-mentioned deficiencies in the art, the present application aims to provide a reconfigurable metasurface device and its preparation method and phase compensation method. Through a reconfigurable metasurface structure, preparation method, compensation method and device, a phase compensation layer is added on the other surface of the substrate relative to the nanopillars, which can adjust the phase distribution of the electromagnetic wave passing through the metasurface structure, thereby adjusting the phase error of the original metasurface.

[0007] According to one aspect of the present application, a reconfigurable metasurface device is provided, comprising: a substrate layer, and a metasurface structure layer and a phase compensation layer respectively located on both sides of the substrate layer;

[0008] The phase compensation layer is used to perform phase compensation on the metasurface structure layer.

[0009] The substrate layer includes a first substrate layer, a substrate spacer layer and a second substrate layer in sequence, the super-surface structure layer is located on the surface of the first substrate layer, and the phase compensation layer is located on the surface of the second substrate layer.

[0010] According to some embodiments of the present application, the phase compensation layer is made of a phase change material.

[0011] According to some embodiments of the present application, the phase change material is composed of Sb single substance, Te single substance and / or sulfur compound phase change material.

[0012] According to some embodiments of the present application, the chalcogenide phase change material includes: germanium antimony telluride, antimony sulfide, antimony selenide, antimony telluride, germanium telluride or germanium antimony selenium telluride compounds;

[0013] According to some embodiments of the present application, the germanium antimony tellurium compound includes one or more of Ge2Sb2Te5, Ge3Sb2Te6, GeSb4Te7 and GeSb2Te4.

[0014] According to another aspect of the present application, a method for preparing a reconfigurable metasurface device is provided, comprising:

[0015] According to the theoretical phase distribution, a super surface structure layer distributed in a periodic array is grown on the first surface of the substrate layer and / or on the surface of the first substrate layer;

[0016] Detecting the actual phase distribution of the metasurface structure layer;

[0017] Obtaining a phase distribution error between an actual phase distribution and a theoretical phase distribution;

[0018] Growing a phase compensation layer on the second surface of the substrate layer and / or the surface of the second substrate layer according to the phase distribution error to obtain a reconfigurable metasurface device;

[0019] Wherein, the phase compensation layer is used to perform phase compensation on the metasurface structure layer.

[0020] According to some embodiments of the present application, growing a phase compensation layer according to the phase distribution error on the second surface of the substrate layer and / or the surface of the second substrate layer includes:

[0021] According to the period of the metasurface structure layer distributed in a periodic array, or according to the phase distribution error, the phase compensation layer is divided into regions to obtain the phase distribution of the phase change material in different regions and obtain the phase library of the phase change material;

[0022] A phase compensation layer is grown on the second surface of the substrate layer and / or on the surface of the second substrate layer according to the phase library and the phase distribution error.

[0023] According to some embodiments of the present application, the phase compensation layer is made of a phase change material.

[0024] According to some embodiments of the present application, the phase change material includes: one or more of Sb single substance, Te single substance and sulfur-based compounds.

[0025] According to some embodiments of the present application, the chalcogenide phase change material includes: germanium antimony telluride, antimony sulfide, antimony selenide, antimony telluride, germanium telluride or germanium antimony selenium telluride compounds;

[0026] According to some embodiments of the present application, the germanium antimony tellurium compound includes one or more of Ge2Sb2Te5, Ge3Sb2Te6, GeSb4Te7 and GeSb2Te4.

[0027] According to another aspect of the present application, a phase compensation method for a reconfigurable metasurface device is also provided, comprising:

[0028] According to the theoretical phase distribution, a super surface structure layer distributed in a periodic array is grown on the first surface of the substrate layer and / or on the surface of the first substrate layer;

[0029] Detecting the actual phase distribution of the metasurface structure layer;

[0030] Obtaining a phase distribution error between an actual phase distribution and a theoretical phase distribution;

[0031] A phase compensation layer is grown on the second surface of the substrate layer and / or the surface of the second substrate layer according to the phase distribution error.

[0032] The phase compensation layer is subjected to at least one phase change process to obtain the theoretical phase distribution.

[0033] Compared with the prior art, this application has at least the following beneficial effects:

[0034] The present application provides a reconfigurable metasurface device, comprising: a substrate layer, and a metasurface structure layer and a phase compensation layer respectively located on both sides of the substrate layer; wherein the phase compensation layer is used to perform phase compensation on the metasurface structure layer.

[0035] The phase compensation method of the reconfigurable metasurface device of the present application can compensate for the phase distribution error of the electromagnetic wave caused by the processing of the nanocolumn array of the metasurface structure. At the same time, the reconfigurable metasurface device of the present application can realize the phase compensation of the electromagnetic wave passing through the metasurface structure without changing the structure and shape of its nanocolumn array. At the same time, the refractive index adjustment of the phase change material of the whole region is supported, and the overall refractive index modulation of several unit structure intervals can be performed, and the excitation light that causes the phase change will not be affected by the interference or reflection of the metasurface.

[0036] The present application also provides a method for preparing a reconfigurable metasurface device. This method does not require changing the preparation process of the original metasurface structure, and corrects the original metasurface structure through a phase compensation layer. At the same time, it can support multiple processing of the phase compensation layer after the metasurface is returned, and can correct unqualified products and reduce the scrap rate of the metasurface structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the structure of a metasurface device without a phase compensation layer according to an exemplary embodiment of the present application.

[0038] Figure 2 This is a schematic diagram of the structure of a reconfigurable metasurface device containing a phase compensation layer according to an exemplary embodiment of the present application.

[0039] Figure 3 This is a schematic diagram of the structure of a reconfigurable metasurface device with a double-layer substrate layer containing a phase compensation layer of the present application.

[0040] Figure 4 This is a schematic diagram of the relative positions of the direct writing spots when the phase compensation layer of the exemplary embodiment of the present application is subjected to phase change by laser direct writing.

[0041] Figure 5This is a flow chart of phase compensation of a reconfigurable metasurface device according to Example 1 of the present application.

[0042] Figure 6 Schematic diagram of phase change modulation comparison of the metasurface device of the exemplary embodiment and comparative example of the present application (single-layer substrate).

[0043] Figure 7 Schematic diagram of phase change modulation comparison of the metasurface device of the exemplary embodiment and comparative example of the present application (double-layer substrate). DETAILED DESCRIPTION

[0044] The technical solution of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0045] It is particularly important to point out that similar substitutions and modifications made to the present application are obvious to those skilled in the art, and they are all deemed to be included in the present application. Relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present application to implement and apply the technology of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments.

[0046] If no specific conditions are specified in this application, the preparation shall be carried out under conventional conditions or the conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, for which the manufacturers are not specified, are all conventional products that can be obtained commercially.

[0047] The application is described in detail below.

[0048] At present, the phase adjustment of the metasurface to light is mainly determined by the geometric shape and size of the structural unit and the dielectric constant of the material. However, in the prior art, after the device is prepared, the geometric shape and size of the structure are difficult to change, and the error of the processing technology is inevitable, resulting in the metasurface function not achieving the expected effect.

[0049] According to the optical phase propagation formula: Where λ is the wavelength of light, n effis the effective refractive index of the light field transmission medium, and L is the transmission distance. It can be seen that the transmission phase of the light wave can be regulated by changing the refractive index of the transmission medium. Phase change material, as an optical material with high refractive index contrast and non-volatile properties, can continuously adjust the refractive index under the stimulation of light, electricity, heat, etc., and is an ideal material for flexibly adjusting the phase of the light field. The principle is that under the stimulation of external environmental conditions, the phase change material produces a change in the lattice state, thereby causing changes in the refractive index and transmittance. The refractive index and extinction coefficient of the phase change material determine the number of states of modulation. Phase change materials with large differences in refractive index or extinction coefficient can provide a larger space for device modulation. Usually there are multiple intermediate states between the amorphous state and the crystalline state, and the different states have completely different physical properties. For example, different intermediate states have different refractive indices, which will then phase modulate the incident light field.

[0050] The design and processing of existing metasurface structure layers usually involves building a phase library based on the metasurface unit structure parameters and phase change, designing the phase distribution of the metasurface layer, converting the phase distribution of the metasurface layer into a unit structure distribution through the phase library, and processing the metasurface structure using photolithography. Because of errors in the actual production and testing process such as processing technology, there will be a phase error between the phase distribution of the processed metasurface and the designed phase distribution.

[0051] There are also existing technologies that utilize the above properties of phase change materials, generally by directly adding phase change materials in the step of preparing the metasurface structure to adjust the phase. This method cannot perform metasurface processing under the current process parameters, and the metasurface devices that have been completed or failed to be prepared still cannot be better utilized or corrected.

[0052] Based on the above problems, the present application provides a reconfigurable metasurface device and a preparation method and a phase compensation method thereof, and is implemented through the following technical solutions.

[0053] In the context of this application, the term "metasurface structure layer" mainly refers to a transmission-type diffraction metasurface, which is composed of a large number of sub-wavelength-sized unit structures arranged periodically. The unit structure consists of a substrate and nanocolumns. Different nanocolumn structure parameters can regulate the phase of the outgoing light.

[0054] In the context of this application, the term "phase error" refers to the difference between the phase distribution of the metasurface design and the phase distribution of the actual metasurface modulating the incident light field, as well as the difference between the phase distribution of the processed metasurface with a fixed function and the phase distribution of the metasurface with a new function to be achieved.

[0055] According to one aspect of the present application, a reconfigurable metasurface device is provided, such as Figure 2As shown, it includes: a metasurface structure layer, a substrate layer, and a phase compensation layer distributed in an array, wherein the metasurface structure layer and the phase compensation layer are respectively located on both sides of the substrate layer. Among them, the phase compensation layer can compensate for the phase error between the actual phase and the designed phase of the metasurface. Among them, the metasurface structure layer is a nanocolumn array arranged on the surface of the substrate.

[0056] In some embodiments of the present application, the substrate layer can be made of a material that is transparent to the working band of the diffractive metasurface.

[0057] like Figure 3 As shown, in some embodiments of the present application, the substrate layer includes a first substrate layer, a substrate spacer layer and a second substrate layer in sequence, the super surface structure layer is located on the surface of the first substrate layer, and the phase compensation layer is located on the surface of the second substrate layer.

[0058] The first substrate layer and the second substrate layer can be made of the same material or different materials. The substrate spacing layer can be made of air or other materials with suitable permeability.

[0059] The phase compensation layer is used to compensate for the phase distribution error of the electromagnetic wave caused by the processing error of the nanorod array.

[0060] Optionally, the phase compensation layer can change its refractive index under the stimulation of the external environment to compensate for the phase distribution error caused by processing the nanorod array.

[0061] Optionally, the phase compensation layer also has non-volatile properties.

[0062] The phase compensation layer of the present application can be prepared from phase change materials.

[0063] Optionally, the phase change material includes Sb single substance, Te single substance or sulfide compound phase change material.

[0064] Optionally, the chalcogenide phase change material includes GeTe alloy, GeSb alloy, SbTe alloy, GeSbTe alloy; the GeSbTe alloy includes one or more of Ge2Sb2Te5, Ge3Sb2Te6, GeSb4Te7 and GeSb2Te4.

[0065] Among them, the Ge-Sb-Te series alloys are currently recognized as the most studied and mature phase change materials, especially Ge2Sb2Te5 (GST) with the best comprehensive performance.

[0066] In some examples of the present application, the selection of phase change materials should fully consider the characteristics such as refractive index, extinction coefficient, modulation energy consumption, modulation speed, and holding time. The refractive index and extinction coefficient of the phase change material determine the number of modulation states. Phase change materials with large refractive index differences or large extinction coefficient differences can provide a larger space for device modulation. At the same time, the number of modulated states is determined according to the difference window between the crystalline and amorphous states of the phase change material. The refractive index and crystallization temperature are different under different state numbers. The same thickness of the phase compensation layer and two positions with different refractive indices will cause the optical path of the light passing through the position to change, causing the phase of the outgoing light to change. Therefore, other materials that can realize the above-mentioned phase modulation, including but not limited to phase change materials, distributed splicing of combinations of materials with different refractive indices, etc., also fall within the scope of the present application.

[0067] According to the second aspect of the present application, a method for preparing a reconfigurable supersurface structure is provided, the method comprising: obtaining a substrate, forming a nanocolumn array on a first surface of the substrate, and preparing a supersurface structure layer; and forming a phase compensation layer on a second surface of the substrate.

[0068] Optionally, after forming the phase compensation layer on the second surface of the substrate, a nanorod array is formed on the first surface of the substrate.

[0069] Optionally, forming a phase compensation layer on the second surface of the substrate includes: obtaining a phase distribution error between a measured phase distribution of an electromagnetic wave passing through the metasurface structure and a theoretical phase distribution; and forming a phase compensation layer on the second surface of the substrate according to the phase distribution error.

[0070] Obtaining phase error: Before using the phase compensation layer for phase compensation, the phase distribution can be designed through conventional diffraction metasurface design and processing methods, and the metasurface structure layer can be processed. The actual phase distribution of the processed metasurface structure layer can be measured experimentally, and the designed phase distribution is compared with the actual phase distribution to obtain the phase error distribution.

[0071] Construct a phase library based on the phase change state of the phase change material: divide the phase compensation layer into periods according to the period of the metasurface structure layer or divide it according to the phase change error distribution result, according to the specific situation of the error value and the method of realizing the phase change, simulate the unit structure of the phase compensation layer, and adjust the refractive index, phase change area, phase change thickness and other parameters corresponding to different phase change states between the amorphous and crystalline states of the phase change material to ensure that the corresponding modulation phase obtained can cover the phase value in the phase error distribution.

[0072] The present application does not limit the acquisition of different phase change states of phase change materials. For example, it can be obtained by laser direct writing. Different refractive indices of phase change materials correspond to different crystallization temperatures, and the crystallization temperature can be achieved by optical and electrical means. For example, taking optics as an example, a pulsed laser can be used for phase change direct writing, and the crystallization temperature corresponds to the pulse width of the pulsed laser, that is, the pulse width and duty cycle of the pulsed laser for phase change of the refractive index and laser direct writing are obtained. The crystallization temperature of different states of phase change materials can be controlled by placing the laser direct writing, controlling the laser power density and illumination time, so that the temperature at the illumination position reaches the crystallization temperature of the different states of the phase change material.

[0073] The distribution of the phase change state of the phase change material can be obtained from the phase error distribution of the metasurface structure layer, and the phase change state distribution is mapped to the phase compensation layer, such as Figure 4 The figure shows a schematic diagram of the laser direct writing spot on the phase compensation layer. According to the laser direct writing spot size and the periodic division of the phase compensation layer, fine phase change direct writing is performed to achieve phase compensation of the diffraction-type metasurface.

[0074] Phase compensation: According to the phase error distribution obtained above and the phase library constructed by the phase change state, the distribution of the phase change state based on the phase change material can be obtained. The phase compensation layer is subjected to phase change processing according to the above phase change state distribution to complete the phase error compensation of the metasurface structure layer.

[0075] According to another aspect of the present application, a metasurface phase compensation method is provided, comprising:

[0076] According to the theoretical phase distribution, a super surface structure layer distributed in a periodic array is grown on the first surface of the substrate layer;

[0077] Detecting the actual phase distribution of the metasurface structure layer;

[0078] Obtaining a phase distribution error between the actual phase distribution and the theoretical phase distribution;

[0079] growing a phase compensation layer on the second surface of the substrate layer according to the phase distribution error,

[0080] The phase compensation layer is subjected to at least one phase change process to obtain the theoretical phase distribution.

[0081] Optionally, the phase compensation method includes: obtaining a phase distribution error between a measured phase distribution of an electromagnetic wave passing through a metasurface structure and a theoretical phase distribution; and processing the phase compensation layer according to the phase distribution error.

[0082] Optionally, the phase compensation layer material can change its refractive index under the stimulation of the external environment, so that the phase distribution of the electromagnetic wave passing through the phase compensation layer material changes; wherein the phase change processing includes: converting the phase distribution error into the phase distribution of the electromagnetic wave of the phase change compensation layer material; processing the phase change compensation layer material according to the mapping relationship between the phase distribution and the phase change state to obtain a metasurface structure after phase compensation.

[0083] Optionally, after processing the phase change compensation layer material according to the phase distribution of the electromagnetic wave, it also includes: exciting the phase change compensation layer through the external environment to adjust the refractive index of the phase change compensation layer, thereby adjusting the phase distribution of the electromagnetic wave passing through the metasurface.

[0084] Optionally, after the phase change compensation layer is stimulated by the external environment, it also includes: performing a functional test on the metasurface after the phase change compensation layer is stimulated; if the functional test fails, obtaining a phase error distribution between the measured phase distribution and the theoretical phase distribution of the electromagnetic wave of the metasurface after the stimulated phase change compensation; and re-processing the phase compensation layer according to the phase error distribution.

[0085] Optionally, when the phase change compensation layer is a phase change material, the external environment is a laser, and the electromagnetic wave is a light wave, the above method also includes: applying lasers of different energies to the regions of the phase change compensation layer corresponding to each nanocolumn array, so that the phase state of the phase change material corresponding to the region changes, so as to record the phase of the laser passing through the corresponding metasurface and the change in phase, and obtain a phase library based on each phase change material; the phase library includes each of the nanocolumn arrays, the parameters corresponding to each energy laser, the refractive index corresponding to each phase state of each phase change material, the phase change thickness, the area of ​​the phase change material and the corresponding relationship with the laser phase.

[0086] Optionally, processing the phase compensation layer according to the phase distribution error includes: processing the phase compensation layer according to the phase distribution error and the phase library.

[0087] Optionally, lasers of different energies include lasers of different energies formed by combinations of multiple power densities and multiple irradiation times.

[0088] According to another aspect of the application, a device is provided, comprising the metasurface structure provided in the first aspect of the application, or comprising the metasurface structure prepared by the method provided in the second aspect, or using the phase compensation method of the application to perform phase compensation on the metasurface.

[0089] The technical solution of the present application is further described below in conjunction with specific embodiments.

[0090] Example 1

[0091] The Fourier formula is used to calculate the phase distribution phase_theory(x,y) of the transmission-type cylindrical metasurface structure layer. According to the calculated phase distribution results, a transmission-type phase-modulated metasurface with a working band of 1550nm is prepared (such as Figure 1 The unit structure is cylindrical, the height of the cylinder is fixed, and the diameter of the cylinder is changed to achieve a modulation phase coverage of 0-2pi. The height of the column is 940nm amorphous silicon, the period is 1000nm, and the substrate layer is 500μm thick SiO2.

[0092] A layer of Ge2Sb2Te5 phase change material is deposited on the other surface of the substrate layer by magnetron sputtering; the phase distribution phase_test(x,y) of the metasurface with Ge2Sb2Te5 phase change material is tested; and the phase error distribution err_phase(x,y)=phase_theory(x,y)-phase_test(x,y) between theoretical calculation and actual measurement is obtained.

[0093] According to the fact that the refractive index of the Ge2Sb2Te5 phase change material changes from about 6.1 in the crystalline state to about 3.9 in the amorphous state under the action of a 1550nm laser, the refractive index change is mapped to the phase change through FDTD modeling and simulation; different refractive indices correspond to different phase change states of the Ge2Sb2Te5 phase change material, and then the phase error distribution err_phase(x,y) is mapped to the distribution of the phase change state err_GST(x,y).

[0094] The phase compensation layer is phase-changed according to the distribution of the above-mentioned phase change states by laser direct writing. By controlling the power and illumination time of the direct writing laser in the laser direct writing system, multiple phase change direct writing of the phase change material can be realized.

[0095] After the direct writing is completed, the phase distribution test and the metasurface function test are performed on the metasurface at this time, and compared with the designed phase distribution phase_theory(x,y). If the measured phase distribution at this time is consistent with the designed phase distribution, and the function of the metasurface can achieve the expected effect, the phase compensation is completed.

[0096] If there is still a large error between the measured phase distribution and the designed phase distribution at this time and the metasurface function cannot achieve the expected effect, repeat the above steps according to the new phase error distribution, iterate until the measured phase distribution is consistent with the designed phase distribution, and the function of the metasurface can achieve the expected effect, thus completing the phase compensation.

[0097] Example 2

[0098] A 500 μm thick SiO2 substrate is selected, a phase change material is evaporated on the first surface, and a material (such as a 100 μm thick SiO2 substrate) is evaporated on the second surface for processing a super-surface pillar structure. Figure 2 shown).

[0099] Select phase change materials, and simulate and construct a phase library of film thickness, area, and phase change according to the refractive index under different phase change states. Based on this, the film thickness of the phase change material is selected. This embodiment uses a 23nm Sb2Se3 film to achieve phase change between crystalline and amorphous states through laser direct writing, where the refractive index of the crystalline state is 4.050 and the refractive index of the amorphous state is 3.285. Fixed film thickness is used to achieve phase change through changes in the area of ​​crystalline and amorphous states.

[0100] Based on the above substrate material and phase change material as the base, the material layer used for processing the supersurface column structure by evaporation is prepared according to the traditional supersurface preparation process.

[0101] After the preparation is completed, the phase distribution of the metasurface is characterized. If there is an error, phase compensation is performed through the phase compensation layer. If there is no error, the phase compensation layer remains unchanged and does not affect the realization of the metasurface function.

[0102] Example 3

[0103] For the metasurface device with a phase compensation layer that has been processed in Example 2, its original function is to achieve a focusing function with a focal length of 100 μm, and now it is necessary to achieve a focusing function with a focal length of 150 μm.

[0104] According to the height and material parameters of the existing metasurface pillar structure, a metasurface phase distribution with a focal length of 150μm is designed.

[0105] Calculate the phase difference between the newly designed phase distribution with a focal length of 150 μm and the original phase distribution with a focal length of 100 μm.

[0106] The phase difference calculated above is compensated by the phase compensation layer.

[0107] Because of the reconfigurable properties of phase change materials, the functions of metasurfaces that have been processed and solidified can be reconfigured.

[0108] Example 4

[0109] A 300 μm SiO2 material is selected as the first substrate layer, and 1046 nm amorphous silicon is plated on the first substrate layer to make super-surface pillars as a super-lens that can realize the focusing function, and the focal length is set to 100 μm.

[0110] Another 300 μm SiO2 material is selected as the second substrate layer, and a 30 nm Sb2Se3 material is plated on the second substrate layer as a phase compensation layer.

[0111] In order to transform the superlens of the first substrate layer and the supersurface pillars into a new superlens with a focal length of 110μm, the phase distribution of the new superlens is compared with the phase distribution of the original superlens to obtain the required phase compensation distribution.

[0112] The phase change material layer on the second substrate layer is processed according to the above phase compensation distribution to obtain a phase compensation layer.

[0113] By aligning and cascading the superlens of the first substrate layer and the phase compensation layer of the second substrate layer, the superlens with an original focal length of 100 μm can be transformed into a superlens with a focal length of 110 μm.

[0114] By modifying the phase change degree of the phase change material on the second substrate layer, the parameters and functions of the metasurface of the first substrate layer can be modified.

[0115] Comparative Example 1

[0116] A metasurface, comprising, from top to bottom, a phase compensation layer, a metasurface structure layer, a substrate layer (such as Figure 6 B).

[0117] Since the phase change material is located above the supersurface processing layer, the phase compensation layer can only be plated on the supersurface material before the supersurface structural layer is micro-nano processed, and then the supersurface is micro-nano processed. At this time, the phase compensation layer is also micro-nano processed accordingly.

[0118] Comparing the above comparative examples with the embodiments of the present application, it can be seen that the reconfigurable metasurface of the present application can perform phase compensation on the already processed metasurface by coating the phase change material again. However, comparative example 1 does not support phase compensation on the already processed metasurface.

[0119] At the same time, in the preparation process of the reconfigurable metasurface of the present application, the order of growing the phase compensation layer can be flexibly adjusted according to the actual operation, and it does not affect the processing technology of the metasurface pillars. However, in the comparative metasurface structure, the phase compensation layer and the metasurface material heterogeneous integrated layer need to be micro-nano processed, which requires complex process adjustments compared to the micro-nano processing of only the metasurface material. The solution of the present application is flexible to operate, saves phase change reset time, and one metasurface can be equipped with multiple phase change layers, saving the processing cost of the metasurface.

[0120] For phase change modulation of phase change materials by laser direct writing, such as Figure 6 A. Figure 7 As shown in A, the laser used for phase modulation in the present application is all irradiated on the phase change material, and the phase change is uniform; the present application can perform phase compensation through the phase compensation layer according to the phase distribution of the processed super surface layer and the phase difference between the new target phase distribution; at the same time, the present application can also configure multiple phase compensation layers for the same processed super surface layer, and multiple functions can be reconstructed by only aligning two layers.

[0121] like Figure 6 B. Figure 7 As shown in B, in the comparative example, the laser is irradiated on the phase change material processed into a micro-nano structure, and only a part of the light energy is irradiated on the phase change material. The utilization rate of the limited area of ​​phase change modulation is low, and a part of a pillar structure will be modulated by phase change.

[0122] In the comparative example, the phase change material is located above the metasurface processing layer. It is only possible to plate a phase compensation layer on the metasurface material before the metasurface processing, and then perform micro-nano processing on the metasurface. At this time, the phase compensation layer is also micro-nano processed accordingly. The function can only be reconstructed by directly writing and resetting the phase change on the same phase change material.

[0123] The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A reconfigurable metasurface device, characterized in that: include: A substrate layer, and a metasurface structure layer and a phase compensation layer respectively located on both sides of the substrate layer; Wherein, the phase compensation layer is used to perform phase compensation on the metasurface structure layer.

2. The reconfigurable metasurface device according to claim 1, characterized in that: The substrate layer includes a first substrate layer, a substrate spacer layer and a second substrate layer in sequence; Wherein, the super-surface structure layer is located on the surface of the first substrate layer, and the phase compensation layer is located on the surface of the second substrate layer.

3. The reconfigurable metasurface device according to claim 1 or 2, characterized in that: The phase compensation layer is made of phase change material; Optionally, the phase change material is composed of Sb single substance, Te single substance and / or sulfide compound phase change material.

4. The reconfigurable metasurface device according to claim 3, characterized in that: The chalcogenide phase change material includes: germanium antimony telluride, antimony sulfide, antimony selenide, antimony telluride, germanium telluride or germanium antimony selenium telluride compounds; Wherein, the germanium antimony tellurium compound includes: one or more of Ge2Sb2Te5, Ge3Sb2Te6, GeSb4Te7 and GeSb2Te4.

5. A method for preparing a reconfigurable metasurface device, characterized in that: include: According to the theoretical phase distribution, a super surface structure layer distributed in a periodic array is grown on the first surface of the substrate layer and / or on the surface of the first substrate layer; Detecting the actual phase distribution of the metasurface structure layer; Obtaining a phase distribution error between the actual phase distribution and the theoretical phase distribution; Growing a phase compensation layer on the second surface of the substrate layer and / or on the surface of the second substrate layer according to the phase distribution error to obtain the reconfigurable metasurface device; Wherein, the phase compensation layer is used to perform phase compensation on the metasurface structure layer.

6. The method for preparing a reconfigurable surface device according to claim 5, characterized in that: Growing a phase compensation layer on the second surface of the substrate layer and / or on the surface of the second substrate layer according to the phase distribution error comprises: According to the period of the metasurface structure layer distributed in a periodic array, or according to the phase distribution error, the phase compensation layer is divided into regions to obtain the phase distribution of the phase change material in different regions and obtain the phase library of the phase change material; A phase compensation layer is grown on the second surface of the substrate layer and / or on the surface of the second substrate layer according to the phase library and the phase distribution error.

7. The method for preparing a reconfigurable surface device according to claim 5, characterized in that: The phase compensation layer is made of phase change material.

8. The method for preparing a reconfigurable surface device according to claim 7, characterized in that: The phase change material includes: one or more of Sb single substance, Te single substance and sulfur series compound.

9. The method for preparing a reconfigurable surface device according to claim 8, characterized in that: The chalcogenide phase change material includes: germanium antimony telluride, antimony sulfide, antimony selenide, antimony telluride, germanium telluride or germanium antimony selenium telluride compounds; Wherein, the germanium antimony tellurium compound includes: one or more of Ge2Sb2Te5, Ge3Sb2Te6, GeSb4Te7 and GeSb2Te4.

10. A phase compensation method for a reconfigurable metasurface device, characterized in that: include: According to the theoretical phase distribution, a super surface structure layer distributed in a periodic array is grown on the first surface of the substrate layer; Detecting the actual phase distribution of the metasurface structure layer; Obtaining a phase distribution error between the actual phase distribution and the theoretical phase distribution; growing a phase compensation layer on the second surface of the substrate layer according to the phase distribution error, The phase compensation layer is subjected to at least one phase change process to obtain the theoretical phase distribution.

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