Mid-infrared liquid crystal optical phased array based on CIO conductive film and its preparation method

Abstract

The present invention discloses a mid-infrared liquid crystal optical phased array based on CIO conductive film and a preparation method thereof. This invention relates to liquid crystal optical phased array technology and aims to address the low transmittance problem of existing liquid crystal optical phased arrays in the mid-infrared band. The invention comprises: an upper substrate assembly, a liquid crystal molecular layer, and a lower substrate assembly; the upper substrate assembly comprising: a mid-infrared antireflection film on the outer surface of the upper substrate, an upper substrate, a mid-infrared antireflection film on the inner surface of the upper substrate, an upper CIO common electrode layer, and an upper orientation layer; and the lower substrate assembly comprising: a lower orientation layer, a lower CIO electrode layer, a mid-infrared antireflection film on the inner surface of the lower substrate, a lower substrate, and a mid-infrared antireflection film on the outer surface of the lower substrate. Compared to common liquid crystal optical phased arrays based on ITO conductive film, the liquid crystal optical phased array based on CIO conductive film and mid-infrared antireflection film in this application has higher transmittance in the mid-infrared band and can effectively reduce light loss of the entire liquid crystal phased array.

Description

Technical Field

[0001] The present invention belongs to the field of spatial optical communication technology and relates to liquid crystal optical phased array technology, and in particular to a mid-infrared liquid crystal optical phased array based on CIO conductive film and a preparation method thereof. Background Art

[0002] With the rapid development of infrared technology, the demand for infrared products in fields such as aerospace and modern military is gradually shifting towards higher quality and higher precision, resulting in a rapid increase in demand for related products. The continuous advancement of military-civilian integration has led to the demand for high-quality and low-cost products when infrared technology is applied to military applications. Liquid crystal optical phased arrays, as a key component of lidar scanning systems, offer advantages such as small size, light weight, fast response speed, high resolution, and programmable control. The mid-infrared 3-5 micron band is a critical atmospheric window and the primary operating region for military infrared detectors and infrared guidance systems. Mid-infrared liquid crystal optical phased arrays, the most advanced non-mechanical beam scanning technology, utilize mid-infrared liquid crystal as its functional material. This technology can extend phased beam scanning technology to the 3-5 micron mid-infrared band, addressing the challenges of fast angle switching and high-precision pointing in far-infrared lidar.

[0003] The invention patent application with application number 202211505305.9 discloses a liquid crystal optical phased array device that can withstand laser power and a preparation method thereof. The phased array device includes, from bottom to top,: a substrate, an array electrode layer, an orientation layer, a liquid crystal layer, an orientation layer, a conductive layer, and a substrate; a sub-wavelength array hole structure is provided on each electrode of the array electrode layer and on the conductive layer.

[0004] The invention patent application with application number 202311244043.X also discloses a liquid crystal optical phased array with a high filling ratio, which includes a first anti-reflection film, a first substrate, a first liquid crystal molecule layer, a second substrate, a second liquid crystal molecule layer, a third substrate and a second anti-reflection film stacked in sequence from top to bottom. The first substrate includes a first glass substrate, a first ITO electrode layer and a first PI orientation layer. The second substrate includes a second PI orientation layer, an ITO electrode array A, a second glass substrate, an ITO electrode array B and a third PI orientation layer arranged from top to bottom. The third substrate includes a fourth PI orientation layer, a second ITO electrode and a third glass substrate distributed in sequence from top to bottom. The first PI, second PI, third PI and fourth PI orientation layers constitute PI orientation layers respectively. The electrode arrays A and B are located on the front and back sides of the second glass substrate and are cross-distributed in space.

[0005] As in the above-mentioned invention patent, the conductive films in existing liquid crystal optical phased arrays mostly still use indium tin oxide (ITO) transparent conductive films. According to research, the transmittance of ITO conductive films is closely related to the thickness of the film. The optical transmittance of ITO conductive films of different thicknesses is different. Even an ITO film with a thickness of 50nm has a transmittance of less than 90% in the near-infrared band. In the existing technology, there are also new conductive film materials. For example, some people have proposed to use the high transmittance advantage of graphene in the infrared band to replace the traditional ITO film, but the electrode lithography of graphene is a very difficult problem; some people have proposed to use organic polymer conductive films (such as ethylenedioxythiophene / sodium polyvinyl sulfonate (PEDOT:PSS)) to prepare conductive films, but its high transmittance is also mainly limited to the visible light band. Therefore, it is necessary to propose a new conductive film material so that the film material prepared by it can have a higher transmittance in the mid-infrared band. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem of low transmittance of existing liquid crystal optical phased arrays in the mid-infrared band, provide a mid-infrared liquid crystal optical phased array based on CIO conductive film and its preparation method, and improve the transmittance and multi-beam capability of the overall phased array in the mid-infrared band.

[0007] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0008] A mid-infrared liquid crystal optical phased array based on a CIO conductive film comprises: an upper substrate assembly, a liquid crystal molecular layer, and a lower substrate assembly arranged in sequence from top to bottom;

[0009] The upper substrate assembly includes: a mid-infrared anti-reflection film on the outer surface of the upper substrate, an upper substrate, a mid-infrared anti-reflection film on the inner surface of the upper substrate, an upper CIO common electrode layer, and an upper alignment layer, which are arranged in sequence from top to bottom;

[0010] The lower substrate assembly includes: a lower orientation layer, a lower CIO electrode layer, a mid-infrared anti-reflection film on the inner surface of the lower substrate, a lower substrate, and a mid-infrared anti-reflection film on the outer surface of the lower substrate, which are arranged in sequence from top to bottom.

[0011] Furthermore, it also includes a frame glue located outside the liquid crystal molecule layer, and the upper substrate assembly and the lower substrate assembly are sealed and packaged by the frame glue.

[0012] Furthermore, the frame glue is doped with spacers, and the upper substrate assembly and the lower substrate assembly are supported by the spacers.

[0013] Furthermore, the spacer is used to control the thickness of the liquid crystal molecular layer. The size of the spacer is determined according to the birefringence difference of the liquid crystal material in the liquid crystal molecular layer, and the product of the birefringence difference of the liquid crystal material in the liquid crystal molecular layer and the thickness of the liquid crystal molecular layer is greater than the wavelength of the working electromagnetic wave used.

[0014] Furthermore, the alignment direction of the alignment film layer of the upper alignment layer is opposite to the alignment direction of the alignment film layer of the lower alignment layer.

[0015] Furthermore, the lower CIO electrode layer includes a plurality of CIO grating electrodes arranged at intervals, each CIO grating electrode is connected to the communication driver chip on the lower substrate, and the voltage on each CIO grating electrode is independently regulated by the communication driver chip.

[0016] Furthermore, the voltage applied to the CIO grating electrode is regulated by the communication driver chip, which changes the electric field distribution in the space where the liquid crystal molecular layer is located, drives the liquid crystal molecules in the liquid crystal molecular layer to rotate, and causes the phase delay of light to change when passing through the liquid crystal molecules.

[0017] Furthermore, the CIO grating electrode is manufactured by wet method, dry method, magnetron sputtering or CNC engraving.

[0018] Furthermore, the lower substrate includes four sub-aperture areas that are independently controlled from each other.

[0019] A method for preparing a mid-infrared liquid crystal optical phased array based on a CIO conductive film comprises the following steps:

[0020] Step 1, cleaning;

[0021] Clean the upper and lower substrates to be plated;

[0022] Step 2, coating;

[0023] Depositing a mid-infrared anti-reflection film on the outer surface of the upper substrate and a mid-infrared anti-reflection film on the outer surface of the lower substrate on the back of the upper substrate and the lower substrate respectively;

[0024] Depositing a mid-infrared anti-reflection film on the inner surface of the upper substrate and a mid-infrared anti-reflection film on the inner surface of the lower substrate on the front surfaces of the upper substrate and the lower substrate respectively;

[0025] Depositing an upper CIO common electrode layer and a lower CIO electrode layer on the mid-infrared antireflection film on the inner surface of the upper substrate and the mid-infrared antireflection film on the inner surface of the lower substrate respectively;

[0026] Step 3, photolithography;

[0027] The pattern on the mask is transferred to the lower substrate coated with the film layer using photoresist as a medium, and a layer of photoresist pattern having the same pattern as the mask is formed on the lower substrate;

[0028] Step 4, etching;

[0029] The areas on the lower substrate not protected by the photoresist are etched away using an etching process to obtain a CIO grating electrode; a plurality of CIO grating electrodes arranged at intervals form a lower CIO electrode layer;

[0030] Step 5, preparing an alignment layer;

[0031] Coating polyimide on the upper substrate with the prepared electrodes, and preparing an upper liquid crystal alignment layer by rubbing alignment or photo-alignment;

[0032] Coating polyimide on the lower substrate with the prepared electrodes, and preparing a lower liquid crystal alignment layer by rubbing alignment or photo-alignment;

[0033] Setting the alignment directions of the upper liquid crystal alignment layer on the upper substrate and the lower liquid crystal alignment layer on the lower substrate to be antiparallel;

[0034] Step 6, pressing the box and filling the wafer;

[0035] The upper substrate and the lower substrate are attached together using a sealant, and spacers are added to the sealant. Then, liquid crystal is poured into the area between the sealant, the upper substrate, and the lower substrate using the siphon effect to form a liquid crystal layer.

[0036] The beneficial effects of the present invention are as follows:

[0037] 1. In the present invention, a CIO transparent conductive film is used as the conductive film, and a mid-infrared anti-reflection film is provided on the upper and lower substrates. Compared with the common liquid crystal optical phased array based on ITO conductive film, the liquid crystal optical phased array based on CIO conductive film and mid-infrared anti-reflection film of the present application has a higher transmittance in the mid-infrared band (the transmittance of ITO conductive film in the mid-infrared is generally not higher than 30%, while the transmittance of the CIO conductive film of the present application in the mid-infrared is more than 50%), which can effectively reduce the light loss of the entire liquid crystal phased array.

[0038] 2. This invention not only introduces CIO conductive film to replace traditional ITO conductive film as the phased array power supply film layer, but also uses a mid-infrared high-transmittance substrate to replace ordinary glass as the base, and adds mid-infrared high-transmittance optical anti-reflection film layers on the upper and lower surfaces of the substrate. At the same time, it uses a new mid-infrared high-transmittance liquid crystal material. Compared with traditional liquid crystal phased arrays based on ITO conductive film, this can effectively reduce optical losses in the mid-infrared. At the same time, multiple independently controlled areas can be integrated into a single device, which can be used by multiple users simultaneously. Mid-infrared liquid crystal optical phased arrays have the advantages of high transmittance, fast response speed, simple drive control, and high integration in the mid-infrared band.

[0039] 3. In the present invention, based on the modulation principle of the transmissive liquid crystal spatial light modulator, the one-dimensional deflection angle of the outgoing light is controlled by changing the thickness of the liquid crystal layer and the loading voltage of the array electrode, so that the liquid crystal optical phased array has the advantages of high transmittance, fast response speed, and simple driving control.

[0040] 4. In the present invention, the upper and lower substrates are sealed and packaged by frame glue, and spacers are sprayed in the frame glue. The upper and lower substrates are supported by the spacers in the frame glue, so that the size of the spacers can be adjusted according to the refractive index of the liquid crystal material. The thickness of the liquid crystal molecular layer of the array liquid crystal device is then controlled by the size of the spacers, and finally the product of the birefringence difference of the liquid crystal molecular layer and the thickness of the liquid crystal layer is made to be greater than the wavelength of the working electromagnetic wave used. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic cross-sectional view of the structure of the present invention;

[0042] Figure 2 This is a schematic diagram of the lower substrate grating electrode structure of the present invention;

[0043] Among them, the figure markings are: 1-mid-infrared anti-reflection film on the outer surface of the upper substrate; 2-upper substrate; 3-mid-infrared anti-reflection film on the inner surface of the upper substrate; 4-upper CIO common electrode layer; 5-upper orientation layer; 6-liquid crystal molecule layer; 7-spacer; 8-lower orientation layer; 9-CIO grating electrode; 10-mid-infrared anti-reflection film on the inner surface of the lower substrate; 11-lower substrate; 12-mid-infrared anti-reflection film on the outer surface of the lower substrate; 13-communication driver chip; 14-frame glue. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0045] Therefore, based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0046] Example 1:

[0047] This embodiment provides a multi-user mid-infrared liquid crystal optical phased array based on CIO conductive film. From a device design perspective, CIO conductive film is selected as the power supply film layer, sapphire with high mid-infrared transmittance is used as the substrate material, and mid-infrared anti-reflection coating is applied on both sides of the substrate to improve the transmittance of the entire phased array and enhance the related performance of the entire phased array.

[0048] The multi-user mid-infrared liquid crystal optical phased array includes: an upper substrate assembly, a liquid crystal molecular layer 6 and a lower substrate assembly. The liquid crystal molecular layer 6 is located between the upper substrate assembly and the lower substrate assembly. The edges of the upper substrate assembly and the lower substrate assembly are sealed and encapsulated, aligned, bonded and cured, and spacers 7 are added to adjust the thickness, thereby forming a liquid crystal layer with a stable thickness between the upper substrate assembly and the lower substrate assembly.

[0049] The upper substrate assembly includes, from top to bottom, a mid-infrared anti-reflection film 1 on the outer surface of the upper substrate, an upper substrate 2, a mid-infrared anti-reflection film 3 on the inner surface of the upper substrate, an upper CIO common electrode layer 4 and an upper orientation layer 5.

[0050] The lower substrate assembly includes, from top to bottom, a lower orientation layer 8, a lower CIO electrode layer 9, a mid-infrared anti-reflection film 10 on the inner surface of the lower substrate, a lower substrate 11, and a mid-infrared anti-reflection film 12 on the outer surface of the lower substrate.

[0051] The upper substrate assembly and the lower substrate assembly are sealed and packaged by a sealant 14. Spacers 7 are doped in the sealant 14. The upper substrate assembly and the lower substrate assembly are supported by the spacers 7. The size of the spacers 7 is determined according to the birefringence of the liquid crystal material, and the product of the birefringence difference of the liquid crystal material in the liquid crystal molecular layer 6 and the thickness of the liquid crystal molecular layer 6 is greater than the wavelength of the working electromagnetic wave used; the spacers 7 are used to control the thickness of the liquid crystal molecular layer so that the liquid crystal molecular layer achieves a phase shift of 2π.

[0052] The orientation direction of the alignment film of the upper alignment layer 5 is opposite to that of the alignment film of the lower alignment layer 8 , and the alignment can be performed by friction or photo-anchoring during the preparation process.

[0053] The lower CIO electrode layer includes multiple CIO grating electrodes 9 spaced apart. Each CIO grating electrode 9 is connected to a communication driver chip 13 on the lower substrate 11. The voltage applied to each CIO grating electrode 9 is independently controlled by the communication driver chip 13. The communication driver chip 13 regulates the voltage applied to the CIO grating electrodes 9, changing the electric field distribution in the space surrounding the liquid crystal layer 6. This drives the liquid crystal molecules in the liquid crystal layer 6 to rotate, causing the phase delay of light to change as it passes through the liquid crystal molecules. Furthermore, the CIO grating electrodes 9 can be manufactured using methods such as wet processing, dry processing, magnetron sputtering, or CNC engraving.

[0054] In order to achieve the control of the mid-infrared 3-5 micron band, the CIO grating electrode 9 structure should also reach a micron-level width. Taking the use of negative photoresist and dry etching process to prepare the CIO grating electrode 9 as an example, a CIO layer is first coated on the lower substrate 11 coated with an anti-reflection film through various coating methods, and photoresist is spin-coated on the lower substrate 11. A mask with a corresponding pattern is used for mercury lamp exposure. After exposure, the exposed photoresist needs to be removed by etching. The developer used in the etching process is generally alkaline. The CIO film will dissolve in the alkaline developer at a dissolution rate of tens of nanometers per second. The CIO grating electrode 9 will be corroded during the development process of the alkaline developer. Therefore, during the photolithography process, an SU-8 protective layer is spin-coated on the surface of the lower CIO electrode layer 9 of the lower substrate 11 to prevent erosion by the developer, and then the subsequent photolithography and dry etching processes are carried out. During the etching process, oxygen is first used to strip off the remaining photoresist that has not reacted with the mercury lamp, then the SU-8 protective layer is etched with oxygen, and finally chlorine gas is passed into the cavity to etch out the array electrode.

[0055] The lower substrate 11 includes four sub-aperture areas that are independently controlled.

[0056] Example 2:

[0057] This embodiment provides a method for preparing a mid-infrared liquid crystal optical phased array based on a CIO conductive film, which includes the following steps:

[0058] Step 1, cleaning;

[0059] The upper substrate 2 and the lower substrate 11 to be plated are cleaned.

[0060] To ensure the adhesion and smoothness of the film, the substrate to be coated must be cleaned before the coating process. This cleaning process primarily involves UV cleaning and ultrasonic cleaning. Only after the substrate is clean can the coating process begin.

[0061] Step 2, coating;

[0062] Depositing a mid-infrared anti-reflection film 1 on the outer surface of the upper substrate and a mid-infrared anti-reflection film 12 on the outer surface of the lower substrate on the back surfaces of the upper substrate 2 and the lower substrate 11 respectively;

[0063] Depositing a mid-infrared anti-reflection film 3 on the inner surface of the upper substrate and a mid-infrared anti-reflection film 10 on the inner surface of the lower substrate on the front surfaces of the upper substrate 2 and the lower substrate 11 respectively;

[0064] An upper CIO common electrode layer 4 and a lower CIO electrode layer are deposited on the mid-infrared antireflection film 3 on the inner surface of the upper substrate and the mid-infrared antireflection film 10 on the inner surface of the lower substrate, respectively.

[0065] When depositing corresponding film layers on substrates, magnetron sputtering can be used for preparation. Magnetron sputtering uses the action of gas glow discharge to generate ions. Under the action of the electric field in the cavity, the positive ions bombard the target material to be sputtered and exchange energy with the target atoms. The atoms or molecules on the target surface gain enough energy to escape the surface and deposit on the substrate to form a thin film.

[0066] Step 3, photolithography;

[0067] The pattern on the mask is transferred to the lower substrate 11 coated with the film layer using photoresist as a medium, and a layer of photoresist pattern having the same pattern as the mask is formed on the lower substrate 11.

[0068] After the above film is deposited, the required device pattern needs to be formed on the lower substrate 11. That is, a photolithography machine is used to transfer the pattern on the mask to the substrate coated with the film using photoresist as a medium, and finally a layer of photoresist pattern with the same pattern as the mask is left on the substrate.

[0069] Step 4, etching;

[0070] The areas on the lower substrate 11 that are not protected by the photoresist are etched away using an etching process to obtain CIO grating electrodes; a plurality of CIO grating electrodes 9 arranged at intervals form a lower CIO electrode layer.

[0071] After photolithography and development, a photoresist pattern with a mask pattern is formed on the lower substrate 11. An etching process is then used to remove the areas not protected by the photoresist, forming an array of electrodes. Taking plasma etching as an example, an ion source provides charged ions, and the electric field within the reaction chamber provides energy to the plasma, allowing it to bombard as much of the material to be etched as possible, thus etching the film layer.

[0072] Step 5, preparing an alignment layer;

[0073] Polyimide is coated on the upper substrate 2 with the electrodes prepared, and an upper liquid crystal alignment layer 5 is prepared by rubbing alignment or photo-alignment.

[0074] Polyimide is coated on the lower substrate 11 with the electrodes prepared, and a lower liquid crystal alignment layer 8 is prepared by rubbing alignment or photo-alignment.

[0075] The alignment directions of the upper liquid crystal alignment layer 5 on the upper substrate 2 and the lower liquid crystal alignment layer 8 on the lower substrate 11 are set to be antiparallel.

[0076] The purpose of an alignment agent is to align liquid crystal molecules, making them adjustable. Alignment agents are divided into parallel and vertical alignment agents. A polyimide alignment agent is applied to a pretreated substrate by spin coating. The polyimide film is then baked to cyclize and form polymer chains, enhancing the order of the molecular structure and providing anchoring for the liquid crystal molecules during subsequent alignment. Once the alignment film is formed, the rubbing alignment process can be performed. A nap roller is used to create grooves that anchor the liquid crystal molecules, ultimately forming effective alignment grooves on the alignment film.

[0077] Step 6, pressing the box and filling the wafer;

[0078] The upper substrate 2 and the lower substrate 11 are attached to each other using a sealant 14 , and spacers 7 are added to the sealant 14 . Then, liquid crystal is poured into the area between the sealant 14 , the upper substrate 21 and the lower substrate 11 using the siphon effect to form a liquid crystal layer.

[0079] After alignment is complete, the next step is the cell-forming process. This process includes applying sealant and pressing the cell. The purpose of applying sealant is to use sealant 14 to fix the relative positions of the upper substrate 2 and the lower substrate 11, and to use spacers 7 to control the thickness of the liquid crystal layer.

[0080] Siphon or vacuum filling is commonly used for crystal filling. Siphon filling uses the siphon principle to draw liquid crystal into the liquid crystal cell and is often used for filling cells with a smaller liquid crystal layer. Vacuum filling involves placing the liquid crystal cell in a vacuum chamber, extracting the air from the liquid crystal layer, and then using a syringe to drip liquid crystal into the filling port. After the liquid crystal is degassed, air is slowly added to the chamber, using the pressure difference to fill the liquid crystal into the cell.

[0081] The last step is to make circuit connections. According to the designed control circuit, the prepared liquid crystal phased array is connected to the control circuit using a soft tape line.

[0082] Those skilled in the art will appreciate that the embodiments described herein are intended to aid the reader in understanding the principles of the present invention, and it should be understood that the scope of the present invention is not limited to such specific descriptions and embodiments. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A mid-infrared liquid crystal optical phased array based on CIO conductive film, characterized by: It comprises an upper substrate assembly, a liquid crystal molecule layer (6) and a lower substrate assembly which are arranged in sequence from top to bottom; The upper substrate assembly comprises: a mid-infrared anti-reflection film (1) on the outer surface of the upper substrate, an upper substrate (2), a mid-infrared anti-reflection film (3) on the inner surface of the upper substrate, an upper CIO common electrode layer (4), and an upper orientation layer (5) arranged in sequence from top to bottom; The lower substrate assembly comprises: a lower orientation layer (8), a lower CIO electrode layer, a mid-infrared anti-reflection film (10) on the inner surface of the lower substrate, a lower substrate (11), and a mid-infrared anti-reflection film (12) on the outer surface of the lower substrate, which are arranged in sequence from top to bottom; It also includes a frame glue (14) located outside the liquid crystal molecule layer (6), and the upper substrate assembly and the lower substrate assembly are sealed and packaged by the frame glue (14); The frame glue (14) is doped with spacers (7), and the upper substrate assembly and the lower substrate assembly are supported by the spacers (7); The spacer (7) is used to control the thickness of the liquid crystal molecule layer (6). The size of the spacer (7) is determined according to the birefringence difference of the liquid crystal material in the liquid crystal molecule layer (6), and the product of the birefringence difference of the liquid crystal material in the liquid crystal molecule layer (6) and the thickness of the liquid crystal molecule layer (6) is greater than the wavelength of the working electromagnetic wave used.

2. The mid-infrared liquid crystal optical phased array based on a CIO conductive film according to claim 1, characterized in that: The orientation direction of the orientation film layer of the upper orientation layer (5) is opposite to the orientation direction of the orientation film layer of the lower orientation layer (8).

3. The mid-infrared liquid crystal optical phased array based on a CIO conductive film according to claim 1, characterized in that: The lower CIO electrode layer includes a plurality of CIO grating electrodes (9) arranged at intervals, each CIO grating electrode (9) is connected to a communication drive chip (13) on the lower substrate (11), and the voltage on each CIO grating electrode is independently regulated by the communication drive chip (13).

4. The mid-infrared liquid crystal optical phased array based on a CIO conductive film according to claim 1, characterized in that: The voltage applied to the CIO grating electrode (9) is regulated by the communication driver chip (13), thereby changing the electric field distribution in the space where the liquid crystal molecule layer (6) is located, driving the liquid crystal molecules in the liquid crystal molecule layer (6) to rotate, and causing the phase delay of light to change when passing through the liquid crystal molecules.

5. The mid-infrared liquid crystal optical phased array based on a CIO conductive film according to claim 3, characterized in that: The CIO grating electrode (9) is manufactured by wet method, dry method, magnetron sputtering or CNC engraving.

6. The mid-infrared liquid crystal optical phased array based on a CIO conductive film according to claim 1, characterized in that: The lower substrate (11) includes four sub-aperture areas that are independently controlled from each other.

7. The method for preparing a mid-infrared liquid crystal optical phased array based on a CIO conductive film according to any one of claims 1 to 6, wherein: The following steps are involved: Step 1, cleaning; Cleaning the upper substrate (2) and the lower substrate (11) to be plated; Step 2, coating; Depositing a mid-infrared anti-reflection film (1) on the outer surface of the upper substrate and a mid-infrared anti-reflection film (12) on the outer surface of the lower substrate on the back surfaces of the upper substrate (2) and the lower substrate (11), respectively; Depositing a mid-infrared anti-reflection film (3) on the inner surface of the upper substrate and a mid-infrared anti-reflection film (10) on the inner surface of the lower substrate on the front surfaces of the upper substrate (2) and the lower substrate (11), respectively; Depositing an upper CIO common electrode layer (4) and a lower CIO electrode layer on the mid-infrared antireflection film (3) on the inner surface of the upper substrate and the mid-infrared antireflection film (10) on the inner surface of the lower substrate, respectively; Step 3, photolithography; The pattern on the mask is transferred to a lower substrate (11) coated with a film layer using photoresist as a medium, and a layer of photoresist pattern having the same pattern as the mask is formed on the lower substrate (11); Step 4, etching; The areas on the lower substrate (11) not protected by the photoresist are etched away using an etching process to obtain a CIO grating electrode; a plurality of CIO grating electrodes (9) arranged at intervals form a lower CIO electrode layer; Step 5, preparing an alignment layer; Coating polyimide on the upper substrate (2) on which the electrode is prepared, and preparing an upper orientation layer (5) by means of rubbing orientation or photo-orientation; Polyimide is coated on the lower substrate (11) on which the electrode is prepared, and a lower orientation layer (8) is prepared by friction orientation or photo-orientation; The orientation directions of the upper orientation layer (5) on the upper substrate (2) and the lower orientation layer (8) on the lower substrate (11) are set to be antiparallel; Step 6, pressing the box and filling the wafer; The upper substrate (2) and the lower substrate (11) are bonded together using a frame glue (14), and spacers (7) are added to the frame glue (14); and then liquid crystal is injected into the area between the frame glue (14), the upper substrate (2), and the lower substrate (11) using a siphon effect to form a liquid crystal layer.

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