A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna

Abstract

A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna is disclosed. It adopts an electrically controlled lateral field electrode layout, spatiotemporal multiplexing drive, and a swastika-shaped compact structure. It consists of four rotationally symmetrical sub-aperture regions, with the electrodes of the four sub-aperture regions forming a swastika structure. By setting ITO electrode array A, ITO electrode array B, and metal electrodes on the same glass substrate, the lateral electric field between the electrodes drives the deflection of the liquid crystal molecules' orientation vector. This eliminates the need for COM ITO electrodes, enabling the realization of a large-aperture liquid crystal optical phased array device with low absorption, high diffraction efficiency, large-scale electrode array, and high integration.

Description

Technical Field

[0001] This invention relates to a multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna, belonging to the fields of large-aperture liquid crystal optical phased arrays, multi-user laser communication, satellite laser communication networking, MIMO spatial light modulator technology, and near-field optical field manipulation. Background Technology

[0002] Liquid crystal molecules possess optical properties that can be modulated by an electric field. By changing the electric field, the alignment of liquid crystal molecules can be adjusted, thereby altering the polarization state of light transmitted through the liquid crystal. This property makes liquid crystals a powerful tool for regulating light transmission. Since the advent of liquid crystal display technology in the 1960s, it has been widely used in the field of electronic displays, such as LCD televisions, computer monitors, and smartphone screens. With continuous improvements in liquid crystal materials and manufacturing processes, the performance of liquid crystal display technology has been continuously enhanced, laying the foundation for the expansion of optical applications of liquid crystals.

[0003] Phased array technology is a technique that achieves precise wavefront control by manipulating the phase of light waves. Traditional phased arrays consist of a large number of independent antenna elements, and the radiation beam is controlled by adjusting the phase of each element. Phased arrays have wide applications in radar, communication, and lidar. However, traditional phased arrays suffer from large size, complex manufacturing, and high power consumption, limiting their application in some fields. Therefore, researchers have begun to seek new phased array technologies to meet broader application needs. Large-aperture optical systems are optical systems with a large effective aperture. In fields such as optical communication, optical remote sensing, and laser imaging, large-aperture optical systems can improve signal receiving sensitivity and image resolution, enhancing system performance. However, traditional large-aperture optical systems are constrained by complex optical components and mechanical structures, resulting in high manufacturing and adjustment costs, and the problem of dual-layer interference in both longitudinal and transverse fields remains difficult to solve. Summary of the Invention

[0004] The technical problem solved by this invention is: in view of the limitations of traditional large-aperture optical design technology in the current technology due to structural design and interference problems, a multi-user low absorption high efficiency large-aperture liquid crystal optical phased array antenna is proposed.

[0005] The present invention solves the above-mentioned technical problem through the following technical solution:

[0006] A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna includes four sub-aperture regions that are rotationally symmetrical with respect to each other.

[0007] The sub-aperture region includes a first antireflective film, a first substrate, a liquid crystal molecule layer, a second substrate, and a second antireflective film, which are stacked sequentially from top to bottom; spacers are periodically arranged in the liquid crystal molecule layer, and the two ends of the liquid crystal molecule layer are bonded to the bottom of the first substrate and the top of the second substrate by a frame adhesive.

[0008] The first substrate includes a first glass substrate and a first PI alignment layer, with the first glass substrate disposed on the first PI alignment layer. The second substrate includes a second PI alignment layer, an ITO electrode array A, an ITO electrode array B, a metal electrode, and a second glass substrate, stacked sequentially from top to bottom. The first PI alignment layer and the second PI alignment layer are bonded to the upper and lower sides of the liquid crystal molecule layer by a frame adhesive. The metal electrode is disposed at the center of the second PI alignment layer of the second substrate. The ITO electrode array A and the ITO electrode array B form an ITO array layer, disposed below the second PI alignment layer, and the ITO array layer is mounted on the second glass substrate. The metal electrode and the ITO electrode array B form a comb-shaped electrode structure. The comb-shaped electrode structure is connected to the GND terminal of an external driving circuit through the metal electrode. The ITO electrode array A is used to apply alternating positive and negative electric fields. The ITO electrode array B of the comb-shaped electrode structure and the applied ITO electrode array A form a transverse electric field to drive the deflection of the liquid crystal molecules in the liquid crystal molecule layer.

[0009] The first antireflection film, the second antireflection film, the first glass substrate, the second glass substrate, the first PI alignment layer, and the second PI alignment layer are all aligned with both ends of the frame adhesive. The ITO electrode array B and the ITO electrode array A in the comb-shaped structure electrode are intersected in the same layer to form an ITO array layer. The width of the ITO electrode array A and the ITO electrode array B in the ITO array layer is set to 1 / 5 of the metal electrode spacing to reduce ITO absorption.

[0010] The ITO array layer is composed of phase control units, which are formed by the area surrounded by one ITO electrode array A and two adjacent ITO electrode arrays B; the first PI orientation layer and the second PI orientation layer are both preset to have an orientation angle of 90° perpendicular to the surface.

[0011] During the power-driven process, the ITO electrode array A is subjected to two positive voltages followed by one negative voltage within one voltage loading cycle, and the voltage loading is repeated according to the voltage loading cycle.

[0012] The ITO electrode array A is driven by a driver IC, which is connected to an external data bus BUS. Data distribution between the driver ICs is achieved according to the control of the external processor and a time-division multiplexing strategy.

[0013] The mounting process of the ITO electrode array A and ITO electrode array B on the second glass substrate is determined according to the design requirements of the optical phased array antenna, and they are mounted on the same glass substrate.

[0014] The resistivity of the designed metal electrode is less than that of the ITO electrode to enhance the current movement speed and improve the control refresh rate of liquid crystal molecules.

[0015] The electrode spacing between the ITO electrode arrays is reduced to increase the spatial proportion of the gradient electric field and the diffraction efficiency. The electrode spacing is determined and adjusted according to the design requirements of the gradient electric field.

[0016] The electrode widths of the array electrode A and the array electrode B are much smaller than the spacing therebetween. The fabrication processes of the array electrode A and the array electrode B are determined according to the design requirements of the phased array antenna.

[0017] The advantages of the present invention compared with the prior art are as follows:

[0018] (1) A multi-user low-absorption high-efficiency large-aperture liquid crystal optical phased array antenna provided by the present invention removes the COM ground ITO in the double-sided ITO structure of the traditional liquid crystal phased array and designs a single-layer ITO array, reducing the area of the ITO. The ITO absorption rate is reduced by at least 75%. By adopting a transverse field design, the problem of double-layer interference between the longitudinal field and the transverse field is eliminated, the electric field is pure, and the phase depression problem is significantly improved, effectively enhancing the beam pointing diffraction efficiency.

[0019] (2) The electrode widths of the array electrodes A and B of the present invention are much smaller than the electrode spacing. The fabrication of the process structure is relatively simple, including but not limited to wet method, dry method, magnetron sputtering or even numerical control engraving, which can be made at one time. The probability of secondary repair of electrode short circuit is greatly reduced, and the yield is high. By adopting an electrically controlled transverse field electrode layout, time-space multiplexing drive and a "卐"-shaped compact structure, a large-aperture liquid crystal optical phased array device with low absorption rate, high diffraction efficiency, large-scale electrode array and high integration is finally realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic cross-sectional view of the low-absorption high-efficiency large-aperture liquid crystal optical phased array antenna provided by the invention;

[0021] Figure 2 Schematic side cross-sectional view of the low-absorption high-efficiency large-aperture liquid crystal optical phased array antenna provided by the invention;

[0022] Figure 3 General design structure block diagram and drive block diagram of the liquid crystal optical phased array antenna provided by the invention;

[0023] Figure 4 Drive electrical characteristic diagram of the ITO electrode provided by the invention;

[0024] Figure 5 Schematic diagram of time-division multiplexing in a single sub-aperture region provided by the invention; Detailed Implementation

[0025] A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna is disclosed. It adopts an electrically controlled lateral field electrode layout, spatiotemporal multiplexing drive, and a swastika-shaped compact structure. It consists of four rotationally symmetrical sub-aperture regions, with the electrodes of the four sub-aperture regions forming a swastika structure. By setting ITO electrode array A, ITO electrode array B, and metal electrodes on the same glass substrate, the lateral electric field between the electrodes drives the deflection of the liquid crystal molecules' orientation vector. This eliminates the need for COM ITO electrodes, enabling the realization of a large-aperture liquid crystal optical phased array device with low absorption, high diffraction efficiency, large-scale electrode array, and high integration.

[0026] A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna, including sub-aperture regions, with four sub-aperture regions that are rotationally symmetrical with respect to each other.

[0027] The sub-aperture region includes a first antireflective film, a first substrate, a liquid crystal molecule layer, a second substrate, and a second antireflective film, which are stacked sequentially from top to bottom; spacers are periodically arranged in the liquid crystal molecule layer, and the two ends of the liquid crystal molecule layer are bonded to the bottom of the first substrate and the top of the second substrate by a frame adhesive.

[0028] The first substrate includes a first glass substrate and a first PI alignment layer, with the first glass substrate disposed on the first PI alignment layer. The second substrate includes a second PI alignment layer, an ITO electrode array A, an ITO electrode array B, a metal electrode, and a second glass substrate, stacked sequentially from top to bottom. The first PI alignment layer and the second PI alignment layer are bonded to the upper and lower sides of the liquid crystal molecule layer by a frame adhesive. The metal electrode is disposed at the center of the second PI alignment layer of the second substrate. The ITO electrode array A and the ITO electrode array B form an ITO array layer, disposed below the second PI alignment layer, and the ITO array layer is mounted on the second glass substrate. The metal electrode and the ITO electrode array B form a comb-shaped electrode structure. The comb-shaped electrode structure is connected to the GND terminal of an external driving circuit through the metal electrode. The ITO electrode array A is used to apply alternating positive and negative electric fields. The ITO electrode array B of the comb-shaped electrode structure and the applied ITO electrode array A form a transverse electric field to drive the deflection of the liquid crystal molecules in the liquid crystal molecule layer.

[0029] The first antireflective film, the second antireflective film, the first glass substrate, the second glass substrate, the first PI alignment layer, and the second PI alignment layer are all aligned with both ends of the frame adhesive. The ITO electrode array B and the ITO electrode array A in the comb-shaped structure electrode are intersected in the same layer to form an ITO array layer. The width of the ITO electrode array A and the ITO electrode array B in the ITO array layer is set to 1 / 5 of the metal electrode spacing to reduce ITO absorption.

[0030] The ITO array layer is composed of phase control units, which are the regions enclosed by one ITO electrode array A and two adjacent ITO electrode arrays B; the first PI orientation layer and the second PI orientation layer are both preset to have an orientation angle of 90° perpendicular to the plane.

[0031] During the power-driven process, the ITO electrode array A is subjected to two positive voltages followed by one negative voltage within one voltage loading cycle, and the voltage loading is repeated according to the voltage loading cycle.

[0032] The ITO electrode array A is driven by a driver IC, which is connected to an external data bus (BUS). Data distribution between the driver ICs is controlled by an external processor and uses a time-division multiplexing strategy.

[0033] The mounting process of ITO electrode array A and ITO electrode array B on the second glass substrate is determined according to the design requirements of the optical phased array antenna.

[0034] The following description, in conjunction with the accompanying drawings and preferred embodiments, provides further details:

[0035] In the current embodiment, it mainly consists of four rotationally symmetrical sub-aperture regions, and the electrodes of the four sub-aperture regions form a swastika structure. Each sub-aperture is composed of a first antireflection film, a first substrate, a liquid crystal molecule layer, a second substrate, and a second antireflection film stacked sequentially from top to bottom. ITO electrode array A and ITO electrode array B are both on the same glass substrate. The lateral electric field between the electrodes drives the liquid crystal molecule director to deflect, eliminating the need for COM ITO electrodes, reducing ITO absorption and device fabrication complexity, and improving the overall performance of the device.

[0036] like Figure 1 , Figure 2 As shown, a multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna has the following spatial structure: the first substrate includes a first glass substrate 2-1 and a first PI alignment layer 4-1; periodically arranged spacers 6 are distributed in the liquid crystal molecule layer, with sealant 5-1 at both ends to bond the upper and lower PI alignment layers; the second substrate, from top to bottom, consists of a second PI alignment layer 4-2, an ITO electrode array A 3-1, an ITO electrode array B 3-2, a metal electrode C 4-3, and a second glass substrate 2-2;

[0037] like Figure 2As shown, metal electrode C4-3 is located in the center of PI alignment layer 4, forming a "cross" structure. This metal electrode and ITO electrode B form a comb-like structure. Electrically, the comb-like electrode is connected to the GND terminal of the driving circuit through metal electrode C4-3, while ITO electrode A is subjected to alternating positive and negative electric fields. The lateral electric field formed by ITO electrodes A and B drives the deflection of the liquid crystal molecules' orientation vector. In the actual device fabrication process, the steps can be adjusted appropriately. For example, after fabricating ITO electrodes A and B, a 100nm-200nm thick "cross" metal electrode film can be deposited above the end of ITO electrode B. Subsequently, the PI alignment film is directly deposited on the entire device plane, covering ITO electrodes A and B together with the metal conductive film C. The pre-alignment angle of the PI alignment layer is 90° perpendicular to the plane. This alignment can be formed in one step using a specific alignment material, without the need for frictional alignment.

[0038] In the spatial structure, all antireflective coatings 1-1, 1-2, glass substrates 2-1 and 2-2, PI alignment layers 4-1 and 4-2, and frame adhesive 5-1 are aligned at both ends. Most importantly, in the stacked structure, there is only one layer of ITO. The widths of ITO electrode arrays A 3-1 and B 3-2 are 1 / 5 of the electrode spacing, significantly reducing ITO absorption compared to traditional designs.

[0039] An effective actual phase control unit consists of the area surrounded by one ITO electrode array A and two adjacent ITO electrode arrays B. Therefore, the additional ITO electrodes B are equivalent to a multiple increase in the number of electrodes of the driving IC, which in turn increases the aperture of the liquid crystal phase control array.

[0040] like Figure 4 As shown, a multi-user low-absorption high-efficiency large-aperture liquid crystal optical phased array antenna is characterized in that, during the power-driven process, the ITO electrode array A is applied with a negative voltage after every two positive voltages, i.e., 2 positive voltages → 1 negative voltage → 2 positive voltages → 1 negative voltage… and then the process is repeated.

[0041] In addition, such as Figure 3 As shown, a multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna is characterized by its sub-aperture region consisting of a large ITO electrode array A3-1 and an ITO electrode array B3-2. The ITO electrode array A3-1 is divided into multiple driver ICs, which are connected to a data bus (BUS). An FPGA / DSP / SOC processor controls the data router, employing a time-division multiplexing strategy to distribute data to the multiple driver ICs. The specific driving timing refresh strategy is as follows: Figure 5 As shown.

[0042] A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna, wherein ITO electrode array A, ITO electrode array B and ITO electrode array B are all on the second glass substrate 2-2.

[0043] Metal electrodes are designed with a lower resistivity than ITO electrodes to increase the current flow rate and improve the control refresh rate of the liquid crystal cell. Similar metal films and composite polymer films with higher resistivity than ITO are also included in this category.

[0044] Reducing the electrode spacing between ITO electrode arrays can effectively increase the spatial proportion of the gradient electric field and improve diffraction efficiency. The data that the electrode width is 1 / 5 of the electrode spacing is only a value in this design, and other similar designs are within the scope of protection listed here.

[0045] The electrode widths of array electrodes A and B are much smaller than the distance between them, making the fabrication process simple and beneficial for various manufacturing processes. This falls under the patent scope of the entire process from design to manufacturing.

[0046] Finally, a multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna is developed. Because the electrode widths of array electrodes A and B are proportionally smaller than the electrode spacing, the fabrication process is relatively simple. It can be fabricated in one step using processes including but not limited to wet, dry, magnetron sputtering, and even CNC engraving, which reduces the probability of secondary circuit repair and greatly improves the yield.

[0047] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0048] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna, characterized in that: It includes sub-aperture regions, with a total of 4 sub-aperture regions, and each sub-aperture region is rotationally symmetrical. The sub-aperture region includes a first antireflective film, a first substrate, a liquid crystal molecule layer, a second substrate, and a second antireflective film, which are stacked sequentially from top to bottom; spacers are periodically arranged in the liquid crystal molecule layer, and the two ends of the liquid crystal molecule layer are bonded to the bottom of the first substrate and the top of the second substrate by a frame adhesive. The first substrate includes a first glass substrate and a first PI alignment layer, with the first glass substrate disposed on the first PI alignment layer. The second substrate includes a second PI alignment layer, an ITO electrode array A, an ITO electrode array B, a metal electrode, and a second glass substrate, stacked sequentially from top to bottom. The first PI alignment layer and the second PI alignment layer are bonded to the upper and lower sides of the liquid crystal molecule layer by a frame adhesive. The metal electrode is disposed at the center of the second PI alignment layer of the second substrate. The ITO electrode array A and the ITO electrode array B form an ITO array layer, disposed below the second PI alignment layer, and the ITO array layer is mounted on the second glass substrate. The metal electrode and the ITO electrode array B form a comb-shaped electrode structure. The comb-shaped electrode structure is connected to the GND terminal of an external driving circuit through the metal electrode. The ITO electrode array A is used to apply alternating positive and negative electric fields. The ITO electrode array B of the comb-shaped electrode structure and the applied ITO electrode array A form a transverse electric field to drive the deflection of the liquid crystal molecules in the liquid crystal molecule layer.

2. The multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 1, characterized in that: The first antireflection film, the second antireflection film, the first glass substrate, the second glass substrate, the first PI alignment layer, and the second PI alignment layer are all aligned with both ends of the frame adhesive. The ITO electrode array B and the ITO electrode array A in the comb-shaped structure electrode are intersected in the same layer to form an ITO array layer. The width of the ITO electrode array A and the ITO electrode array B in the ITO array layer is set to 1 / 5 of the metal electrode spacing to reduce ITO absorption.

3. The multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 2, characterized in that: The ITO array layer is composed of phase control units, which are formed by the area surrounded by one ITO electrode array A and two adjacent ITO electrode arrays B; the first PI orientation layer and the second PI orientation layer are both preset to have an orientation angle of 90° perpendicular to the surface.

4. The multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 2, characterized in that: During the power-driven process, the ITO electrode array A is subjected to two positive voltages followed by one negative voltage within one voltage loading cycle, and the voltage loading is repeated according to the voltage loading cycle.

5. The multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 2, characterized in that: The ITO electrode array A is driven by a driver IC, which is connected to an external data bus BUS. Data distribution between the driver ICs is achieved according to the control of the external processor and a time-division multiplexing strategy.

6. The multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 2, characterized in that: The mounting process of the ITO electrode array A and ITO electrode array B on the second glass substrate is determined according to the design requirements of the optical phased array antenna, and they are mounted on the same glass substrate.

7. The multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 2, characterized in that: The resistivity of the metal electrode is designed to be lower than that of the ITO electrode in order to increase the current flow rate and improve the control refresh rate of the liquid crystal molecules.

8. A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 2, characterized in that: The electrode spacing between the ITO electrode arrays is reduced to improve the spatial proportion of the gradient electric field and the diffraction efficiency. The electrode spacing is determined and adjusted according to the design requirements of the gradient electric field.

9. A multi-user, low-absorption, high-efficiency, large-aperture liquid crystal optical phased array antenna according to claim 2, characterized in that: The electrode widths of electrode arrays A and B are much smaller than the distance between them, and the fabrication processes of electrode arrays A and B are determined according to the design requirements of the phased array antenna.

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