Reconfigurable metasurface device and preparation method and phase compensation method thereof

Abstract

The application 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 located on both sides of the substrate layer respectively; and the phase compensation layer is used for phase compensation of the metasurface structure layer. The phase compensation method of the reconfigurable metasurface device can realize phase compensation of the metasurface structure without changing the nanometer pillar array of the metasurface structure and the preparation process.

Description

TECHNICAL FIELD

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

[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-jamming. In the civil field, electromagnetic waves have a wide range of applications in electronic communication, medical treatment, environmental monitoring, and home life. It is closely related to our life, and plays an extremely important role in both daily life and military life. Therefore, it is necessary to effectively control electromagnetic waves, which has become a research hotspot in various fields.

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

[0004] Diffractive metasurface devices are a type of metasurface optical element 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 control of light waves. These devices are commonly used in beam shaping, wavefront control, optical imaging, and spectral analysis. Such metasurfaces are composed of subwavelength-sized microstructure units that can manipulate the wavefront of light in a specific way, thereby introducing anomalous phase jumps. From the unit resonance mode, it can be divided into transmission phase units and geometric phase units. Propagation phase-reliant metalens (PR-metalens) refers to the control of the exit phase of electromagnetic waves after passing through a dielectric metasurface by modulating the cumulative phase of electromagnetic waves after passing through the metasurface. Geometric phase, also known as Pancharatnam-Berry (PB) phase, occurs when the unit of the superlens is an anisotropic nanocolumn. The length and width of the nanocolumn can be regarded as the major axis and slow axis. This anisotropic structure will produce a phase difference along the two principal axes. Similar to a wave plate, in the case of circularly polarized light incidence, by adjusting the rotation angle of the anisotropic unit structure on the substrate, an additional phase can be introduced that is only related to the rotation angle. By modulating the phase of the light exiting the metasurface, the desired imaging function can be achieved in the far field or near field through the interference superposition principle of light.

[0005] The phase modulation of the light by the above super surface is mainly determined by the geometric shape and size of the structural unit, and the dielectric constant of the material. When 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 cause the error between the designed phase and the actual phase. Therefore, in the actual use process, there will be a phase difference between the designed phase distribution and the actual phase distribution after the super surface is processed, which will cause the function of the super surface to not achieve the expected effect. Once the super surface is processed, the physical structure cannot be changed, so how to compensate the phase of the super surface is particularly important. SUMMARY

[0006] In order to solve the above problems existing in the prior art, the present application aims to provide a reconfigurable super surface device and a preparation method and a phase compensation method thereof. Through a reconfigurable super surface structure, a preparation method, a compensation method and equipment, a phase compensation layer is additionally arranged on the other surface of the substrate relative to the nanometer column, which can adjust the phase distribution of the electromagnetic wave passing through the super surface structure, and realize the adjustment of the phase error of the original super surface.

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

[0008] The phase compensation layer is used for phase compensation of the super surface structure layer.

[0009] The substrate layer comprises a first substrate layer, a substrate spacing 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 chalcogenide phase change material.

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

[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 preparation method of a reconfigurable super surface device is provided, comprising:

[0015] According to the theoretical phase distribution, growing, on a first surface of the substrate layer and / or a surface of the first substrate layer, a metasurface structure layer arranged in a periodic array;

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

[0017] obtaining a phase distribution error between the actual phase distribution and the theoretical phase distribution;

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

[0019] The phase compensation layer is configured to compensate a phase of the metasurface structure layer.

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

[0021] dividing the phase compensation layer into different regions according to a period of the metasurface structure layer arranged in a periodic array, or according to the phase distribution error, obtaining a phase distribution of a phase change material in each region, and obtaining a phase library of the phase change material;

[0022] growing, on a second surface of the substrate layer and / or a surface of the second substrate layer, the phase compensation 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, Te and a chalcogenide compound.

[0025] According to some embodiments of the present application, the chalcogenide phase change material includes germanium antimony tellurium, antimony sulfide, antimony selenide, antimony telluride, germanium tellurium or germanium antimony selenide tellurium.

[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, including:

[0028] According to the theoretical phase distribution, growing, on a first surface of the substrate layer and / or a surface of the first substrate layer, a metasurface structure layer arranged in a periodic array;

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

[0030] obtaining a phase distribution error between the actual phase distribution and the theoretical phase distribution;

[0031] 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,

[0032] performing at least one phase change process on the phase compensation layer to obtain the theoretical phase distribution.

[0033] Compared with the prior art, the present application at least includes 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 for phase compensation of 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 electromagnetic waves caused by the nanorod array processing of the metasurface structure. At the same time, the reconfigurable metasurface device of the present application can realize phase compensation of electromagnetic waves passing through the metasurface structure without changing the structure and shape of the nanorod array. At the same time, the refractive index adjustment of the phase change material in the whole region can realize the overall modulation of the refractive index in a plurality of unit structure intervals, and the excitation light causing the phase change will not be affected by the interference or reflection of the metasurface.

[0036] The present application also provides a preparation method of a reconfigurable metasurface device, which does not need to change the preparation process of the original metasurface structure, and modifies the original metasurface structure through the phase compensation layer. At the same time, the phase compensation layer can be processed multiple times after the metasurface is cut, and unqualified products can be modified, thereby reducing the scrap rate of the metasurface structure. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a structure schematic diagram of the metasurface device without a phase compensation layer of the example embodiment of the present application.

[0038] Figure 2 It is a structure schematic diagram of the reconfigurable metasurface device with a phase compensation layer of the example embodiment of the present application.

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

[0040] Figure 4 It is a relative position schematic diagram of the direct writing light spot for phase change of the phase compensation layer of the example embodiment of the present application.

[0041] Figure 5Flow chart for phase compensation of the reconfigurable metasurface device of Example 1 of the present application.

[0042] Figure 6 Comparison diagram of phase change modulation of the metasurface device of the example embodiments and comparative examples of the present application (single-layer substrate).

[0043] Figure 7 Comparison diagram of phase change modulation of the metasurface device of the example embodiments and comparative examples of the present application (double-layer substrate). DETAILED DESCRIPTION

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

[0045] It is particularly pointed out that similar replacements and changes made for the present application are obvious to those skilled in the art, and they are considered to be included in the present application. The related personnel can obviously make changes or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present application, to realize and apply the technology of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0046] Unless otherwise specified in the present application, the conventional conditions or the conditions recommended by the manufacturer are used, and the raw materials or excipients used, and the reagents or instruments used, if not specified by the manufacturer, are all conventional products that can be obtained by purchase.

[0047] The present application will be described in detail below.

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

[0049] According to the light phase propagation formula: where λ is the wavelength of light, n effis the effective refractive index of the light field transmission medium, L is the transmission distance. It can be seen that the transmission phase of the light wave can be controlled by changing the refractive index of the transmission medium. As an optical material with high refractive index contrast and non-volatile characteristics, the phase change material can continuously adjust the refractive index under the excitation of light, electricity, heat and other excitations, and is an ideal material for flexible adjustment of the phase of the light field. The principle is that the phase change material produces a change in the lattice state under the stimulation of external environmental conditions, thereby causing a change in the refractive index and the transmittance. The refractive index and the extinction coefficient of the phase change material determine the number of modulation states, and the phase change material with large refractive index difference or large extinction coefficient difference can provide more space for modulation of the device. Usually, there are multiple intermediate states between the amorphous state and the crystalline state, and different intermediate states have completely different physical properties, such as different refractive indices, which will further modulate the phase of the incident light field.

[0050] The design and processing of the existing super surface structure layer is usually to construct a phase library according to the super surface unit structure parameters and the phase change amount, to design the phase distribution of the super surface layer, to convert the phase distribution of the super surface layer into a unit structure distribution by using the above-mentioned phase library, and to process the super surface structure by using the photolithography technology. Because of the errors in the actual production and testing process such as the processing technology, the phase distribution of the processed super surface will have a phase error with the designed phase distribution.

[0051] There are also existing technologies that use the above-mentioned properties of phase change materials, which generally add phase change materials directly in the step of preparing the super surface structure to adjust the phase. This method cannot process the super surface under the existing process parameters, and the super surface device that is prepared successfully or fails cannot be better utilized or corrected.

[0052] Based on the above problems, the present application provides a reconfigurable super surface device and its preparation method and phase compensation method, and realizes the following technical solutions.

[0053] In the context of the present application, the term "super surface structure layer" mainly refers to a transmissive diffraction super surface, which is composed of a large number of sub-wavelength size unit structures arranged periodically, and the unit structure is composed of a substrate and a nano pillar, and different nano pillar structure parameters can control the phase of the outgoing light.

[0054] In the context of the present application, the term "phase error" refers to the difference between the phase distribution of the super surface design and the phase distribution of the actual processed super surface for modulating the incident light field, and the difference between the phase distribution of the super surface with fixed function that has been processed and the phase distribution of the super surface with new function that is intended to be realized.

[0055] According to an aspect of the present application, a reconfigurable super surface device is provided, such as Figure 2As shown, the super-holographic lens includes: a super-holographic lens structure layer arranged in an array, a substrate layer, and a phase compensation layer, the super-holographic lens structure layer and the phase compensation layer are respectively located on two sides of the substrate layer. The phase compensation layer can compensate for the phase error between the actual phase of the super-holographic lens and the designed phase. The super-holographic lens structure layer is a nano-pillar array arranged on the surface of the substrate.

[0056] In some embodiments of the present application, the substrate layer can be selected according to the working waveband of the diffractive super-holographic lens, and the material that transmits the waveband.

[0057] As shown in the drawings, Figure 3 In some embodiments of the present application, the substrate layer includes a first substrate layer, a substrate spacing layer, and a second substrate layer in sequence, the super-holographic lens structure layer is arranged on the surface of the first substrate layer, and the phase compensation layer is arranged 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 appropriate transmission rate.

[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 nano-pillar array.

[0060] Optionally, the phase compensation layer can change the refractive index under the excitation of the external environment to compensate for the phase distribution error caused by the processing of the nano-pillar array.

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

[0062] The phase compensation layer of the present application can be prepared from a phase change material,

[0063] Optionally, the phase change material includes Sb element, Te element, or a chalcogenide phase change material.

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

[0065] The Ge-Sb-Te series alloy is currently the most recognized and most mature phase change material, and Ge2Sb2Te5(GST) is the most optimal in terms of comprehensive performance.

[0066] In some examples of the present application, the selection of the phase change material takes into full account the characteristics of refractive index, extinction coefficient, modulation energy consumption, modulation speed, retention time, etc. Among them, the refractive index and extinction coefficient of the phase change material determine the number of states of the modulation, and the phase change material with large refractive index difference or extinction coefficient difference can provide more space for the modulation of the device. At the same time, the difference window between the crystalline state and the amorphous state of the phase change material determines the number of states that can be modulated. The refractive index and crystallization temperature are different under different state numbers. For a phase compensation layer with the same thickness, 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 achieve the above phase modulation, including but not limited to phase change materials, different refractive index material combination distributed splicing, etc., also belong to the scope of the present application.

[0067] According to a second aspect of the present application, a preparation method of a reconfigurable metasurface structure is provided, the method comprising: obtaining a substrate, forming a nanocolumn array on a first surface of the substrate, and preparing a metasurface 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, the nanocolumn array is formed on the first surface of the substrate.

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

[0070] Obtaining the phase error: before phase compensation by the phase compensation layer, the phase distribution can be designed by a conventional diffractive metasurface design and processing method, the metasurface structure layer is processed, the actual phase distribution of the processed metasurface structure layer is measured by experiment, and the design phase distribution and the actual phase distribution are compared to obtain the phase error distribution.

[0071] Building a phase library based on the phase change state of the phase change material: the phase compensation layer is divided periodically according to the period of the metasurface structure layer or according to the phase change error distribution result, the unit structure of the phase compensation layer is simulated, and the refractive index, phase change area, phase change thickness, etc. between the amorphous state and the crystalline state of the phase change material are adjusted to ensure that the corresponding modulation phase obtained can cover the phase values in the phase error distribution.

[0072] The application does not limit the obtaining of different phase change states of the phase change material. For example, a laser direct writing method can be used. Different refractive indexes of the phase change material correspond to different crystallization temperatures, and the crystallization temperature can be achieved by optical and electrical methods. For example, in the optical case, a pulse laser can be used for phase change direct writing, and the crystallization temperature corresponds to the pulse width of the pulse laser, that is, the refractive index and the pulse width and duty cycle of the pulse laser of the phase change direct writing are obtained. The crystallization temperature of different states of the phase change material can be controlled by the power density and illumination time of the laser through laser direct writing so that the temperature at the illumination position reaches the crystallization temperature of different states of the phase change material.

[0073] The distribution of the phase change state of the phase change material can be obtained by the phase error distribution of the metasurface structure layer, and the phase change state distribution is mapped to the phase compensation layer, as shown in Figure 4 The figure shows a schematic diagram of a laser direct writing spot on the phase compensation layer. According to the size of the laser direct writing spot and the period division of the phase compensation layer, fine phase change direct writing is performed, and phase compensation of the diffractive metasurface is achieved.

[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 error compensation of the metasurface structure layer can be completed by phase change processing of the phase compensation layer according to the phase change state distribution.

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

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

[0077] The actual phase distribution of the metasurface structure layer is detected;

[0078] The phase distribution error between the actual phase distribution and the theoretical phase distribution is obtained;

[0079] According to the phase distribution error, a phase compensation layer is grown on a second surface of the substrate layer,

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

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

[0082] Optionally, the phase compensation layer material can change the refractive index under the excitation 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; according to the mapping relationship between the phase distribution and the phase change state, the phase change compensation layer material is processed to obtain the super surface structure after phase compensation.

[0083] Optionally, after the phase change compensation layer material is processed according to the phase distribution of the electromagnetic wave, it further includes: exciting the phase change compensation layer through the external environment to adjust the refractive index of the phase change compensation layer, so as to adjust the phase distribution of the electromagnetic wave passing through the super surface.

[0084] Optionally, after the phase change compensation layer is excited by the external environment, it further includes: function test of the super surface after exciting the phase change compensation layer; in the case of unqualified function test, the phase error distribution of the measured phase distribution and the theoretical phase distribution of the electromagnetic wave passing through the super surface after the phase change compensation is obtained; the phase compensation layer is processed again according to the phase error distribution.

[0085] Optionally, in the case that the phase change compensation layer is a phase change material, the external environment is laser, and the electromagnetic wave is light wave, the above method further includes: applying laser with different energy to the region of the phase change compensation layer corresponding to each kind of nanometer column array respectively, 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 super surface and the change of the phase, and obtain the phase library based on each kind of phase change material; the phase library includes the corresponding relationship between each kind of nanometer column array, each kind of energy laser, the refractive index of each kind of phase state of each kind of phase change material, the phase change thickness, and the area of the phase change material.

[0086] Optionally, the processing of 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, the laser with different energy includes laser with different energy formed by combination of multiple power density and multiple irradiation time.

[0088] According to another aspect of the application, a device is provided, which includes the super surface structure provided by the first aspect of the application, or the super surface structure prepared by the method provided by the second aspect, or the super surface phase compensated by the phase compensation method of the application.

[0089] The technical solutions of the application will be further introduced below in combination with specific embodiments.

[0090] Embodiment 1

[0091] The phase distribution phase_theory(x, y) of the transmission type cylindrical metasurface structure layer is calculated by using Fourier formula. According to the calculated phase distribution result, a metasurface (as shown in Figure 1 ) with a working wave band of 1550 nm and a transmission type phase modulation is prepared. The unit structure of the metasurface is a cylinder. The fixed cylinder height is changed to change the cylinder diameter to realize the modulation phase covering 0-2pi. The amorphous silicon with a column height of 940 nm, a period of 1000 nm and a substrate layer of 500 mu m thick SiO2.

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

[0093] According to the fact that the refractive index of the Ge2Sb2Te5 phase change material is about 6.1 in the crystalline state and about 3.9 in the amorphous state under the action of the laser with a wavelength of 1550 nm, the refractive index change is mapped to the phase change by FDTD modeling simulation. Different refractive indexes 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 err_GST(x, y) of the phase change state.

[0094] The phase change of the phase compensation layer is carried out according to the above distribution of the phase change state by laser direct writing. The power and illumination time of the direct writing laser in the laser direct writing system are controlled to realize the direct writing of the phase change material in multiple phase change states.

[0095] After the direct writing is completed, the phase distribution of the metasurface at this time is tested, and the function of the metasurface is tested. The actual measured phase distribution at this time is compared with the designed phase distribution phase_theory(x, y). If the actual 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 the actual measured phase distribution at this time still has a large error compared with the designed phase distribution, and the function of the metasurface cannot achieve the expected effect, the above steps are repeated according to the new phase error distribution until the actual measured phase distribution is consistent with the designed phase distribution, and the function of the metasurface can achieve the expected effect, and the phase compensation is completed.

[0097] Embodiment 2

[0098] A 500 mu m thick SiO2 substrate is selected. A phase change material is evaporated on the first surface thereof. A material (as shown in Figure 2 ) for processing the metasurface column structure is evaporated on the second surface thereof.

[0099] The phase change material is selected according to the refractive index in different phase change states, and a phase library of film thickness, area, and phase change amount is simulated and constructed. Based on this, the film thickness of the phase change material is selected, and in this embodiment, a 23 nm Sb2Se3 thin film is used to realize the phase change between the crystalline state and the amorphous state through laser direct writing, wherein the refractive index of the crystalline state is 4.050, and the refractive index of the amorphous state is 3.285. By fixing the film thickness, the phase change is realized by changing the area of the crystalline state and the amorphous state.

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

[0101] After preparation, the phase distribution of the super surface is characterized. If there is an error, the phase compensation layer is used for phase compensation. If there is no error, the phase compensation layer remains unchanged and does not affect the function of the super surface.

[0102] Embodiment 3

[0103] For the super surface device with a phase compensation layer processed in embodiment 2, the original function is to realize the focusing function with a focal length of 100 μm, and now the focusing function with a focal length of 150 μm needs to be realized.

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

[0105] 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 is calculated.

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

[0107] Because of the reconfigurable characteristics of the phase change material, the function of the super surface that has been processed and solidified can be reconfigured.

[0108] Embodiment 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 process the super surface column, which is used 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 30 nm Sb2Se3 material is plated on the second substrate layer to form a phase compensation layer.

[0111] To change the first substrate layer and the superlens of the super surface column into a new superlens with a focal length of 110 pm, 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 phase compensation distribution to obtain a phase compensation layer.

[0113] The superlens of the first substrate layer and the phase compensation layer of the second substrate layer are aligned and cascaded, so that the superlens with an original focal length of 100 pm is changed into a superlens with a focal length of 110 pm.

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

[0115] Comparative Example 1

[0116] A super surface sequentially includes, from top to bottom: a phase compensation layer, a super surface structure layer, and a substrate layer (such as Figure 6 B.

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

[0118] Comparing the above comparative example with the embodiments of the present application, it can be seen that the reconfigurable super surface of the present application can plate the phase change material on the already processed super surface again for phase compensation. Comparative Example 1 does not support phase compensation for the already processed super surface.

[0119] Meanwhile, in the preparation process of the reconfigurable super surface of the present application, the order of growing the phase compensation layer can be flexibly adjusted according to actual operation, and it does not affect the processing technology of the super surface column. However, the super surface structure of the comparative example needs to be micro-nano processed on the phase compensation layer and the super surface material hetero-integrated layer, which needs complex process adjustment compared with only micro-nano processing of the super surface material. The scheme of the present application is flexible to operate, saves phase change reset time, one super surface can be equipped with multiple phase change layers, and saves the processing cost of the super surface.

[0120] The phase change modulation of the phase change material by laser direct writing is shown in Figure 6 A, Figure 7 A, all the lasers for phase modulation of the present application are irradiated on the phase change material, and the phase change is uniform; the present application can compensate the phase difference between the phase distribution of the already processed super surface layer and the new target phase distribution through the phase compensation layer; at the same time, the present application can also configure multiple phase compensation layers for the same processed super surface layer, and only needs to align the two layers to reconfigure multiple functions.

[0121] As Figure 6 B, Figure 7 In the comparative example, the laser irradiates on the phase change material to be processed into a micro-nano structure, only a part of light energy irradiates on the phase change material, the utilization rate of the limited area of the phase change modulation is low, and part of the column structure is phase change modulated.

[0122] In the comparative example, the phase change material is located above the metasurface processing layer, and can only be plated on the phase compensation layer above the metasurface material before the metasurface processing, and then the metasurface micro-nano processing is performed. At this time, the phase compensation layer is also micro-nano processed, and the function reconstruction needs to be performed by phase change direct writing and resetting of the same phase change material.

[0123] The above description of the embodiments is only used to help understand the method and its core idea of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope 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 located on both sides of the substrate layer, respectively; The phase compensation layer is used to perform phase compensation on the metasurface structure layer. The phase compensation layer is made of a phase change material; The phase compensation layer may be one or more layers; The substrate layer comprises, in sequence, a first substrate layer, a substrate spacer layer, and a second substrate layer; Wherein, the metasurface 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; The substrate spacer layer is air; Among them, 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 the processing of the nanopillar array.

2. The reconfigurable metasurface device according to claim 1, characterized in that, The phase change material is composed of elemental Sb, elemental Te, and / or chalcogenide compound phase change materials.

3. The reconfigurable metasurface device according to claim 2, characterized in that, The chalcogenide phase change materials include: germanium-antimony-tellurium, antimony sulfide, antimony selenide, antimony telluride, germanium-tellurium, or germanium-antimony-selenium-tellurium compounds; The germanium-antimony-tellurium alloy includes one or more of Ge2Sb2Te5, Ge3Sb2Te6, GeSb4Te7, and GeSb2Te4.

4. A method for fabricating a reconfigurable metasurface device according to any one of claims 1-3, characterized in that, include: Based on the theoretical phase distribution, a metasurface structure layer with a periodic array distribution is grown on the first surface of the substrate layer and / or the surface of the first substrate layer. Detect the actual phase distribution of the metasurface structure layer; The phase distribution error between the actual phase distribution and the theoretical phase distribution is obtained; Based on the phase distribution error, a phase compensation layer is grown on the second surface of the substrate and / or the surface of the second substrate to obtain the reconfigurable metasurface device. The phase compensation layer is used to perform phase compensation on the metasurface structure layer.

5. The method for fabricating a reconfigurable surface device according to claim 4, characterized in that, Based on the phase distribution error on the second surface of the substrate layer, and / or the surface of the second substrate layer, a phase compensation layer is grown comprising: Based on the period of the periodically arrayed metasurface structure layer, or based on 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 the phase library of the phase change material is obtained. Based on the phase library and the phase distribution error, a phase compensation layer is grown on the second surface of the substrate layer and / or the surface of the second substrate layer.

6. The method for fabricating a reconfigurable surface device according to claim 4, characterized in that, The phase compensation layer is made of a phase change material.

7. The method for fabricating a reconfigurable surface device according to claim 6, characterized in that, The phase change material includes one or more of elemental Sb, elemental Te, and chalcogenides.

8. The method for fabricating a reconfigurable surface device according to claim 7, characterized in that, The chalcogenide phase change materials include: germanium-antimony-tellurium, antimony sulfide, antimony selenide, antimony telluride, germanium-tellurium, or germanium-antimony-selenium-tellurium compounds; The germanium-antimony-tellurium alloy includes one or more of Ge2Sb2Te5, Ge3Sb2Te6, GeSb4Te7, and GeSb2Te4.

9. A phase compensation method for a reconfigurable metasurface device according to any one of claims 1-3, characterized in that, include: Based on the theoretical phase distribution, a metasurface structure layer with a periodic array distribution is grown on the first surface of the substrate. Detect the actual phase distribution of the metasurface structure layer; The phase distribution error between the actual phase distribution and the theoretical phase distribution is obtained; A phase compensation layer is grown 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 transition process to obtain the theoretical phase distribution; The phase compensation layer is made of a phase change material.

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