CN110568610A - An electrostatic dynamic adjustable reflective zoom metasurface lens and its preparation method - Google Patents

Abstract

the invention discloses an electrostatic dynamically adjustable reflective zoom super-surface lens and a preparation method thereof, belonging to the field of dynamically adjustable super-surfaces and comprising the following steps: the device comprises a glass substrate, an ITO film, an antenna, an air gap, a supporting structure, a silicon nitride film, a silicon frame and a gold back plate; the antenna is used for regulating and controlling the phase of incident light; the air gap is used for providing a space for deformation of the gold back plate, and the maximum deformation degree of the gold back plate is one third of the thickness of the air gap; the support structure is used for forming an air gap; the gold back plate is used as a positive electrode, the ITO film is used as a negative electrode to form an electrostatic MEMS system, and the gold back plate is used as a movable electrode and used for realizing different-degree convex deformation under the regulation and control of voltage; the geometric parameters of the antenna are obtained according to the initial focal length, the incident light wavelength and the generalized Snell's law required by the super-surface lens; the invention can adjust the focal length of the static super-surface lens by changing the voltage between the ITO film and the gold back plate, thereby increasing the yield.

Description

An electrostatic dynamic adjustable reflective zoom metasurface lens and its preparation method

technical field

The invention belongs to the field of dynamically adjustable metasurfaces, and more specifically relates to an electrostatic dynamic adjustable reflective zoom metasurface lens and a preparation method thereof.

Background technique

As a new type of two-dimensional material, the metasurface can regulate the amplitude, phase, polarization, and vortex of electromagnetic waves. It has the characteristics of small size, thin thickness and multifunctionality, and the metasurface is compatible with CMOS technology. It has broad application prospects.

Static metasurface lens is easy to introduce errors due to the growth, exposure and etching processes in the preparation process, which makes the final focal length and design focal length offset and cause errors. This error reduces the yield of the metasurface lens.

Micro-electromechanical systems (MEMS) usually use liquid crystal, graphene, machinery, thermal change, static electricity, etc. to achieve dynamic control of devices on a small scale. After a period of development, they have become more and more mature and can be applied to micro-optical devices. Micro-opto-electromechanical systems (MEMOS) are realized on the surface, and the technology of MEMS and metasurface are compatible with each other. Therefore, the combination of metasurface and MEMS to realize dynamically tunable metasurface is bound to be the trend of future development.

Common dynamic regulation methods usually include liquid crystal type, graphene type, mechanical type, thermal variable type, etc. Among them, the liquid crystal type realizes dynamic regulation by adjusting the voltage to change the direction of the liquid crystal. The disadvantage is that the response speed of the liquid crystal is low, usually in milliseconds. ; The graphene formula realizes dynamic control by adjusting the Fermi level of graphene. The disadvantage is that graphene is not compatible with traditional CMOS technology, and it is difficult to produce on a large scale under the existing industrial foundation, and the cost of graphene is relatively high; The mechanical arm stretches the deformable medium to achieve dynamic regulation. The disadvantage is that the additional mechanical device occupies a large volume. The thermal variable method uses materials with different thermal expansion coefficients to control temperature changes to achieve dynamic regulation of the structure. The disadvantage is that the cooling time of the system structure is difficult. The control and the slow speed lead to the limitation of the control speed, and it will generate large thermal noise in the infrared band, which cannot be applied.

To sum up, the uncontrollable focal length of static metasurface lenses will lead to low yield, and the existing dynamic control technology has disadvantages such as low response speed, high cost, immature production technology, large volume occupation, and limited applicable wavelength bands.

Contents of the invention

In view of the defects of the prior art, the purpose of the present invention is to provide an electrostatic dynamic adjustable reflective zoom metasurface lens and its preparation method, aiming to solve the problem of low yield caused by the non-adjustable focal length of the existing static metasurface lens The problem.

To achieve the above object, the present invention provides an electrostatic dynamic adjustable reflective zoom metasurface lens, comprising: glass substrate, ITO (Indium Tin Oxide, tin-doped indium oxide) film, antenna, air gap, support structure, Silicon nitride film, silicon frame and gold backplane;

The ITO film is located above the glass substrate, the antenna is located in the middle above the ITO film, and the support structure is located outside the antenna. The ITO film and the gold backplane are separated to form an air gap, and the position for applying voltage is set on the ITO film; silicon nitride The film is over the air gap, the silicon frame is over the silicon nitride film, and the gold backplane is over the silicon frame;

The antenna is used to adjust the phase of the incident light; the air gap is used to provide space for the deformation of the gold backplane, and the maximum deformation of the gold backplane is one third of the thickness of the air gap; the support structure is used to form the air gap; the silicon nitride film and The silicon frame is used to support the gold backplane; the gold backplane is used as the positive electrode and the ITO film is used as the negative electrode to form an electrostatic MEMS system. The geometric parameters of are obtained according to the initial focal length required by the metasurface lens, the wavelength of the incident light and the generalized Snell's law;

Preferably, the antenna is metal or silicon or titanium dioxide or germanium;

Preferably, the shape of the antenna is disc-shaped or square-shaped or circular-shaped according to the polarization-independent characteristic;

Preferably, the shape of the antenna is strip-shaped or elliptical-cylindrical or V-shaped according to polarization-related characteristics;

Preferably, the incident light is in the infrared band;

On the other hand, based on the electrostatic dynamic adjustable reflective zoom metasurface lens provided above, the present invention proposes its preparation method, including:

(1) Utilize the magnetron sputtering method to grow an ITO thin film above the glass substrate;

(2) Utilize the electron beam evaporation method to evaporate gold on the ITO thin film surface;

(3) The gold surface obtained in step (2) is sequentially passed through uniform glue, exposure, development, etching and redevelopment to prepare a gold antenna array structure;

(4) The surface of the sample sheet obtained in step (3) is sequentially passed through uniform glue, exposure and development to obtain a hollow insulating support structure, and expose the area where the gold antenna is located and the position where the voltage is applied to the ITO film;

(5) Evaporate a silicon nitride film on the support structure, and deposit a silicon frame on the top of the silicon nitride film to form a silicon frame silicon nitride film window;

The opening window of the silicon frame is facing the gold antenna, and the size of the opening window is greater than or equal to the size of the gold antenna array; the silicon nitride film has no effect on the light field of the incident light;

(6) Evaporate a gold film above the silicon nitride film window of the silicon frame to form a movable electrode as a gold backplane;

(7) Fix the silicon nitride film and the support structure to complete the fabrication of the electrostatic dynamic adjustable reflective zoom metasurface lens.

Preferably, step (3) includes:

(3.1) Spin-coat the first photoresist on the gold surface obtained in step (2) to form a photoresist surface;

(3.2) exposing the photoresist surface obtained in step (3.1) through electron beam exposure equipment to the gold antenna array structure layout to form a patterned sample;

(3.3) develop the sample with pattern, and obtain the sample of photoresist layer with gold antenna array structure;

(3.4) Etching on the sample sheet of the photoresist layer with the gold antenna array structure to form a sample sheet with the gold antenna array structure;

(3.5) Remove the photoresist on the sample sheet with the gold antenna array structure using a developing solution.

Step (4) specifically includes:

(4.1) Spin-coat the second photoresist on the sample surface with the gold antenna array obtained in step (3);

(4.2) Carry out exposure treatment to the sample piece that is spin-coated with the second photoresist;

If the second photoresist is a negative photoresist, the non-exposed area is the area where the gold antenna is located and the position where the voltage is applied to the ITO film; otherwise, the exposed area is the area where the gold antenna is located and the position where the voltage is applied to the ITO film;

(4.3) Developing the sample after exposure in step (4.2) to obtain a hollow insulating support structure;

The second photoresist is a negative photoresist.

Preferably, the second photoresist is SU-8 photoresist.

Through the above technical solutions conceived in the present invention, compared with the prior art, the following can be obtained

Beneficial effect:

(1) In the preparation process of the static metasurface lens, it is difficult to avoid errors in processes such as growth, exposure, and etching, which affect the optical performance of the metasurface lens and cause errors in the focal length of the metasurface lens. The present invention proposes an electrostatic dynamic method based on MEMS. The adjustable reflective zoom metasurface lens can solve the problem that the focal length of the static metasurface lens cannot be adjusted. The finished product caused by the unqualified focal length of the lens can be adjusted by changing the voltage between the ITO film and the gold backplane. Compliance with standards, therefore, improves the overall yield.

(2) For non-integrated optical systems, due to the error of the focal length of the metasurface lens, the metasurface lens needs to be adjusted accordingly in the installation and adjustment of the optical system, resulting in an increased difficulty in the installation and adjustment of the optical system. Even if the present invention exists The error of the focal length of the metasurface lens can also be overcome by adjusting the voltage between the ITO film and the gold backplane, and there is no need to make corresponding adjustments in the adjustment of the optical system.

(3) For the integrated optical system, it is often impossible to adjust the position of the metasurface lens, so the focal length error produced in the preparation process of the static metasurface lens finally affects the entire integrated optical system, causing system errors. The present invention can adjust the ITO thin film and The voltage between the gold backplates changes the focal length, corrects the focal length error, and ultimately reduces the system error.

Description of drawings

Fig. 1 is the structural cross-sectional view of electrostatic dynamic adjustable reflective zoom metasurface lens provided by the present invention;

Fig. 2 is a top view of the gold antenna array structure provided by the present invention;

Fig. 3 is the focal change diagram of the electrostatic dynamic adjustable reflective zoom metasurface lens provided by the present invention under different voltages;

Fig. 4 is the preparation flowchart of the electrostatic dynamic adjustable reflective zoom metasurface lens provided by the present invention;

Fig. 5 is a schematic diagram of the preparation of the electrostatic dynamic adjustable reflective zoom metasurface lens provided by the present invention;

Fig. 6 is a working schematic diagram of the electrostatic dynamic adjustable reflective zoom metasurface lens provided by the present invention;

In all the drawings, the same reference numerals represent the same elements or structures, wherein: 11-glass substrate; 12-ITO film; 13-gold antenna array structure; 14-first photoresist; 15-support structure ; 20-air gap; 21-silicon nitride film; 22-silicon frame; 23-gold backplane.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Example 1

As shown in Figure 1, the present embodiment provides an electrostatic dynamic adjustable reflective zoom metasurface lens, comprising: glass substrate 11, ITO film 12, gold antenna 13, support structure 15, air spacer 20, nitrided Silicon film 21, silicon frame 22 and gold backplane 23;

The ITO film 12 is located above the glass substrate 11, the gold antenna 13 is located in the middle above the ITO film 12, the support structure 15 is located outside the gold antenna 13, and the ITO film 12 and the gold backplane 23 are separated to form the Above the air gap 20, the ITO film 12 is provided with a position for applying voltage; the silicon nitride film 21 is located above the air gap 20, the silicon frame 22 is located above the silicon nitride film 21, and the gold backplane 23 is located above the silicon frame 22;

The gold antenna 13 is used to adjust the phase of the incident light; the air gap 20 is used to provide a space for the deformation of the gold back plate 23, and the maximum deformation degree of the gold back plate 23 is one-third of the thickness of the air gap 20; the support structure 15 is used for The air gap 20 is formed; the silicon nitride film 21 and the silicon frame 22 are used to support the gold back plate 23; the gold back plate 23 is used as a positive electrode and the ITO film 12 is used as a negative electrode to form an electrostatic MEMS system, and the gold back plate 23 It is an active electrode, which is used to realize different degrees of convex deformation under the regulation of voltage; the geometric parameters of the antenna are obtained according to the initial focal length required by the metasurface lens, the wavelength of incident light, and the generalized Snell's law.

In this embodiment, the thickness of the ITO film 12 is 100nm, the thickness of the gold antenna 13 is 100nm, the unit period width of the gold antenna array structure is 2um, the thickness of the air gap 20 is 2um, and the thickness of the gold backplane 23 is 200nm.

A reflective metasurface structure is usually composed of an antenna, an intermediate medium, and a reflective metal backplane. The antenna is usually an array of structural units with different duty ratios with a certain period, and different duty ratios provide different phase mutation values. , so that the entire array produces different phase profiles, and finally realizes the focusing of light.

Common antenna shapes are usually disc-shaped, square, and circular according to polarization-independent characteristics, and are usually strip-shaped, elliptical cylindrical, and V-shaped according to polarization-dependent characteristics, as shown in Figure 2. In this embodiment, Considering the polarization-independent characteristics, the disk structure is adopted. In fact, according to the realized function, it is not limited to this shape structure, and other structures can still be used; antenna materials usually include metals such as gold, silver and aluminum, or dielectrics such as silicon, titanium dioxide and Germanium, etc., different types of materials can be selected according to the wavelength of the incident light. In this embodiment, the incident light is considered to be in the infrared band, and the material of the antenna is metal gold. According to the actual application, the incident light is not limited to the infrared band, and other bands can also be used. Adopting this structure is not limited to this material, and other materials can also realize the function of adjusting the phase of incident light.

Considering that the gold backplane 23 needs to be deformed under voltage control, the intermediate medium is air, that is, the air gap 20 .

The gold back plate 23 is used as a reflector, but the incident light is reflected. According to the dynamic control characteristics of the reflective metasurface structure, under different voltages, the gold back plate 23 acts as a movable electrode to the direction of the fixed electrode of the ITO film 12 to different degrees. The deformation of the reflected light field changes the phase, thereby changing the focus position.

According to the finite time domain difference calculation method, the radius and phase relationship of the 13-unit structure of the gold antenna are calculated, and the focal length is set to 50um, and the wavelength of the incident monochromatic light is 3.83um. According to the generalized Snell’s law, each unit of today’s array is determined. The radius of the structure disk.

According to the electrostatic field and structural mechanics finite element algorithm simulation, the protrusion deformation generated by the gold back plate 23 under different voltages is obtained, so that the phase distribution of the reflected light field generated by the gold back plate 23 under different voltages changes, and finally the super The focal length of the surface lens. It can be seen from Fig. 3 that the wavelength of the normal incident light is 3.83um, and the focal length of the metasurface lens produced by the metasurface lens changes from 50um to 67um under the voltage of 0-190V for any linearly polarized light.

Based on the above electrostatic dynamic adjustable reflective zoom metasurface lens, this embodiment discloses the flow chart of the preparation method shown in Figure 4 and the preparation method shown in Figure 5, including:

S101 growing an ITO thin film 12 with a thickness of 100 nm on the glass substrate 11 by using a magnetron sputtering method;

S102 vapor-depositing a 50nm gold thin film 13 on the surface of the ITO thin film 12 by using an electron beam evaporation method;

S103 Spin-coat the first photoresist 14 on the surface of the gold thin film 13 obtained in step S102 to form a photoresist surface;

S104 exposing the gold antenna array structure layout to the photoresist surface obtained in step S103 by electron beam exposure equipment to form a patterned sample;

The exposure area is shown in the shaded area of step S104 in Figure 5; the specific parameters of the gold antenna array structure are determined by the wavelength of the incident light, the required focal length and the generalized Snell's law;

S105 develops the patterned sample to obtain a photoresist layer sample with a gold antenna array structure; as shown in Figure 5 step S105, 14 is recorded as the photoresist pattern after the development process;

S106 etches on the sample sheet of the photoresist layer with the gold antenna array structure to form a sample sheet with the gold antenna array structure; etched away to form a gold antenna array structure;

S107 utilizes developing solution to remove the photoresist on the sample with the gold antenna array structure; as shown in Figure 5 step S107, there is a photoresist 14 on the surface of the sample with the gold antenna array structure, which is removed, leaving the gold antenna array structure;

S108 Spin-coat SU-8 photoresist on the sample surface with gold antenna array obtained in step S107; as shown in Figure 5 step S108, SU-8 photoresist is a relatively thick negative photoresist with insulation , can be used to make the supporting structure 15 of the microbridge;

The present invention can adopt SU-8 photoresist to make support structure 15, but it is not limited to adopt SU-8 photoresist, can prepare the photoresist of support structure 15 all can, convenient expression, can use this kind of photoresist collectively referred to as the second photoresist;

S109 Expose the sample coated with SU-8 photoresist; since SU-8 is a negative resist, the non-exposed area will be removed in the subsequent development process, and the exposed area will be retained. Therefore, the non-exposed area is the area where the gold antenna is located and the position where the voltage is applied to the ITO film; the exposed area is shown in the oblique shaded area of step S109 in Figure 5;

S110 develops the sample after exposure in step S109 to obtain a hollow insulating support structure; as shown in step S110 in FIG. 5 , after development, the photoresist area that has not been exposed in step S110 in FIG. The photoresist area is retained to form an insulating support structure 15 as shown in the figure, so as to realize the air gap 20 required for the deformation of the gold backplane 23; at the same time, the photoresist 15 on the part of the edge of the ITO film 12 is also removed, so that It is exposed to facilitate feeding the ITO electrodes;

S201 Evaporate a silicon nitride film 21 on the silicon substrate, use a silicon etching liquid to etch the silicon nitride film 21 on the side without the silicon nitride film 21 until the silicon nitride film 21 is exposed, and remove the silicon by etching Form the silicon frame 22 in the middle area of the silicon frame, and finally form the silicon nitride film window of the silicon frame; The window is facing the gold antenna 13, and the size of the window is greater than or equal to the size of the gold antenna 13 array. In other words, the silicon frame 22 is obtained by etching the middle area of a whole silicon crystal. After etching, the silicon nitride film below 21 exposure; the silicon nitride film 21 is thin and has high transmittance to a wide spectrum, and has no influence on the light field of the transmitted light. Therefore, the silicon nitride film 21 is usually used as a transparent window under a wide spectrum; the silicon nitride film is nitrided The silicon thin film window is mainly used as the substrate and supporting structure for the growth of the gold thin film 23 in the present invention, and has no influence on the incident light field;

S202 vapor-deposits a gold film above the silicon nitride film window of the silicon frame to form a movable electrode as the gold back plate 23; as shown in step S202 of FIG. The upper surface of the silicon nitride film 21 and the silicon frame 22 is used as an active electrode; at the same time, the gold film on the silicon nitride film window of the silicon frame is used as a reflector to reflect incident light; and on the gold back plate 23 and the ITO film 12 electrode When a voltage is applied between them, the gold back plate 23 will protrude and deform in the direction of the ITO thin film electrode, and according to the magnitude of the voltage, a convex mirror with different curvatures will be formed, so that the phase of the reflected light field will change to varying degrees, thereby realizing the change of the focal point ;

S203 fixes the silicon nitride film 21 and the supporting structure 15 to complete the manufacture of the electrostatic dynamic adjustable reflective zoom metasurface lens.

Based on the preparation method of the electrostatic dynamic adjustable reflective zoom metasurface lens proposed by the present invention, as shown in Figure 6, after the parallel light incident from the 01 direction is vertically incident on the gold antenna array structure, it is determined according to the generalized Snell's law The gold antenna array structure produces a phase profile with a spherical wave shape, allowing light to converge. When no voltage is applied, the gold backplane is in a horizontal state. After the incident light passes through the gold antenna array, it converges along the direction of the solid line 02, and after being reflected by the gold backplane 23, it exits along the direction of the solid line 03 according to Snell’s law. Convergence occurs again through the gold antenna array structure 13, and finally converges to one point along the direction of the solid line 04; when a voltage is applied, the gold backplane 23 protrudes and deforms along the dotted line shown in Figure 6 toward the direction of the ITO film motor. The light is uninterrupted along the direction 01. After being converged by the gold antenna array, it is incident on the raised gold back plate 23 along the dotted line 05. After reflection, due to the diffusion effect of the convex mirror, it emerges along the dotted line 06 according to Snell’s law. Converge again through the gold antenna array, and finally converge to a point along the direction of the dotted line 07. When the voltage is different, the degree of deformation produced by the gold back plate 23 is different, and when realized as reflection, it will have different effects on the reflection phase distribution of the light, and realize the control of the focus.

In summary, during the preparation process of the static metasurface lens, it is difficult to avoid errors in processes such as growth, exposure, and etching, which affect the optical performance of the metasurface lens and cause an error in the focal length of the metasurface lens. The present invention proposes a MEMS-based electrostatic The dynamic adjustable reflective zoom metasurface lens can solve the problem that the focal length of the static metasurface lens cannot be adjusted. The finished product caused by the unqualified focal length of the lens can be adjusted by changing the voltage between the ITO film 12 and the gold backplane 23. The focal length of the lens makes it conform to the standard, thus, improving the overall yield.

For non-integrated optical systems, due to the error of the focal length of the traditional metasurface lens, the metasurface lens needs to be adjusted accordingly in the installation and adjustment of the optical system, resulting in increased difficulty in the installation and adjustment of the optical system. The error of the focal length of the surface lens can also be overcome by adjusting the voltage between the ITO film and the gold backplane, and there is no need to make corresponding adjustments in the adjustment of the optical system. For integrated optical systems, it is often impossible to adjust the position of the metasurface lens, so the focal length error generated during the preparation of the static metasurface lens will eventually affect the entire integrated optical system, causing system errors. The present invention can adjust the ITO film and gold backplane The voltage between changes the focal length, corrects the focal length error, and finally reduces the system error.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (8)

1. An electrostatic dynamic adjustable reflective zoom metasurface lens is characterized in that, comprising: glass substrate (11), ITO film (12), antenna, support structure (15), air space (20), nitrogen Si film (21), silicon frame (22) and gold backplane (23); The ITO film (12) is located above the glass substrate (11), the antenna is located in the middle above the ITO film (12), the support structure is located outside the antenna, and the ITO film (12) ) and the gold back plate (23) are separated to form the air gap (20), and the position for applying voltage is set on the ITO film (12); the silicon nitride film (21) is located in the air gap (20), the silicon frame (22) is positioned above the silicon nitride film (21), and the gold backplane (23) is positioned above the silicon frame (22); The antenna is used for incident light phase regulation; the air gap (20) is used to provide a deformation space for the gold back plate (23), and the maximum deformation degree of the gold back plate (23) is the air gap ( 20) one-third of the thickness; the support structure is used to form the air gap (20); the silicon nitride film (21) and the silicon frame (22) are used to support the gold backplane ( 23); the gold back plate (23) is used as a positive electrode and the ITO thin film (12) is used as a negative electrode to form an electrostatic MEMS system, and the gold back plate (23) is a movable electrode, which is used for under voltage regulation Different degrees of convex deformation are realized; the geometric parameters of the antenna are obtained according to the initial focal length required by the metasurface lens, the wavelength of incident light and the generalized Snell's law. 2. The electrostatic dynamic adjustable reflective zoom metasurface lens according to claim 1, wherein the antenna is metal or silicon or titanium dioxide or germanium. 3. electrostatic dynamic adjustable reflective zoom metasurface lens according to claim 1 or 2, is characterized in that, the shape of described antenna is disk-shaped or square or annular according to polarization-independent characteristic, and described antenna According to the polarization-dependent characteristics, the shape is bar-shaped or elliptical-cylindrical or V-shaped. 4. The electrostatic dynamically adjustable reflective zoom metasurface lens according to any one of claims 1 to 3, wherein the incident light is in the infrared band. 5. based on the preparation method of electrostatic dynamic adjustable reflective zoom metasurface lens claimed in claim 1, it is characterized in that, comprising: (1) Utilize the magnetron sputtering method to grow an ITO thin film (12) above the glass substrate (11); (2) Utilize the electron beam evaporation method to evaporate gold on the ITO film (12) surface; (3) The gold surface obtained in step (2) is sequentially passed through uniform glue, exposure, development, etching and redevelopment to prepare a gold antenna array structure; (4) The surface of the sample sheet obtained in step (3) is sequentially passed through gluing, exposure and development to obtain a hollow insulating support structure, and the area where the gold antenna (13) is located and the position where the voltage is applied to the ITO film (12) are exposed; (5) Evaporating a silicon nitride film (21) above the support structure, and depositing a silicon frame (22) above the silicon nitride film (21) to form a silicon frame silicon nitride film window; The opening window of the silicon frame (22) is facing the gold antenna (13), and the size of the opening window is greater than or equal to the size of the gold antenna (13) array; the silicon nitride film (21) has no influence on the light field of the incident light; (6) Evaporate a gold film on the silicon frame silicon nitride film window to form a movable electrode as a gold back plate (23); (7) Fixing the silicon nitride film (21) and the support structure (15) to complete the fabrication of the electrostatic dynamic adjustable reflective zoom metasurface lens. 6. preparation method according to claim 5, is characterized in that, described step (3) comprises: (3.1) Spin-coat the first photoresist (14) on the gold surface obtained in step (2) to form a photoresist surface; (3.2) exposing the photoresist surface obtained in step (3.1) through electron beam exposure equipment to the gold antenna array structure layout to form a patterned sample; (3.3) develop the sample with pattern, and obtain the sample of photoresist layer with gold antenna array structure; (3.4) Etching on the sample sheet of the photoresist layer with the gold antenna array structure to form a sample sheet with the gold antenna array structure; (3.5) Remove the photoresist on the sample sheet with the gold antenna array structure using a developing solution. 7. according to the preparation method described in claim 5 or 6, it is characterized in that, described step (4) comprises: (4.1) Spin-coat the second photoresist on the sample surface with the gold antenna array obtained in step (3); (4.2) Carry out exposure treatment to the sample piece that is spin-coated with the second photoresist; If the second photoresist is a negative photoresist, then the non-exposed area is the position where the gold antenna is located and the ITO film applied voltage; otherwise, the exposure The area is the area where the gold antenna is located and the position where the voltage is applied to the ITO film; (4.3) Developing the sample after exposure in step (4.2) to obtain a hollow insulating support structure. 8. The preparation method according to claim 7, wherein the second photoresist is SU-8 photoresist.