A high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate

Abstract

The application discloses a high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate, relates to a liquid crystal optical phased array technology, and aims to solve the problem of low transmittance of an existing liquid crystal optical phased array, and comprises an upper substrate, a liquid crystal molecule layer and a lower substrate; the upper substrate comprises an upper substrate outer surface far-infrared antireflection film, an upper substrate chalcogenide glass, an upper substrate inner surface far-infrared antireflection film, an upper common electrode and an upper alignment layer; the lower substrate comprises a lower alignment layer, a lower grating electrode, a lower substrate inner surface far-infrared antireflection film, a lower substrate chalcogenide glass, a lower substrate outer surface far-infrared antireflection film. The far-infrared high-transmittance chalcogenide glass is arranged in the upper and lower substrates, and the far-infrared high-transmittance optical antireflection film layer is plated on the upper and lower surfaces of the chalcogenide glass; the chalcogenide glass and the far-infrared high-transmittance optical antireflection film layer constitute the liquid crystal optical phased array, so that the liquid crystal optical phased array has the advantages of high transmittance, fast response speed, simple driving control and the like.

Description

Technical Field

[0001] This invention belongs to the field of space optical communication technology, and relates to a liquid crystal optical phased array technology, particularly a high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate. Background Technology

[0002] With the rapid development of infrared technology, the demand for infrared products in aerospace, modern military, and other fields is gradually shifting towards higher quality and higher precision. The demand for related products is growing rapidly, and the continuous advancement of military-civilian integration necessitates high-quality and low-cost products for military applications. Liquid crystal optical phased arrays, as an important component of lidar scanning systems, offer advantages such as small size, light weight, fast response speed, high resolution, and programmable control. The far-infrared 8-14 micrometer band is a crucial atmospheric window and the primary operating area for military infrared detectors and infrared guidance systems. Far-infrared liquid crystal optical phased array beam scanning technology, as the most advanced non-mechanical beam scanning technology, uses far-infrared liquid crystal as its functional material, extending phased beam scanning technology to the 8-14 micrometer far-infrared band and solving problems such as rapid angle switching and high-precision pointing in far-infrared lidar.

[0003] Patent application number 202211505305.9 discloses a liquid crystal optical phased array device with laser power tolerance and its fabrication method. The phased array device, from bottom to top, comprises: a substrate, an array electrode layer, an alignment layer, a liquid crystal layer, another alignment layer, a conductive layer, and another substrate. Subwavelength array aperture structures are provided on each electrode of the array electrode layer and on the conductive layer. This invention cleverly bypasses conventional technical approaches by fabricating a sub-laser wavelength anti-reflection array structure on the surface of the conductive layer film, achieving high transmittance performance in the required laser band, thereby overcoming the technical shortcomings of current liquid crystal phased array beam deflection devices in far-infrared applications. This technical approach not only effectively reduces the heat accumulation of laser energy inside the device but also greatly improves the light energy utilization rate, thus enhancing the overall functionality of the device. This invention patent cleverly bypasses the conventional approach of developing new optically highly transparent conductive materials to reduce the absorption of light energy by the conductive layer thin film substrate itself. Instead, it achieves high transmittance performance in the required laser band by preparing a sub-laser wavelength anti-reflection array structure on the surface of the conductive layer thin film, thereby making up for the technical shortcomings of current liquid crystal phased array beam deflection devices in the far-infrared band application.

[0004] Similar to the aforementioned invention patents, the application bands of liquid crystal optical phased arrays in the prior art are mainly in the near-infrared (1.064 μm, 1.55 μm) and mid-infrared (3-5 μm). However, in practical thermal imaging infrared optical systems and infrared guidance systems, the transmittance of liquid crystal optical phased arrays in these bands is still relatively low, and their applicability is largely limited by their low transmittance. How to achieve far-infrared liquid crystal optical phased arrays with high transmittance performance is a common pursuit of researchers. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of low transmittance of existing liquid crystal optical phased arrays, and to provide a high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate, thereby improving the overall transmittance of the phased array.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0007] A high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate includes: an upper substrate, a liquid crystal molecular layer, and a lower substrate.

[0008] The upper substrate comprises, from top to bottom: a far-infrared anti-reflection film on the outer surface of the upper substrate, a chalcogenide glass on the upper substrate, a far-infrared anti-reflection film on the inner surface of the upper substrate, an upper common electrode, and an upper alignment layer;

[0009] The lower substrate, from top to bottom, includes: a lower alignment layer, a lower grating electrode, a far-infrared anti-reflection film on the inner surface of the lower substrate, a chalcogenide glass on the lower substrate, and a far-infrared anti-reflection film on the outer surface of the lower substrate.

[0010] The liquid crystal molecule layer is located between the upper substrate and the lower substrate, and the upper substrate and the lower substrate are sealed at their edges.

[0011] Furthermore, the upper substrate and the lower substrate are sealed and encapsulated using frame adhesive.

[0012] Furthermore, spacers are sprayed into the frame adhesive, and the upper and lower substrates are supported by the spacers.

[0013] Furthermore, the size of the spacer is determined based on the birefringence of the liquid crystal material. The spacer is used to control the thickness of the liquid crystal molecular layer, enabling the liquid crystal molecular layer to achieve a 2π phase shift.

[0014] Furthermore, the orientation direction of the orientation film layer in the upper orientation layer is the same as that in the lower orientation layer.

[0015] Furthermore, the lower grating electrode is fabricated using photolithography and / or dry etching processes.

[0016] Furthermore, during the photolithography process, an SU-8 protective layer is spin-coated onto the surface of the lower grating electrode on the lower substrate.

[0017] The beneficial effects of this invention are as follows:

[0018] 1. In this invention, chalcogenide glass with high far-infrared transmittance is disposed in the upper and lower substrates, and two parallel far-infrared high transmittance optical antireflection film layers are deposited on the upper and lower surfaces of the chalcogenide glass. The chalcogenide glass and the far-infrared high transmittance optical antireflection film layers constitute a liquid crystal optical phased array. Based on the modulation principle of a transmissive liquid crystal spatial light modulator, the one-dimensional deflection angle of the emitted light is controlled by changing the thickness of the liquid crystal layer and the loading voltage of the array electrodes, so that the liquid crystal optical phased array has the advantages of high transmittance, fast response speed and simple driving control.

[0019] 2. In this invention, the upper and lower substrates are sealed and encapsulated with a frame adhesive, and spacers are sprayed in the frame adhesive. The spacers in the frame adhesive support the upper and lower substrates, 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 can be controlled by the size of the spacers, and finally the liquid crystal molecular layer achieves a 2π phase shift.

[0020] 3. In this invention, the lower grating electrode is made by etching process, and SU-8 protective layer is spin-coated on the surface of the lower grating electrode on the lower substrate to effectively protect the lower grating electrode from corrosion during alkaline developing process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the grating electrode distribution in this invention;

[0023] The reference numerals in the attached figures are as follows: 1-far-infrared anti-reflection film on the outer surface of the upper substrate, 2-chalcogenide glass on the upper substrate, 3-far-infrared anti-reflection film on the inner surface of the upper substrate, 4-upper common electrode, 5-upper alignment layer, 6-liquid crystal molecule layer, 7-spacer, 8-lower alignment layer, 9-lower grating electrode, 10-far-infrared anti-reflection film on the inner surface of the lower substrate, 11-chalcogenide glass on the lower substrate, 12-far-infrared anti-reflection film on the outer surface of the lower substrate. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0025] Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides a high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate. From the perspective of device design, chalcogenide glass with high far-infrared transmittance is selected, and far-infrared anti-reflection films are deposited on both sides of the substrate to improve the overall transmittance of the phased array and meet the relevant performance requirements of the overall phased array.

[0028] The high transmittance far-infrared liquid crystal optical phased array includes an upper substrate, a liquid crystal molecular layer 6, and a lower substrate. The liquid crystal molecular layer 6 is located between the upper substrate and the lower substrate. The edges of the upper substrate and the lower substrate are sealed and encapsulated, and then aligned, bonded, and cured, thereby forming a plurality of liquid crystal arrays filled with liquid crystal between the upper substrate and the lower substrate.

[0029] The upper substrate comprises, from top to bottom: an outer surface far-infrared anti-reflection film 1, a chalcogenide glass 2, an inner surface far-infrared anti-reflection film 3, an upper common electrode 4, and an upper alignment layer 5.

[0030] The lower substrate comprises, from top to bottom: a lower alignment layer 8, a lower grating electrode 9, a far-infrared anti-reflection film 10 on the inner surface of the lower substrate, a chalcogenide glass 11 on the lower substrate, and a far-infrared anti-reflection film 12 on the outer surface of the lower substrate.

[0031] The upper substrate chalcogenide glass 2 and the lower substrate chalcogenide glass 11 are a general term for a class of inorganic glasses formed by introducing other relatively weak electronegativity elements such as As and Ga as the basic components of group VIA elements S, Se and Te. They have advantages such as small thermal coefficient, wide spectral transmission range (0.8-14μm), excellent chemical stability and continuously adjustable performance.

[0032] The upper substrate and the lower substrate are sealed and encapsulated with frame adhesive.

[0033] Spacers 7 are sprayed into the frame adhesive, and the upper and lower substrates are supported by the spacers 7.

[0034] The size of spacer 7 is determined based on the birefringence of the liquid crystal material. Spacer 7 is used to control the thickness of the liquid crystal molecular layer, so that the liquid crystal molecular layer can achieve a 2π phase shift.

[0035] The orientation direction of the orientation film layer of the upper orientation layer 5 is the same as the orientation direction of the orientation film layer of the lower orientation layer 8.

[0036] Because the lower grating electrode 9 has a micrometer-level width and high precision, it needs to be fabricated using processes such as photolithography and dry etching. However, the developer used in the etching process is generally alkaline, and chalcogenide glass dissolves in alkaline developer at a rate of tens of nanometers per second. The lower grating electrode 9 will also be corroded during the alkaline developer process. Therefore, during photolithography, an SU-8 protective layer is spin-coated onto the surface of the lower grating electrode 9 on the lower substrate to prevent corrosion by the developer before subsequent photolithography and dry etching processes. During the etching process, residual photoresist that has not reacted with the mercury lamp is first stripped with oxygen. Then, the oxygen process parameters are modified to etch the SU-8 protective layer. Finally, chlorine gas is introduced into the cavity to etch the array electrodes.

[0037] like Figure 2 The diagram shows the distribution of optical phased array grating electrodes for a high-transmittance far-infrared liquid crystal based on a chalcogenide glass substrate. The array electrodes apply periodic voltages to the liquid crystal to ensure that the phase difference modulation of the incident light is consistent between adjacent liquid crystal electronically controlled regions.

[0038] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of the claims of the invention.

Claims

1. A high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate, comprising: The upper substrate, the liquid crystal molecular layer (6), and the lower substrate are characterized in that: the upper substrate comprises, from top to bottom, a far-infrared anti-reflection film (1) on the outer surface of the upper substrate, a chalcogenide glass (2) on the upper substrate, a far-infrared anti-reflection film (3) on the inner surface of the upper substrate, an upper common electrode (4), and an upper alignment layer (5); the lower substrate comprises, from top to bottom, a lower alignment layer (8), a lower grating electrode (9), a far-infrared anti-reflection film (10) on the inner surface of the lower substrate, a chalcogenide glass (11) on the lower substrate, and a far-infrared anti-reflection film (12) on the outer surface of the lower substrate; the liquid crystal molecular layer (6) is located between the upper substrate and the lower substrate, and the upper substrate and the lower substrate are sealed and encapsulated at their edges.

2. The high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate as described in claim 1, characterized in that: The upper substrate and the lower substrate are sealed and encapsulated with frame adhesive.

3. The high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate as described in claim 2, characterized in that: Spacers (7) are sprayed into the frame adhesive, and the upper substrate and the lower substrate are supported by the spacers (7).

4. The high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate as described in claim 3, characterized in that: The size of the spacer (7) is determined according to the birefringence of the liquid crystal material. The spacer (7) is used to control the thickness of the liquid crystal molecular layer (6) so that the liquid crystal molecular layer can achieve a 2π phase shift.

5. The high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate as described in claim 1, characterized in that: The orientation direction of the orientation film layer of the upper orientation layer (5) is the same as that of the orientation film layer of the lower orientation layer (8).

6. The high-transmittance far-infrared liquid crystal optical phased array based on a chalcogenide glass substrate as described in claim 1, characterized in that: The lower grating electrode (9) is fabricated using photolithography and dry etching processes.

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