Spatial light modulator, driving method, free-space optical antenna, device and system

Abstract

The present application relates to the technical field of free-space optical communications. Disclosed are a spatial light modulator, a driving method, a free-space optical antenna, a device and a system. The spatial light modulator comprises a first substrate, a first electrode, a liquid crystal layer, a second electrode and a second substrate; the first electrode is a planar electrode, and the second electrode comprises a plurality of sub-electrodes spaced apart from each other, the plurality of sub-electrodes being successively spaced apart from each other from inside to outside around one center. When different driving voltages are respectively applied to the first electrode and the sub-electrodes, a liquid crystal material in the liquid crystal layer flips under the action of an electric field, such that the liquid crystal material has different equivalent dielectric constants, and the spatial light modulator can adjust the light intensity and phase of an incident light beam, so as to modulate different types of light beams, thereby realizing adaptive switching of light beam types, especially realizing adaptive switching of different types of light beams in pin beams, improving the anti-turbulence capability, and improving the stability of communication links.

Description

Spatial light modulators, driving methods, free space optical antennas, devices and systems

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411931349.7, filed on December 24, 2024, entitled "Spatial Light Modulator, Driving Method, Free Space Optical Antenna, Device and System", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of free-space optical communication technology, and in particular to spatial optical modulators, driving methods, free-space optical antennas, devices and systems. Background Technology

[0004] Free-space optical (FSO) communication is a wireless transmission method based on laser communication. Compared with traditional radio frequency (RF) wireless technologies, it has advantages such as large bandwidth, no spectrum application requirements, and no electromagnetic interference. Despite these significant advantages, FSO communication is susceptible to turbulence during transmission through atmospheric channels, leading to issues such as intensity fluctuations and power attenuation. Since the types of beams with higher yields may differ depending on the turbulence intensity, current FSO communication devices typically output a fixed type of beam, resulting in low turbulence resistance and impacting the stability of the communication link. Summary of the Invention

[0005] This application provides a spatial light modulator, driving method, free space optical antenna, device, and system to achieve adaptive switching of beam types, improve anti-turbulence capability, and enhance the stability of communication links.

[0006] In a first aspect, embodiments of this application provide a Spatial Light Modulator (SLM), which includes: a first substrate, a first electrode, a liquid crystal layer, a second electrode, and a second substrate arranged sequentially, such that the SLM is configured as a liquid crystal SLM. Furthermore, the first electrode is a planar electrode, and the second electrode includes a plurality of sub-electrodes spaced apart from each other, arranged sequentially from the inside out around a center. Thus, when different driving voltages are applied to the first electrode and the sub-electrodes, the liquid crystal material in the liquid crystal layer flips under the influence of an electric field, resulting in different equivalent dielectric constants. This allows the SLM to adjust the intensity and phase of an incident light beam to modulate different types of light beams, achieving adaptive switching of beam types. In particular, it can adaptively switch between different types of beams in a sharp beam, improving anti-turbulence capability and enhancing the stability of the communication link.

[0007] One possible implementation is that the plurality of sub-electrodes include non-closed ring electrodes to accommodate the needs of different types of beams in a sharp beam.

[0008] In one possible implementation, the plurality of sub-electrodes are all non-closed ring electrodes, with an opening formed between the two ends of each sub-electrode. The openings of the plurality of sub-electrodes face the same direction, which simplifies the implementation of the sub-electrodes, thereby reducing design complexity and production costs. Alternatively, the openings of the plurality of sub-electrodes can be arranged in a sequentially rotating manner from the inside out, which also simplifies the implementation of the sub-electrodes, thereby reducing design complexity and production costs.

[0009] One possible implementation is that the plurality of sub-electrodes include closed-loop electrodes to accommodate the needs of different types of beams in the sharp beam.

[0010] One possible implementation is that the plurality of sub-electrodes include a combination of non-closed ring electrodes and closed ring electrodes to accommodate the needs of different types of beams in the sharp beam.

[0011] One possible implementation is that at least some of the sub-electrodes have the same width, reducing design complexity and production costs. For example, each sub-electrode may have the same width, or some sub-electrodes may have different widths, some may have the same width, or all sub-electrodes may have different widths.

[0012] One possible implementation involves arranging multiple sub-electrodes at equal intervals, which can uniformly distribute the sub-electrodes, optimize the layout, further reduce design difficulty, and lower production costs.

[0013] One possible implementation is that the sub-electrode has a shape including one or a combination of square, rectangular, circular, and elliptical shapes. This configuration allows the sub-electrode shape to follow the shape of the SLM, thus making it suitable for beams of different types and angles of incidence.

[0014] One possible implementation also includes a driving circuit, which is connected to multiple sub-electrodes respectively. The driving circuit is used to output different driving voltages to each sub-electrode so that each sub-electrode has an electric field of different intensity with respect to the first electrode. This allows the SLM to adjust the intensity and phase of the incident beam to modulate different types of beams, especially different types of beams in a sharp beam.

[0015] In one possible implementation, the sub-electrode is a non-closed ring electrode, and the driving circuit is connected to both ends of each sub-electrode respectively. The driving circuit is used to output the same driving voltage to both ends of the same sub-electrode to modulate the needle-shaped beam.

[0016] In one possible implementation, the sub-electrode is a non-closed ring electrode, and the driving circuit is connected to both ends of each sub-electrode respectively. The driving circuit is used to output different driving voltages to both ends of the same sub-electrode to modulate a vortex beam.

[0017] Secondly, this application provides a driving method for an SLM (Solid State Liquid Crystal Laminate). The SLM includes a first substrate, a first electrode, a liquid crystal layer, a second electrode, and a second substrate arranged sequentially. The first electrode is a planar electrode, and the second electrode includes a plurality of sub-electrodes spaced apart from each other, arranged sequentially from the inside to the outside around a center. Furthermore, the method includes applying different driving voltages to each sub-electrode and applying a reference voltage to the first electrode. This arrangement allows for different electric fields of varying intensities between each sub-electrode and the first electrode, enabling the SLM to adjust the intensity and phase of an incident light beam to modulate different types of light beams, particularly different types of beams within a sharp beam.

[0018] In one possible implementation, the sub-electrode is a non-closed ring electrode, and the driving circuit is connected to both ends of the same sub-electrode respectively. The above-mentioned application of driving voltage to the sub-electrode includes: applying the same driving voltage to both ends of the same sub-electrode respectively to modulate a needle-shaped beam.

[0019] In one possible implementation, the sub-electrode is a non-closed ring electrode, and the driving circuit is connected to both ends of the same sub-electrode respectively. The above-mentioned application of driving voltage to the sub-electrode includes: applying different driving voltages to both ends of the same sub-electrode respectively to modulate a vortex beam.

[0020] In one possible implementation, the sub-electrode is a non-closed ring electrode, and the driving circuit is connected to both ends of the same sub-electrode respectively. The method further includes: applying the same driving voltage to each sub-electrode to modulate a Gaussian beam.

[0021] In one possible implementation, the sub-electrode is a closed loop electrode, and the driving circuit is connected to both ends of each sub-electrode respectively. The above-mentioned application of driving voltage to the sub-electrode includes: applying different driving voltages to each sub-electrode respectively to modulate a needle-shaped beam.

[0022] In one possible implementation, the sub-electrode is a closed loop electrode, and the driving circuit is connected to both ends of each sub-electrode respectively. The method further includes: applying the same driving voltage to each sub-electrode to modulate a Gaussian beam.

[0023] Thirdly, this application provides an FSO antenna, which includes an optical lens and an SLM, wherein the SLM is disposed at the front end of the optical lens. The SLM is the SLM used in the first aspect or in the embodiments thereof.

[0024] Fourthly, this application provides an FSO communication device, which includes a light source, a signal processing module, and an FSO antenna, wherein the FSO antenna is disposed at the rear end of the light source and the signal processing module. The FSO antenna is the FSO antenna described in the third aspect or in the embodiments of the third aspect.

[0025] Fifthly, this application provides an FSO communication system, which includes an optical transmitting device and an optical receiving device, wherein the optical transmitting device or the optical receiving device includes an FDO communication device. The FSO communication device is the FSO communication device described in the third aspect or in the embodiments of the third aspect.

[0026] Furthermore, the technical effects of the corresponding solutions in the third to fifth aspects can be referenced to the technical effects that can be obtained by the corresponding solutions in the first and second aspects, and the repetitions will not be detailed. Attached Figure Description

[0027] Figure 1 shows the FSO communication system in an embodiment of this application;

[0028] Figure 2 is a schematic diagram of the intensity and phase of a Gaussian beam, a needle beam, and a vortex beam;

[0029] Figure 3A is a top view of an SLM structure in an embodiment of this application;

[0030] Figure 3B is a top view of a second electrode structure in an embodiment of this application;

[0031] Figure 3C is a top view of the first electrode in an embodiment of this application;

[0032] Figure 4A is a schematic cross-sectional view of the structure along the AA' direction in Figure 3A;

[0033] Figure 4B is a schematic cross-sectional view of the structure along the BB' direction in Figure 3A;

[0034] Figure 5 is a top view of another embodiment of the second electrode in this application.

[0035] Figure 6A is a top view of another SLM structure in an embodiment of this application;

[0036] Figure 6B is a top view of another SLM structure in an embodiment of this application;

[0037] Figure 6C is a top view of another SLM structure in an embodiment of this application;

[0038] Figure 7 is a schematic diagram of the driving voltage applied to the second electrode in an embodiment of this application;

[0039] Figure 8 is a schematic diagram of the second electrode in the prior art SLM;

[0040] Figure 9 is a schematic diagram of the light intensity of the beam modulated by the SLM in the embodiment of this application and the SLM in the prior art.

[0041] Figure 10 is a schematic diagram of a simulation result in an embodiment of this application;

[0042] Figure 11A illustrates another top view of the SLM in an embodiment of this application;

[0043] Figure 11B illustrates another top view of the second electrode in an embodiment of this application.

[0044] Figure 12 illustrates, by way of example, a schematic diagram of the second electrode being loaded with a driving voltage in an embodiment of this application;

[0045] Figure 13 is a schematic diagram of the light intensity of the beam modulated by the SLM in the embodiment of this application and the SLM in the prior art.

[0046] Figure 14 is a schematic diagram of another simulation result in an embodiment of this application.

[0047] Reference numerals: 100 - Optical transmitting device; 110 - FSO communication device; 111 - FSO antenna; 200 - Optical receiving device; 310 - First substrate; 320 - Second substrate; 330 - First electrode; 340 - Second electrode; 350 - Liquid crystal layer; 341 / 342 / 343 / 344 / 345 - Sub-electrodes; W1 / W2 / W3 / W4 / W5 - Width; D1 / D2 / D3 / D4 - Spacing; GK - Aperture; 10 - Pixel electrode. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "multiple" can be understood as "at least two". Furthermore, it should be understood that in the description of this application, terms such as "first" and "second" are used only for distinguishing purposes and should not be construed as indicating or implying relative importance, nor as indicating or implying order.

[0049] It should be noted that the same reference numerals in the accompanying drawings of this application denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms expressing position and direction described in this application are illustrative based on the accompanying drawings, but may be modified as needed, and all modifications are included within the scope of protection of this application. The accompanying drawings of this application are for illustrating relative positional relationships only and do not represent actual scale.

[0050] The spatial light modulator (SLM) in this embodiment can be applied to an FSO communication system. For example, the SLM can be mainly applied to the FSO communication equipment (also known as an FSO optomechanical system) in the FSO communication system. Furthermore, the SLM can be applied to the FSO antenna in the FSO communication equipment to enable the FSO antenna to adaptively switch beam types and output, improve anti-turbulence capability, and improve the stability of the communication link.

[0051] The spatial light modulator, driving method, FSO antenna, device, and system provided in the embodiments of this application are described below with reference to the accompanying drawings.

[0052] Figure 1 illustrates an example of an FSO communication system in an embodiment of this application. Referring to Figure 1, the FSO communication system may include an optical transmitting device 100 and an optical receiving device 200. The optical transmitting device 100 can be used to receive electrical signals and process the electrical signals to output optical signals. The optical signals are transmitted through an atmospheric channel. The optical receiving device 200 is used to receive the optical signals and process the optical signals accordingly.

[0053] For example, the optical transmitting device 100 may include an FSO communication device 110, which may include a light source, a signal processing module, and an FSO antenna 111. The FSO antenna 111 is disposed at the rear end of the light source and the signal processing module. The signal processing module receives electrical signals, processes them, and then controls the light source to output relevant optical signals to the FSO antenna 111. The FSO antenna 111 processes the optical signals and transmits them to the atmospheric channel. For example, the optical receiving device 200 may also include the FSO communication device 110, which will not be elaborated here.

[0054] For example, the FSO antenna 111 may include an optical lens and an SLM (Scanning Linear Modulator). The SLM is disposed at the front end of the optical lens and can be used to adjust the amplitude and phase of the optical signal, thereby achieving beam shaping and precise control, compensating for the influence of external factors such as turbulence on the beam, and improving the stability and reliability of communication. The optical signal adjusted by the SLM is input to the optical lens, and after collimation and other processing by the optical lens, it is output to the atmospheric channel.

[0055] Those skilled in the art will understand that the hardware structure of the FSO communication system shown in Figure 1 does not constitute a limitation on the FSO communication system. The FSO communication system provided in the embodiments of this application may include more or fewer components than shown, may combine two or more components, or may have different component configurations. The various components shown in Figure 1 may be implemented in hardware, software, or a combination of hardware and software, including one or more signal processing and / or application-specific integrated circuits.

[0056] In FSO communication, the light beam is easily affected by turbulence during transmission through the atmospheric channel, leading to problems such as light intensity fluctuations and optical power attenuation, causing additional spatial losses, reducing the receiving power at the receiver, and severely hindering its coverage distance. Currently, the types of light beams emitted by the FSO communication device 110 can include Gaussian beams, sharp beams, etc. For example, Figure 2(a) illustrates the light intensity distribution of a Gaussian beam, and Figure 2(b) illustrates the phase distribution of a Gaussian beam. The light intensity distribution of the Gaussian beam, as shown in Figure 2(a), follows a Gaussian function distribution. The phase distribution of the Gaussian beam, as shown in Figure 2(b), follows an equal-phase distribution.

[0057] Sharp beams include, but are not limited to, needle-shaped beams and vortex beams. For example, Figure 2(c) illustrates the intensity distribution of a needle-shaped beam, and Figure 2(d) illustrates the phase distribution of a needle-shaped beam. The intensity distribution of the needle-shaped beam, as shown in Figure 2(c), is angularly uniform and distributed along a specific radial function. The phase distribution of the needle-shaped beam, as shown in Figure 2(d), is angularly uniform. Similarly, Figure 2(e) illustrates the intensity distribution of a vortex beam, and Figure 2(f) illustrates the phase distribution of a vortex beam. The intensity distribution of the vortex beam, as shown in Figure 2(e), is angularly uniform and distributed along a specific radial function. The phase distribution of the vortex beam, as shown in Figure 2(f), is a linearly gradient phase distribution. These are merely examples illustrating some specific beams of sharp beams. In actual implementation, the specific beam of a sharp beam is not limited to the beams provided in the embodiments of this application, but may also be other structures known to those skilled in the art, and are not limited here.

[0058] In practical applications, sharp beams offer superior turbulence resistance compared to Gaussian beams. Furthermore, sharp beams contain a wider variety of beam types. Since the beam types yielding higher gains in sharp beams may differ depending on the turbulence intensity, the FSO antenna 111 needs to have the ability to switch between different beam types to adapt to varying turbulence intensities, thereby maximizing the FSO's turbulence resistance and ensuring the robustness of the communication link. Based on this, this application provides an SLM (Surveyor Lens) that adaptively switches beam types to improve turbulence resistance and enhance the stability of the communication link.

[0059] Figure 3A illustrates a top view of an SLM in an embodiment of this application. Figure 3B illustrates a top view of a second electrode in an embodiment of this application. Figure 3C illustrates a top view of a first electrode in an embodiment of this application. Figure 4A illustrates a cross-sectional view along the AA' direction in Figure 3A. Figure 4B illustrates a cross-sectional view along the BB' direction in Figure 3A. Referring to Figures 3A to 3C, 4A, and 4B, the SLM300 in this embodiment may include: a first substrate 310, a first electrode 330, a liquid crystal layer 350, a second electrode 340, and a second substrate 320 arranged sequentially. The first electrode 330 is a planar electrode, that is, the first electrode 330 is arranged on the entire surface, which can simplify the process fabrication complexity. The second electrode 340 includes a plurality of sub-electrodes 341 to 345 spaced apart from each other. The plurality of sub-electrodes 341 to 345 are arranged sequentially from the inside to the outside around a center. For example, sub-electrode 345 is located on the outermost side, sub-electrode 345 is arranged around sub-electrode 344, sub-electrode 344 is arranged around sub-electrode 343, sub-electrode 343 is arranged around sub-electrode 342, sub-electrode 342 is arranged around sub-electrode 341, and sub-electrode 341 is arranged around the aforementioned center, so that the plurality of sub-electrodes 341 to 345 are arranged in a concentric circle manner. This configuration allows the SLM to be formed as a liquid crystal SLM. When different driving voltages are applied to the first electrode 330 and the sub-electrode respectively, the liquid crystal material in the liquid crystal layer 350 flips under the action of the electric field, resulting in different equivalent dielectric constants. This enables the SLM to adjust the intensity and phase of the incident beam to modulate different types of beams, achieving adaptive switching of beam types. In particular, it can adaptively switch different types of beams in a sharp beam, improving anti-turbulence capability and enhancing the stability of the communication link.

[0060] As an example, the center around which the sub-electrodes 341-345 are located can be an axis extending in a direction perpendicular to the first substrate 310. Exemplarily, this axis passes through the geometric center of the first substrate 310. Alternatively, the axis passes through the geometric center of the second substrate 320. Alternatively, the axis passes through the geometric center of the first electrode 330.

[0061] It is understood that, in order to clearly illustrate the structure of the sub-electrodes in the second electrode 340 in the embodiments of this application, Figures 3A and 3B are illustrated using an example of five sub-electrodes in the second electrode 340. In other embodiments of this application, the second electrode 340 may also have two, five, eight, or more sub-electrodes. Furthermore, in order to increase the phase change of different types of beams along the radial direction in the sharp beam, more sub-electrodes can be set. However, in actual FSO communication, it may not be necessary for the beam to have too much phase change along the radial direction. Therefore, if too many sub-electrodes are set, it may cause performance redundancy and increase costs. Therefore, considering both cost and the beam phase requirements in FSO communication scenarios, in some embodiments of this application, the number of sub-electrodes can be set to 2 to 5 to balance cost and beam phase requirements. Exemplarily, the number of sub-electrodes is 2, 3, 4, or 5, and is not limited here.

[0062] It is understood that the first substrate 310 and the second substrate 320 are not shown in Figure 3A, and their structures can be seen in Figures 4A and 4B.

[0063] As an example, the SLM in this embodiment can be a transmissive SLM to suit transmissive applications, where the light beam emitted from the light source is incident on the SLM, passes through the SLM and is modulated into different types of light beams, especially into different types of beams in a sharp beam. Based on this, the first electrode 330 and each sub-electrode 341-345 can be set as transparent electrodes, and the first substrate 310 and the second substrate 320 can also be set as transparent substrates.

[0064] As another example, the SLM in this embodiment can be a reflective SLM to suit reflective applications, i.e., the beam emitted from the light source is incident on the SLM, and the SLM reflects the beam and modulates it into different types of beams, especially into different types of beams in a sharp beam. Based on this, depending on the arrangement of the SLM in the FSO antenna 111, the first electrode 330 can be set as a reflective electrode, the second substrate 320 as a transparent substrate, and each sub-electrode 341-345 as a transparent electrode; or, each sub-electrode 341-345 can be set as a reflective electrode, the first substrate 310 as a transparent substrate, and the first electrode 330 as a transparent electrode.

[0065] In some embodiments of this application, referring to Figures 3A and 3B, the plurality of sub-electrodes 341-345 can be configured as non-closed annular electrodes, that is, the plurality of sub-electrodes 341-345 form a non-closed pattern, thereby accommodating the needs of different types of beams in a sharp beam, such as needle-shaped beams, vortex beams, and bottle-shaped beams in a sharp beam. Exemplarily, a non-closed annular electrode refers to an electrode that is annular but forms a non-closed pattern. For example, an opening GK is formed between the two ends of the plurality of sub-electrodes 341-345, which are not in contact with each other, forming an unclosed pattern. Exemplarily, referring to Figures 3A and 3B, the openings GK of the plurality of sub-electrodes 341-345 face the same direction, which makes the implementation of the sub-electrodes 341-345 relatively simple, thereby reducing design difficulty and production costs. Alternatively, referring to Figure 5, which exemplarily illustrates another top view of the second electrode in an embodiment of this application, the openings GK of the plurality of sub-electrodes 341-345 are arranged in a sequentially rotated manner from the inside out. This also simplifies the implementation of the sub-electrodes 341-345, thereby reducing design difficulty and production costs. The above are merely examples illustrating some specific forms of the opening orientation of the sub-electrodes in embodiments of this application. In specific implementations, the opening orientation of the sub-electrodes is not limited to the methods provided in the embodiments of this application, and may also be other forms known to those skilled in the art, which are not limited here.

[0066] In some embodiments of this application, at least some sub-electrodes can have the same width, reducing design complexity and production costs. For example, referring to FIG3B, each sub-electrode 341-345 can have the same width; for instance, the widths W1 of sub-electrode 341, W2 of sub-electrode 342, W3 of sub-electrode 343, W4 of sub-electrode 344, and W5 of sub-electrode 345 can be the same, allowing for uniform arrangement of each sub-electrode and improving the uniformity and stability of the modulated beam intensity. In other embodiments of this application, some sub-electrodes may have different widths, some may have the same width, or all sub-electrodes may have different widths.

[0067] In some embodiments of this application, the multiple sub-electrodes 341-345 can be equally spaced, which can uniformly distribute the sub-electrodes, optimize the layout, further reduce design difficulty, and lower production costs. For example, referring to Figure 3B, the spacing D1 between sub-electrodes 341 and 342, the spacing D2 between sub-electrodes 342 and 343, the spacing D3 between sub-electrodes 343 and 344, and the spacing D4 between sub-electrodes 344 and 345 are the same, which can uniformly distribute each sub-electrode, improving the uniformity and stability of the modulated beam intensity. In other embodiments of this application, the spacing between some sub-electrodes may be different, the spacing between some sub-electrodes may be the same, or the spacing between each adjacent sub-electrode may be different.

[0068] For example, referring to Figures 3A, 3B, and 5, the SLM can be a square SLM, with the sub-electrodes 341-345 in square shape. Alternatively, referring to Figure 6A, which exemplarily illustrates another top view of the SLM in an embodiment of this application, the SLM 300 can be a rectangular SLM, with the sub-electrodes 341-345 in rectangular shape. Alternatively, referring to Figure 6B, which exemplarily illustrates another top view of the SLM in an embodiment of this application, the SLM 300 can be a circular SLM, with the sub-electrodes 341-345 in circular shape. Or, referring to Figure 6C, which exemplarily illustrates another top view of the SLM in an embodiment of this application, the SLM 300 can be an elliptical SLM, with the sub-electrodes 341-345 in elliptical shape. This configuration allows the shape of the sub-electrodes 341-345 to follow the shape of the SLM, thus making it suitable for beams of different types and angles of incidence. It is understood that square and circular SLMs are suitable for transmission-type applications, meaning the shape of a transmission-type SLM can be square or circular. Furthermore, the specific shape of a transmission-type SLM can be flexibly designed according to the actual application scenario and is not limited here. Similarly, rectangular and elliptical SLMs are suitable for reflection-type applications, meaning the shape of a reflection-type SLM can be rectangular or elliptical. The specific shape of a reflection-type SLM can be flexibly designed according to the actual application scenario and is not limited here. The above are merely examples illustrating some specific shapes of the SLM and sub-electrodes in the embodiments of this application. In specific implementations, the specific shapes of the SLM and sub-electrodes are not limited to the beams provided in the embodiments of this application, and can also be other shapes known to those skilled in the art, and are not limited here. It is understood that when sub-electrodes 341-345 are non-closed ring electrodes, the outline of the shape of sub-electrodes 341-345 can be approximately square, rectangular, circular, or elliptical, all of which fall within the protection scope of this application. In addition, the above shapes can be combined according to the needs of the actual application scenario to meet the requirements.

[0069] In some embodiments of this application, the SLM further includes a driving circuit, which is connected to the plurality of sub-electrodes 341-345 respectively. The driving circuit outputs different driving voltages to each sub-electrode, so that each sub-electrode has an electric field of different intensity with respect to the first electrode 330. This allows the SLM to adjust the intensity and phase of the incident light beam to modulate different types of light beams, especially different types of beams within a sharp beam. Exemplarily, the driving circuit can be a voltage control chip, and the driving pins of the voltage control chip can be connected to each sub-electrode via signal traces to transmit the driving voltage. Exemplarily, the signal traces can be disposed between the layer containing the second electrode 340 and the second substrate 320, and an insulating layer exists between the layer containing the signal traces and the layer containing the second electrode 340. The signal traces are connected to the sub-electrodes through contact holes penetrating the insulating layer.

[0070] For example, taking the SLM structure shown in Figures 3A and 3B as an example, the driving circuit is connected to both ends of each sub-electrode respectively. The driving circuit is used to output driving voltages to both ends of the same sub-electrode respectively, so that the beam modulated by the SLM meets the requirements of the application scenario. In some embodiments, the type of modulated beam can be adaptively switched by adjusting the magnitude of the driving voltage.

[0071] As an example, taking the SLM structure shown in Figures 3A and 3B, the driving circuit outputs the same driving voltage to both ends of the same sub-electrode, and the first electrode 330 is also loaded with a reference voltage to modulate the needle-shaped beam shown in Figures 2(c) and (d). Exemplarily, referring to Figure 7, which illustrates a schematic diagram of the second electrode 340 loaded with a driving voltage in an embodiment of this application, the first electrode 330 is loaded with a reference voltage, and the driving circuit outputs the same driving voltages V1a and V1b to both ends of the sub-electrode 341, making the potentials on the sub-electrode 341 the same. The driving circuit outputs the same driving voltages V2a and V2b to both ends of the sub-electrode 342, making the potentials on the sub-electrode 342 the same. The driving circuit outputs the same driving voltages V3a and V3b to both ends of the sub-electrode 343, making the potentials on the sub-electrode 343 the same. The driving circuit outputs the same driving voltages V4a and V4b to both ends of the sub-electrode 344, making the potentials on the sub-electrode 344 the same. The driving circuit outputs the same driving voltages V5a and V5b to both ends of the sub-electrode 345, making the potentials on the sub-electrode 345 the same. Furthermore, V1a, V2a, V3a, V4a, and V5a are all different, thereby enabling the modulation of a beam with a phase uniformly distributed along the angular direction, and thus making the beam modulated by the SLM into a needle-shaped beam as shown in Figures 2(c) and (d).

[0072] As another example, taking the SLM structure shown in Figures 3A and 3B as an example, the driving circuit is used to output different driving voltages to the two ends of the same sub-electrode, and a reference voltage is also applied to the first electrode 330 to modulate the needle-shaped beam shown in Figures 2(e) and (f). Exemplarily, referring to Figure 7, the driving voltages V1a and V1b are different, causing the potential on sub-electrode 341 to gradually change from V1a to V1b. The driving voltages V2a and V2b are different, causing the potential on sub-electrode 342 to gradually change from V2a to V2b. The driving voltages V3a and V3b are different, causing the potential on sub-electrode 343 to gradually change from V3a to V3b. The driving voltages V4a and V4b are different, causing the potential on sub-electrode 344 to gradually change from V4a to V4b. The driving voltages V5a and V5b are different, causing the potential on sub-electrode 345 to gradually change from V5a to V5b. Furthermore, V1a, V2a, V3a, V4a, and V5a are all different, as are V1b, V2b, V3b, V4b, and V5b. This allows for the modulation of a beam with a phase that exhibits a linear gradient along the angular direction, resulting in a needle-shaped beam as shown in Figures 2(e) and (f). It is understood that the driving voltages V1a, V2a, V3a, V4a, V5a, and V1b, V2b, V3b, V4b, V5b can fall within the voltage range [Vmin, Vmax]. By selecting two different voltage values ​​within this range and applying them to the same sub-electrode, a phase-gradient beam can be modulated through this sub-electrode. Vmin and Vmax are related to the thickness of the liquid crystal layer, and their values ​​can be flexibly designed according to the requirements of the actual application scenario; no limitations are imposed here.

[0073] As another example, taking the SLM structure shown in Figures 3A and 3B as an example, the driving circuit is used to output the same driving voltage to both ends of each sub-electrode, and a reference voltage is applied to the first electrode 330 to modulate the Gaussian beam shown in Figures 2(a) and (b). Exemplarily, referring to Figure 7, the driving voltages V1a, V1b, V2a, V2b, V3a, V3b, V4a, V4b, V5a, and V5b are all the same, thereby enabling the modulation of a beam with equal phase distribution, so that the beam modulated by the SLM can be the Gaussian beam shown in Figures 2(a) and (b).

[0074] For example, the reference voltage can be the ground voltage, in which case the first electrode 330 can be directly grounded. Alternatively, the reference voltage can be other voltage values, which are not limited in this application.

[0075] Compared to existing SLMs, the SLM in this application embodiment reduces the number of driving circuits used. For example, referring to FIG8, which exemplarily illustrates a schematic diagram of the second electrode 340 in an existing SLM, taking a square SLM as an example, the second electrode 340 of this SLM has N×N pixel electrodes 10, which are block electrodes arranged in an array. To form a Gaussian beam and a sharp beam, a driving voltage needs to be input to each pixel electrode 10, thus requiring a total of N×N driving voltages. Taking a voltage control chip as an example, assuming the number of driving pins of the voltage control chip is M, the number of voltage control chips required to output a driving voltage to each pixel electrode 10 is ceil(N). 2 / M), ceil represents rounding up. For example, referring to Figure 9(a), which exemplarily illustrates a light intensity diagram of a beam modulated by a prior art SLM, taking N=100 as an example, outputting driving voltages to 100×100 pixel electrodes 10 respectively, although the prior art SLM can modulate a beam of light intensity with angular uniformity and radial special function distribution as shown in Figure 9(a). If the voltage control chip has a total of 1024 driving pins, then the prior art SLM requires a total of 10 voltage control chips. If the voltage control chip has fewer driving pins, then the prior art SLM will require more voltage control chips, resulting in a more complex structure of the voltage control chips and an increase in the size and cost of the SLM.

[0076] Taking the square SLM shown in Figure 3A of this application as an example, assuming that the size of this SLM is the same as that of the square SLM in the prior art, and that the second electrode 340 in this SLM has K sub-electrodes, the area where each sub-electrode is located can correspond to the area where multiple pixel electrodes 10 are located, it can optimize the layout of the second electrode 340 and simplify the process fabrication complexity. To form a Gaussian beam and a sharp beam, a driving voltage needs to be input to each sub-electrode, so a total of 2K driving voltages are required, and the number of voltage control chips required is ceil (2K / M). Since the area where each sub-electrode is located can correspond to the area where multiple pixel electrodes 10 are located, 2K is much smaller than N. 2 This reduces the number of voltage control chips, thereby reducing the size and cost of the SLM.

[0077] As an example, referring to Figure 9(b), which exemplarily illustrates a light intensity diagram of a beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of 10 pixel electrodes 10, taking N=100 as an example, then K=5, such that the sub-electrode, as shown in Figures 3A and 3B, enables the SLM to modulate a beam with angular uniformity and a light intensity distributed along a specific radial function, as shown in Figure 9(b). Furthermore, in this embodiment, a total of 10 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 10 driving pins can be used, thereby simplifying the complexity of the control circuit and reducing the size and cost of the SLM.

[0078] As another example, referring to Figure 9(c), which exemplarily illustrates another light intensity diagram of the beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of five pixel electrodes 10, taking N=100 as an example, then K=20, which allows the SLM to modulate a beam with angular uniformity and a light intensity distributed along a specific radial function, as shown in Figure 9(c). Furthermore, in this embodiment, a total of 40 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 40 driving pins can be used, thereby simplifying the complexity of the control circuit and reducing the size and cost of the SLM.

[0079] As another example, referring to Figure 9(d), which exemplarily illustrates another light intensity diagram of the beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of two pixel electrodes 10, taking N=100 as an example, then K=50, which allows the SLM to modulate a beam with angular uniformity and a light intensity distributed along a specific radial function, as shown in Figure 9(d). Furthermore, in this embodiment, a total of 100 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 100 driving pins can be used, thereby simplifying the complexity of the control circuit and reducing the size and cost of the SLM.

[0080] As another example, referring to Figure 9(e), which exemplarily illustrates another light intensity diagram of the beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of one pixel electrode 10, taking N=100 as an example, then K=100, which allows the SLM to modulate a beam with angular uniformity and a light intensity distributed along a specific radial function, as shown in Figure 9(e). Furthermore, in this embodiment, a total of 200 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 200 driving pins can be used, thereby simplifying the complexity of the control circuit and reducing the size and cost of the SLM.

[0081] Furthermore, the path loss and probability relationships of the five beams shown in Figures 9(a) to (e) under 500 strong turbulence conditions were simulated. The simulation results are shown in Figure 10, where the horizontal axis represents path loss and the vertical axis represents probability. L1 represents the path loss and probability relationship curve of the five beams shown in Figure 9(a) under 500 strong turbulence conditions, L2 represents the path loss and probability relationship curve of the five beams shown in Figure 9(b) under 500 strong turbulence conditions, and L3 represents the path loss and probability relationship curve of the five beams shown in Figure 9(c) under 500 strong turbulence conditions. The curves showing the path loss and probability relationship of the five beams under 500 strong turbulence conditions are illustrated in Figure 9(d). L4 represents the path loss and probability relationship curve of the five beams shown in Figure 9(e) under 500 strong turbulence conditions. Referring to the simulation results shown in Figure 10, these five curves L1 to L5 almost overlap, indicating that the anti-turbulence effect of the five beams shown in Figure 9(a) to (e) is consistent. Therefore, the SLM in this embodiment not only simplifies the complexity, size, and cost of the control circuit, but also enables the modulated beam to have superior anti-turbulence capability, supporting FSO anti-turbulence robust transmission.

[0082] Figure 11A illustrates another top view of the SLM in this embodiment, and Figure 11B illustrates another top view of the second electrode in this embodiment. Referring to Figures 11A and 11B, this embodiment modifies the implementation method in the above embodiments. The similarities are not repeated here. The difference is that the plurality of sub-electrodes 341 to 345 can also be set as closed ring electrodes, that is, the plurality of sub-electrodes 341 to 345 form a closed pattern, so as to take into account the needs of different types of beams in the sharp beam, especially the needs of needle beams and bottle beams.

[0083] In other embodiments of this application, the plurality of sub-electrodes 341-345 may also include a combination of non-closed ring electrodes and closed ring electrodes.

[0084] For example, taking the SLM structure shown in Figures 11A and 11B as an example, the driving circuit is connected to each sub-electrode respectively. The driving circuit is used to output the same or different driving voltages to each sub-electrode. In addition, the first electrode 330 is also loaded with a reference voltage so that the beam modulated by the SLM meets the requirements of the application scenario. As an example, referring to Figure 12, Figure 12 illustrates a schematic diagram of the second electrode being loaded with a driving voltage in an embodiment of this application. The driving circuit outputs a driving voltage V1c to sub-electrode 341, a driving voltage V2c to sub-electrode 342, a driving voltage V3c to sub-electrode 343, a driving voltage V4c to sub-electrode 344, and a driving voltage V5c to sub-electrode 345. Among them, V1c, V2c, V3c, V4c, and V5c are all different, so that a beam with a phase uniformly distributed along the angular direction can be modulated, thereby making the beam modulated by the SLM into a needle-shaped beam as shown in Figures 2(c) and (d). Alternatively, V1c, V2c, V3c, V4c, and V5c can all be the same, thus enabling the modulation of beams with equal phase distribution, which in turn allows the beam modulated by the SLM to be a Gaussian beam as shown in Figure 2(a) and (b).

[0085] Compared to existing SLMs, the SLM in this application embodiment reduces the number of driving circuits used. Taking the square SLM shown in Figure 11A of this application as an example, assuming that the size of this SLM is the same as that of a square SLM in the prior art, and that the second electrode 340 in this SLM has K sub-electrodes, the area of ​​each sub-electrode can correspond to the area of ​​multiple pixel electrodes 10, it can optimize the layout of the second electrode 340 and simplify the process fabrication complexity. To form a Gaussian beam and a sharp beam, a driving voltage needs to be input to each sub-electrode, so a total of K driving voltages are required, and the number of voltage control chips required is ceil(K / M). Since the area of ​​each sub-electrode can correspond to the area of ​​multiple pixel electrodes 10, K is much smaller than N. 2 This allows for a further reduction in the number of voltage control chips, and further reduces the size and cost of the SLM.

[0086] As an example, referring to Figure 13(a), which exemplarily illustrates a light intensity diagram of a beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of 10 pixel electrodes 10, taking N=100 as an example, then K=5, such that the sub-electrodes, as shown in Figures 11A and 11B, enable the SLM to modulate a beam with angular uniformity and a radially specific function-distributed light intensity, as shown in Figure 13(a). Furthermore, in this embodiment, a total of 5 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only further reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 5 driving pins can be used, thereby further simplifying the complexity of the control circuit and further reducing the size and cost of the SLM.

[0087] As another example, referring to Figure 13(b), which exemplarily illustrates another light intensity diagram of the beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of five pixel electrodes 10, taking N=100 as an example, then K=20, enabling the SLM to modulate a beam with angularly uniform intensity and a radially specific function distribution, as shown in Figure 13(b). Furthermore, in this embodiment, a total of 20 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only further reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 20 driving pins can be used, thereby further simplifying the complexity of the control circuit and further reducing the size and cost of the SLM.

[0088] As another example, referring to Figure 13(c), which exemplarily illustrates another light intensity diagram of the beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of two pixel electrodes 10, taking N=100 as an example, then K=50, which allows the SLM to modulate a beam with angular uniformity and a light intensity distributed along a specific radial function, as shown in Figure 13(c). Furthermore, in this embodiment, a total of 50 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only further reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 50 driving pins can be used, thereby further simplifying the complexity of the control circuit and further reducing the size and cost of the SLM.

[0089] As another example, referring to Figure 13(d), which exemplarily illustrates another light intensity diagram of the beam modulated by the SLM in this embodiment, assuming the width of any sub-electrode is the sum of the widths of one pixel electrode 10, taking N=100 as an example, then K=100, which allows the SLM to modulate a beam with angular uniformity and a light intensity distributed along a specific radial function, as shown in Figure 13(d). Furthermore, in this embodiment, a total of 100 driving voltages are required, making the number of driving voltages far less than the 10,000 in the prior art. This not only further reduces the number of voltage control chips but also allows for the use of voltage control chips with fewer driving pins in the SLM. For example, a voltage control chip with 100 driving pins can be used, thereby further simplifying the complexity of the control circuit and further reducing the size and cost of the SLM.

[0090] Furthermore, the path loss and probability relationships of the five beams shown in Figures 13(a) to (d) under 500 strong turbulence conditions were simulated. The simulation results are shown in Figure 14. L1 represents the path loss and probability relationship curve of the five beams shown in Figure 9(a) under 500 strong turbulence conditions, L2 represents the path loss and probability relationship curve of the five beams shown in Figure 13(a) under 500 strong turbulence conditions, and L3 represents the path loss and probability relationship curve of the five beams shown in Figure 13(b) under 500 strong turbulence conditions. The path loss and probability curves under turbulent conditions are shown in Figure 13(c). L4 represents the path loss and probability curves of the five beams shown in Figure 13(d) under 500 strong turbulent conditions. Referring to the simulation results shown in Figure 14, these five curves L1 to L5 almost overlap, indicating that the anti-turbulence effects of the five beams shown in Figures 13(a) to (d) and Figure 9(a) are consistent. Therefore, the SLM in this embodiment not only simplifies the complexity, size, and cost of the control circuit, but also enables the modulated beam to have superior anti-turbulence capability, supporting FSO anti-turbulence robust transmission.

[0091] Based on the same inventive concept and according to the content described in the above embodiments, this application also provides an SLM driving method, which will be described in detail below.

[0092] For example, the method includes: applying different driving voltages to each sub-electrode and applying a reference voltage to the first electrode.

[0093] For example, the sub-electrode is a non-closed ring electrode. Applying a driving voltage to the sub-electrode includes applying the same driving voltage or different driving voltages to both ends of the same sub-electrode. In some embodiments of this application, the descriptions related to Figures 3A to 10 above can be regarded as implementations of the method shown in this embodiment, and will not be elaborated here.

[0094] For example, the sub-electrode is a closed loop electrode, and applying a driving voltage to the sub-electrode includes applying a different driving voltage to each sub-electrode. In some embodiments of this application, the descriptions related to Figures 11A to 14 above can be regarded as implementations of the method shown in this embodiment, and will not be elaborated here.

[0095] The above description is only a specific implementation of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application.

Claims

1. A spatial light modulator, characterized in that, include: A first substrate, a first electrode, a liquid crystal layer, a second electrode, and a second substrate are sequentially arranged. The first electrode is a planar electrode; The second electrode includes a plurality of sub-electrodes spaced apart from each other, the plurality of sub-electrodes being arranged sequentially from the inside out around a center.

2. The spatial light modulator according to claim 1, characterized in that, The plurality of sub-electrodes include one or a combination of non-closed ring electrodes and closed ring electrodes.

3. The spatial light modulator according to claim 2, characterized in that, The plurality of sub-electrodes are all non-closed ring electrodes, and an opening is formed between the two ends of each sub-electrode; The openings of the plurality of sub-electrodes face the same direction, or the openings of the plurality of sub-electrodes are arranged in a rotating manner from the inside to the outside.

4. The spatial light modulator according to any one of claims 1-3, characterized in that, At least some of the sub-electrodes have the same width.

5. The spatial light modulator according to any one of claims 1-4, characterized in that, The multiple sub-electrodes are arranged at equal intervals.

6. The spatial light modulator according to any one of claims 1-5, characterized in that, The shape of the sub-electrode includes one or a combination of square, rectangle, circle and ellipse.

7. The spatial light modulator according to any one of claims 1-6, characterized in that, It also includes a driving circuit, which is connected to the plurality of sub-electrodes respectively; The driving circuit is used to output different driving voltages to each of the sub-electrodes.

8. The spatial light modulator according to claim 7, characterized in that, The sub-electrode is a non-closed ring electrode, and the driving circuit is connected to both ends of each sub-electrode respectively; The driving circuit is used to output the same driving voltage or different driving voltages to both ends of the same sub-electrode.

9. A driving method for a spatial light modulator, characterized in that, The spatial light modulator includes a first substrate, a first electrode, a liquid crystal layer, a second electrode, and a second substrate arranged sequentially. The first electrode is a planar electrode, and the second electrode includes a plurality of sub-electrodes arranged at intervals around each other. The plurality of sub-electrodes are arranged at intervals from the inside to the outside around a center. The method includes: Different driving voltages are applied to each of the sub-electrodes, and a reference voltage is applied to the first electrode.

10. The method according to claim 9, characterized in that, The sub-electrode is a non-closed ring electrode, and the driving circuit is connected to both ends of the same sub-electrode respectively; Applying a driving voltage to the sub-electrode includes: The same driving voltage or different driving voltages are applied to both ends of the same sub-electrode.

11. A free-space optical antenna, characterized in that, It includes an optical lens and a spatial light modulator as described in any one of claims 1-8, wherein the spatial light modulator is disposed at the front end of the optical lens.

12. A free-space optical communication device, characterized in that, It includes a light source, a signal processing module, and a free-space optical antenna as described in claim 11, wherein the free-space optical antenna is disposed at the rear end of the light source and the signal processing module.

13. A free-space optical communication system, characterized in that, include: An optical transmitting device and an optical receiving device, wherein the optical transmitting device or optical receiving device includes the free-space optical communication device as described in claim 12.

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