A liquid crystal device, optical modulation apparatus and system

Abstract

Embodiments of the present application provide a liquid crystal device, an optical modulation device and a system, which are applied in the fields of wavelength selective switch, laser radar, unmanned driving, laser display and the like. The liquid crystal device comprises a silicon-based backplane, a liquid crystal layer, a transparent cover plate, a super-structured surface structure and a cladding layer. The liquid crystal layer is located between the transparent cover plate and the cladding layer, the cladding layer is located between the super-structured surface structure and the liquid crystal layer, and the super-structured surface structure is located between the cladding layer and the silicon-based backplane. The device disclosed in the present application produces a pre-tilt angle by preparing a super-structured surface structure, and combines the modulation range of the liquid crystal layer of a traditional LCoS device to improve the overall beam angle scanning range, that is, to realize large-angle deflection of the liquid crystal device (for example, LCoS) while maintaining low insertion loss.

Description

Technical Field

[0001] This application relates to the field of optical communication, and more specifically, to a liquid crystal device, an optical modulation apparatus, and a system. Background Technology

[0002] Beam deflection technology is a technique for precisely controlling the propagation direction of a light beam. Optical phased array technology holds a unique advantage among various beam deflection technologies due to its characteristics such as miniaturization, simultaneous multi-channel control, and electronic programmable control. It is achieved by modulating the wavefront phase, causing the beam to deflect in a specific direction to achieve beam scanning.

[0003] Among them, liquid crystal on silicon (LCoS), as a liquid crystal optical phased array device, can produce an effect equivalent to a grating after incident light transmission, realizing high-resolution spatial light phase modulation, thereby changing the propagation direction of the beam. Although liquid crystal optical phased array devices can achieve high-precision, non-mechanical, and stable beam scanning within a certain range, their deflection angle is limited due to the large pixel size and optical return region, and they are prone to high insertion loss under large-angle deflection.

[0004] Therefore, how to achieve large-angle deflection of LCoS devices while maintaining low insertion loss is an urgent problem to be solved. Summary of the Invention

[0005] This application provides a liquid crystal device, an optical modulation apparatus, and a system that can achieve large-angle deflection of incident light while maintaining low insertion loss of the device.

[0006] In a first aspect, a liquid crystal device is provided, comprising: a silicon-based backplane, a liquid crystal layer, a transparent cover plate, a metasurface structure, and a coating layer. The liquid crystal layer is located between the transparent cover plate and the coating layer, the coating layer is located between the metasurface structure and the liquid crystal layer, and the metasurface structure is located between the coating layer and the silicon-based backplane.

[0007] The materials of the metasurface structure and the coating layer are different. For example, the material of the metasurface structure can be silicon, and the material of the coating layer can be silicon oxide or silicon nitride.

[0008] It should be noted that, in the embodiments of this application, the metasurface structure can also be referred to as a metasurface structure. It should be understood that a metasurface structure is an ultrathin micro / nano optical structure on the order of lateral subwavelength size with beam deflection function, used to achieve efficient light focusing and beam shaping. It can achieve accurate control of the full 2π phase on a thin film structure layer of less than one optical wavelength, thereby enabling flexible and effective control of the phase, polarization mode, and propagation mode of light and electromagnetic waves.

[0009] Specifically, metasurface structures are used to adjust the deflection angle of optical signals. The specific beam deflection angle can be flexibly adjusted by designing different micro / nano structures, such as changing the size, material, and spatial arrangement of the micro / nano structures on a silicon-based backplane, ultimately achieving beam deflection scanning over a wide angle range. The cladding layer is used to flatten the metasurface structure. Flattening refers to leveling the surface of the micro / nano structure (metasurface structure), making it smooth and facilitating compatibility with subsequent liquid crystal layer encapsulation processes.

[0010] The liquid crystal device disclosed in this application, taking a traditional LCoS device as an example, introduces a beam pretilt angle (A) by fabricating one or more metasurface structures between a silicon-based backplane and a liquid crystal layer to achieve pretilt of the beam propagation direction. Compared with traditional liquid crystal devices, it provides an additional degree of freedom in adjusting the beam deflection angle, allowing for flexible adjustment of the device's beam scanning range by changing the degree of the pretilt angle. By utilizing the static deflection of the beam by the metasurface structure and the dynamic deflection scanning (-B to B) of the beam by the liquid crystal layer in a traditional LCoS device, the overall beam angle scanning range (AB to A+B) is improved.

[0011] Furthermore, the large-angle beam scanning function of the liquid crystal device disclosed in this application is derived from the introduction of metasurface structure, which does not rely on the modulation of the liquid crystal layer of the device. Its diffraction efficiency and insertion loss are no different from those of traditional devices, and it can significantly increase the scanning angle range of the device while maintaining low insertion loss.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the liquid crystal device is a silicon-based liquid crystal (LCoS) device.

[0013] Optionally, the liquid crystal device is a liquid crystal display (LCD). An LCD is constructed by placing a liquid crystal cell between two parallel glass substrates. A thin-film transistor (TFT) is disposed on the lower glass substrate, and a color filter is disposed on the upper glass substrate. By changing the signals and voltages on the TFTs, the rotation direction of the liquid crystal molecules is controlled, thereby controlling whether polarized light is emitted from each pixel to achieve the display purpose.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, the side of the transparent cover plate closest to the liquid crystal layer includes an electrode layer #1.

[0015] Electrode layer #1 is used to protect the liquid crystal layer and to allow light signals to pass through and conduct electricity.

[0016] Optionally, an electrode layer #2 is included between the liquid crystal layer and the coating layer. That is, the liquid crystal layer includes a guiding material that can fix the alignment direction of the liquid crystal molecules under zero voltage. Therefore, electrode layers are present on both the top and bottom sides of the liquid crystal layer. For example, electrode layer #1 is the negative electrode, and electrode layer #2 is the positive electrode.

[0017] In conjunction with the first aspect, in some implementations of the first aspect, electrode layer #1 is an indium tin oxide (ITO) layer.

[0018] The ITO layer has excellent conductivity and transparency, allowing light signals to pass through and conduct electricity.

[0019] In conjunction with the first aspect, in some implementations of the first aspect, the silicon-based backplane includes a driving circuit, a reflective layer, and a passivation layer, the reflective layer and the passivation layer being located between the metasurface structure and the driving circuit.

[0020] For example, the reflective layer can be made of aluminum (Al) to improve the reflectivity of the silicon-based backplane. The passivation layer can be made of dielectric materials such as SiO2 or SiN to prevent Al metal oxidation.

[0021] For example, the driving circuit can be a CMOS chip used to apply a voltage between the reflective layer and the transparent cover to drive the modulation liquid crystal layer (e.g., the rotation angle of the liquid crystal molecules) to achieve phase modulation of the light beam.

[0022] Optionally, the silicon-based backplane further includes an electrode layer #2 and a pixel array. The driving circuit, electrode layer #2, pixel array, reflective layer, and passivation layer can be integrated on the silicon-based backplane; or, the electrode layer #2 and pixel array are integrated on the driving circuit, and the driving circuit, reflective layer, and passivation layer are integrated on the silicon-based backplane.

[0023] In conjunction with the first aspect, in some implementations of the first aspect, the metasurface structure comprises multiple cells, each of which comprises multiple micro / nano structures, and the surface area of ​​the multiple micro / nano structures gradually increases along the same direction.

[0024] It should be understood that micro- and nanostructures are ultrathin structures with subwavelength scale. Each micro- and nanostructure has a specific phase delay for incident light, and the size and spatial arrangement of different micro- and nanostructures can generate specific phase gradients.

[0025] The fact that the surface area of ​​multiple micro- and nanostructures gradually increases along the same direction can be understood as the geometric parameters (e.g., radius R, side length (e.g., length and width), perimeter) of multiple micro- and nanostructures gradually increasing along the same direction.

[0026] For example, when the shape of the micro / nano structure is rectangular, the corresponding geometric parameters can be length, width, or perimeter; when the shape of the micro / nano structure is cylindrical, the corresponding geometric parameters can be R or perimeter.

[0027] In this implementation, the metasurface structure is generally arranged periodically according to cells. That is, the periods of multiple cells of the same metasurface structure are usually the same, and the geometric parameters of multiple micro- and nanostructures within each cell gradually change along the same direction. For example, if metasurface structure #1 includes cells #1 and #2, then cells #1 and #2 each include 6 micro- and nanostructures, and the surface area of ​​these 6 micro- and nanostructures increases sequentially within the cell along the same direction (e.g., from left to right).

[0028] In conjunction with the first aspect, in some implementations of the first aspect, the liquid crystal device includes multiple metasurface structures, wherein any two metasurface structures are located in different regions of a silicon-based backplane, and the cell periods of any two metasurface structures are different.

[0029] Specifically, according to the blazed grating formula tanθ=λ / T, the beam deflection angle θ is inversely proportional to the grating period T. Here, λ represents the incident light wavelength.

[0030] The beam deflection angle θ can be flexibly adjusted by changing the phase gradient. Different phase gradients (e.g., 0 to 2π) can be generated by utilizing the different periods of the cells of the metasurface structure, thereby introducing different pretilt angles (A) to achieve beam deflection in the range of -90° to 90°.

[0031] For example, metasurface structure #1 includes cell #1 and cell #2, each comprising 10 micro / nano structures with sizes gradually increasing from 1 nm to 10 nm and a phase gradient of 0–2π. Similarly, metasurface structure #2 includes cell #3 and cell #4, each comprising 8 micro / nano structures with sizes gradually increasing from 1 nm to 8 nm and a phase gradient of 0–π. In this case, the cell periods of metasurface structure #1 (cell #1) and metasurface structure #2 (cell #3) are different.

[0032] In conjunction with the first aspect, in some implementations of the first aspect, the number of micro- and nano-structures within the cells of any two metasurface structures is different.

[0033] For example, the cell of metasurface structure #1 includes 10 micro / nano structures, and the cell of metasurface structure #2 includes 8 micro / nano structures.

[0034] Based on the above scheme, the pretilt angle A can be adjusted by changing the number of micro-nano structures, thereby generating different phase gradients to achieve beam deflection in different ranges, such as -90 to 90°.

[0035] In conjunction with the first aspect, in some implementations of the first aspect, the sizes of the micro-nano structures within the cells of any two metasurface structures are different, and the sizes of the micro-nano structures are related to the wavelength of the incident light.

[0036] It should be understood that the size of micro / nano structures is related to the wavelength of incident light. It can be understood that the size of micro / nano structures generally varies from λ / 4 to λ / 2, where λ is the wavelength of incident light. That is, the size of micro / nano structures is greater than or equal to one-quarter of the wavelength of incident light and less than or equal to one-half of the wavelength of incident light.

[0037] For example, if the wavelength of the incident light is 400 nm, the size range of the micro / nano structure can be from 100 nm to 200 nm.

[0038] Based on the above scheme, the pretilt angle A can be adjusted by changing the size of the micro / nano structure, thereby generating different phase gradients to achieve beam deflection in different ranges, such as -90 to 90°.

[0039] In conjunction with the first aspect, in some implementations of the first aspect, the liquid crystal device further includes a reflective device. The reflective device is used to direct the incident light, after the first-stage optical modulation, onto a second region of the liquid crystal device for second-stage optical modulation. The first-stage optical modulation is based on the incident light illuminating a first region of the liquid crystal device, and the second region is located in a different region from the first region on a silicon-based backplane.

[0040] For example, the reflective device may be a lens, and one side of the lens has a reflective coating with a central cutout.

[0041] Based on the above scheme, by irradiating two different regions of the silicon-based backplane of the liquid crystal device with incident light twice and performing two-stage optical modulation, the overall beam deflection capability of the liquid crystal device can be expanded. For example, the angle range of the first-stage optical modulation is -B to B, and the angle range of the second-stage optical modulation is AB to A+B, where A is the pretilt angle introduced by the metasurface structure.

[0042] In conjunction with the first aspect, in some implementations of the first aspect, the shape of the micro / nanostructure includes at least one of rectangular, cylindrical, or elliptical cylindrical shapes.

[0043] In other words, the shapes of micro- and nanostructures within the same cell, or within cells of different metasurface structures, can be the same or different, and this application does not impose specific limitations on this. However, from the perspective of CMOS process design, the shapes of multiple micro- and nanostructures within the same cell are usually the same.

[0044] In conjunction with the first aspect, in some implementations of the first aspect, the material of the micro / nano structure includes at least one of gold, silver, aluminum, silicon, gallium nitride, or titanium oxide.

[0045] In other words, the materials of micro- and nanostructures within the same cell, or within cells of different metasurface structures, can be the same or different; this application does not impose specific limitations on this. However, from a CMOS process design perspective, the materials of multiple micro- and nanostructures within the same cell are usually the same.

[0046] In a second aspect, an optical modulation apparatus is provided, comprising: a reflective device, and a liquid crystal device as described in the first aspect or any possible implementation thereof. The reflective device is used to irradiate a second region of the liquid crystal device with incident light that has undergone first-level optical modulation, to perform second-level optical modulation, wherein the first-level optical modulation is based on the incident light irradiating a first region of the liquid crystal device.

[0047] The metasurface structure in the second region is different from that in the first region; that is, any two metasurface structures are located in different regions on the silicon-based backplane.

[0048] It should be understood that the first region and the second region can be viewed as different regions on a silicon-based backplane, for example, see [link to relevant documentation]. Figure 4 The schematic diagram of the partitioned structure of the silicon-based backplane shown shows that the metasurface structures in the first and second regions are different. This can be understood as the differences in the size, material, shape, etc. of the micro-nano structures in the cells of the metasurface structures in the two regions, as well as the different periods of the cells of the metasurface structures.

[0049] That is, a subwavelength metasurface structure with beam deflection function is integrated onto a silicon-based backplane to achieve pre-tilt of the beam propagation direction. The specific beam deflection angle A (or pre-tilt angle A) can be flexibly adjusted by different designed micro / nano structures (e.g., by changing the size, material, and spatial arrangement of the micro / nano structures), ultimately achieving beam deflection scanning over a large angle range.

[0050] Optionally, the reflective device is a lens, and one side of the lens has a centrally hollowed-out reflective coating.

[0051] For example, the first region is the central region of the silicon-based backplane of the liquid crystal device. This region has no metasurface structure, and the deflection angle scanning from -B to B is achieved by relying on the liquid crystal driving of the device itself. Then, the light beam is selectively irradiated onto other regions of the liquid crystal device (which have metasurface structures) through a reflector for second-level light modulation. Because the metasurface structure introduces a pretilt angle, the overall scanning range of the liquid crystal device can be expanded from -B to B to AB to A+B. Different pretilt angles A (e.g., -90° to 90°) can be generated by fabricating micro / nano structures with different designs.

[0052] In conjunction with the second aspect, in some implementations of the second aspect, the optical modulation device is applied to a wavelength selective switch (WSS).

[0053] For example, this optical modulation device can also be applied to fields such as vehicle lights, lidar, optical switching, autonomous driving, laser projection, laser display, and laser processing, and this application does not specifically limit it.

[0054] Thirdly, an optical modulation system is provided, comprising: the optical modulation device described in the second aspect or any possible implementation thereof.

[0055] Fourthly, a method for modulating a liquid crystal device is provided, comprising: incident light irradiating a first region of the liquid crystal device to perform first-level light modulation; and the modulated incident light passing through a reflective device to irradiate a second region of the liquid crystal device to perform second-level light modulation.

[0056] The liquid crystal device includes a silicon-based backplane, a liquid crystal layer, a transparent cover plate, a metasurface structure, and a cladding layer. The transparent cover plate is located on the liquid crystal layer, the liquid crystal layer is located between the transparent cover plate and the cladding layer, the cladding layer is located between the metasurface structure and the liquid crystal layer, and the metasurface structure is located between the cladding layer and the silicon-based backplane. Any two metasurface structures are located in different regions on the silicon-based backplane, that is, the metasurface structures in the second region are different from those in the first region.

[0057] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the metasurface structure comprises multiple cells, each of which comprises multiple micro / nano structures, and the surface area of ​​the multiple micro / nano structures gradually increases along the same direction.

[0058] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the liquid crystal device includes multiple metasurface structures, wherein any two metasurface structures are located in different regions of the silicon-based backplane, and the cell periods of any two metasurface structures are different.

[0059] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the liquid crystal device is a silicon-based liquid crystal (LCoS) device.

[0060] In conjunction with the fourth aspect, in some implementations of the fourth aspect, an electrode layer #1 is included on the side of the transparent cover plate closest to the liquid crystal layer. The electrode layer #1 serves to protect the liquid crystal layer and to allow light signals to pass through while also conducting electricity.

[0061] In conjunction with the fourth aspect, in some implementations of the fourth aspect, electrode layer #1 is an indium tin oxide (ITO) layer. The ITO layer possesses excellent conductivity and transparency, enabling light signals to pass through while conducting electricity.

[0062] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the silicon-based backplane includes a driving circuit, a reflective layer, and a passivation layer, with the reflective layer and passivation layer located between the metasurface structure and the driving circuit.

[0063] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the number of micro / nano structures within the cells of any two metasurface structures is different.

[0064] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the sizes of the micro / nanostructures within the cells of any two metasurface structures are different, and the size range of the micro / nanostructures is related to the wavelength of the incident light. Specifically, the size of the micro / nanostructure is greater than or equal to one-quarter of the incident light wavelength and less than or equal to one-half of the incident light wavelength.

[0065] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the shape of the micro / nanostructure includes at least one of rectangular, cylindrical, or elliptical cylindrical shapes.

[0066] In conjunction with the fourth aspect, in some implementations of the fourth aspect, the material of the micro / nano structure includes at least one of gold, silver, aluminum, silicon, gallium nitride, or titanium oxide.

[0067] Fifthly, a method for fabricating a liquid crystal device is provided, characterized by comprising: providing a silicon-based backplate and a liquid crystal layer; fabricating a transparent cover plate on the liquid crystal layer; fabricating a metasurface structure and a coating layer on the silicon-based backplate, wherein the coating layer is disposed between the metasurface structure and the liquid crystal layer.

[0068] In a sixth aspect, a wavelength selective switch (WSS) is provided, comprising: M input ports, a liquid crystal device as described in the first aspect or any possible implementation thereof, and N output ports.

[0069] The optical signal is input from at least one of the M input ports, modulated by the LCoS device, and output from at least one of the N output ports. M and N are positive integers, and at least one of M and N is greater than 1.

[0070] It should be understood that the liquid crystal device (e.g., silicon-based liquid crystal LCoS device) disclosed in this application can be used in WSS, and belongs to optical switching device, which realizes the output of input optical signal from different ports through dimming engine.

[0071] In a seventh aspect, a lidar is provided, comprising: the liquid crystal device described in the first aspect or any possible implementation thereof.

[0072] Eighthly, a chip is provided, comprising: the liquid crystal device described in the first aspect or any possible implementation thereof. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of the structure of the liquid crystal device 100 provided in the embodiments of this application.

[0074] Figure 2 This is a schematic diagram of the cell structure of the metasurface structure provided in the embodiments of this application.

[0075] Figure 3 This is a schematic diagram of the beam scanning range adjusted by the liquid crystal device provided in the embodiments of this application.

[0076] Figure 4 This is a schematic diagram of the structure of the silicon-based backplane 107 partitions of the liquid crystal device provided in the embodiments of this application.

[0077] Figure 5 This is a schematic diagram of the structure of the two-stage optical modulation system 500 provided in the embodiments of this application.

[0078] Figure 6 This is a schematic flowchart of the liquid crystal device modulation method 600 provided in the embodiments of this application.

[0079] Figure 7 This is a schematic diagram of the wavelength selective switch WSS 700 provided in the embodiments of this application. Detailed Implementation

[0080] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0081] The technical solutions provided in this application can be applied to various communication systems that can use light beams (or signal light) to transmit data, such as optical switching, autonomous driving, digital central networks, microwave photonics, liquid crystal antennas, optical phased arrays, beamforming, beam scanning, lidar, laser projection, laser display, laser television, holographic display, adaptive optics, laser beam shaping, laser processing, ultrafast laser pulse shaping, active laser imaging, optical tomography, and retinal imaging.

[0082] Beam deflection technology is a technique for precisely controlling the propagation direction of a light beam. Optical phased array technology holds a unique advantage among various beam deflection technologies due to its miniaturization, simultaneous multi-channel control, and electronic programmable control. It achieves this by modulating the wavefront phase, causing the beam to deflect in a specific direction to achieve beam scanning. Currently, traditional mechanical mirror technology suffers from drawbacks such as large size, poor stability, high power consumption, slow response speed, and difficulty in integrating with driving voltages, which greatly limits the development of space optics and information optics. Therefore, researching novel non-mechanical beam deflection technologies is particularly important.

[0083] For example, a phase-type LCoS, as a liquid crystal optical phased array device, is a hybrid optoelectronic chip composed of a silicon-based circuit backplane and liquid crystal optical elements. It can produce an effect equivalent to a grating after incident light propagation, achieving high-resolution spatial light phase modulation. In practical applications, the phase-type LCoS device only modulates the spatial phase of the incident light without affecting its amplitude; therefore, the beam energy is theoretically not lost, resulting in high optical energy efficiency. This device can add the same phase tilt to the wavefront of the light field every 2π cycles, producing an effect equivalent to a grating after incident light propagation, ultimately changing the beam propagation direction.

[0084] Specifically, the principle of beam scanning using liquid crystal phased array devices originates from microwave phased arrays. By controlling the phase relationship between the emitted light waves of adjacent array elements, a stepped blazed grating with a controllable wedge angle can be simulated, causing the incident beam to undergo constructive interference in a specific direction in the far field after passing through the device, thereby generating a beam with high energy convergence in that direction. Therefore, using a periodic blazed grating model, the beam deflection can be controlled by changing the number of steps in each period, i.e., changing the voltage phase difference. This implementation method can change the direction of light wave propagation in real time and with precision by controlling the electric field intensity, and has advantages such as low driving voltage, small mass, and small size.

[0085] According to the blazed grating formula tanθ = λ / T, the beam polarization angle θ is inversely proportional to the grating period T, where λ represents the incident light wavelength. Therefore, large-angle beam deflection requires a small phase period in the liquid crystal phased array (LCO) device. Considering the limitations of LCoS backplane chip design and fabrication processes, the current minimum pixel size is 3.74 μm, thus supporting a maximum beam deflection angle of only about 10°, which is difficult to increase further. Furthermore, when a voltage is applied to the LCoS phased array, the phase cannot be quickly reset from 2π to 0, instead generating a falling back region, which significantly affects beam deflection efficiency. As the LCoS deflection angle increases, the grating period decreases, and the back region of the device increases, leading to a significant decrease in diffraction efficiency and an increase in insertion loss, which further limits the maximum deflection angle of the LCoS.

[0086] In summary, while liquid crystal optical phased array (LCoS) devices can achieve high-precision, non-mechanical, and stable beam scanning within a certain range, their large pixel size and optical return region limit the deflection angle, resulting in high insertion loss at large deflection angles. Therefore, achieving large-angle deflection in LCoS devices while maintaining low insertion loss is a pressing issue that needs to be addressed.

[0087] In view of this, the present application proposes a liquid crystal device (e.g., an LCOS device) that supports low insertion loss and large-angle deflection. By introducing a pretilt angle through the fabrication of an extremely thin (subwavelength level) metasurface structure with beam deflection function on a silicon-based backplane, the beam scanning range of the device can be flexibly adjusted. Simultaneously, a two-stage optical modulation system can be used to comprehensively extend the beam deflection capability of the liquid crystal device. Furthermore, the liquid crystal device disclosed in this application does not rely on the modulation of the liquid crystal layer in traditional LCoS devices; therefore, its diffraction efficiency and insertion loss are no different from those of traditional LCoS devices.

[0088] To facilitate understanding of the embodiments of this application, the following points are made:

[0089] In the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Here, A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0090] In the embodiments of this application, "when..." means that the device will make corresponding processing under certain objective circumstances. It is not a time limit, nor does it require the device to make a judgment action when implementing it, nor does it mean that there are other limitations.

[0091] It is understood that the terms "first," "second," and various numerical designations (e.g., #1, #2) used in the embodiments shown below are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The sequence numbers of the processes below do not imply the order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0092] The technical solution provided in this application will be described in detail below with reference to the accompanying drawings.

[0093] Figure 1 This is a schematic diagram of the structure of the liquid crystal device 100 provided in an embodiment of this application. Figure 1As shown, taking a silicon-based liquid crystal (LCoS) device as an example, the liquid crystal device 100 includes: a transparent cover plate 101, a liquid crystal layer 102, a silicon-based backplate 107, a metasurface structure 104, and a coating layer 103.

[0094] The transparent cover plate 101 is located on the liquid crystal layer 102, the metasurface structure 104 and the coating layer 103 are located on the silicon-based backplate 107, the liquid crystal layer 102 is located between the transparent cover plate 101 and the coating layer 103, and the coating layer 103 is located between the metasurface structure 104 and the liquid crystal layer 102.

[0095] It should be noted that the metasurface structure in the embodiments of this application can also be called a metasurface structure, and this application does not specifically limit it. It should be understood that silicon is a material that can be used as a substrate for almost all semiconductor devices and integrated circuits. Therefore, the main material in the silicon-based backplane 107 is silicon, and optionally, some other metal materials may be doped into the silicon-based backplane.

[0096] It should be understood that metasurface structures are micro / nanostructures with lateral subwavelength scales, capable of modulating phase gradients from 0 to 2π on thin film layers less than one optical wavelength, thereby enabling flexible and effective control over the phase, polarization, and propagation modes of light and electromagnetic waves. Furthermore, the subwavelength thickness of metasurface structures makes them even more advantageous for applications in integrated optics.

[0097] For example, the materials of the metasurface structure 104 and the cladding layer 103 are different. For example, the material of the metasurface structure 104 can be silicon, and the material of the cladding layer 103 can be silicon oxide or silicon nitride.

[0098] Specifically, the metasurface structure 104 is used to adjust the deflection angle of the optical signal. The coating layer 103 is used to flatten the metasurface structure 104. Flattening refers to filling the surface of the micro / nano structure (metasurface structure 104) to make its surface flat, which is beneficial for compatibility with the subsequent encapsulation process of the liquid crystal layer 102.

[0099] For example, the liquid crystal device 100 is a silicon-based liquid crystal (LCoS) device. It should be understood that LCoS technology utilizes the principle of liquid crystal gratings to adjust the reflection angle of light of different wavelengths to achieve the purpose of light separation.

[0100] Alternatively, the liquid crystal device is a liquid crystal display (LCD).

[0101] In one possible implementation, the silicon-based backplane 107 includes a driving circuit 106, a reflective layer, and a passivation layer 105.

[0102] The reflective layer and passivation layer 105 are located between the metasurface structure 104 and the driving circuit 106.

[0103] For example, the reflective layer can be made of aluminum (Al) to improve the reflectivity of the silicon-based backplane. The passivation layer can be made of dielectric materials such as SiO2 or SiN to prevent Al metal oxidation.

[0104] Optionally, the driving circuit 106 is a CMOS chip.

[0105] Optionally, the silicon-based backplane 107 further includes an electrode layer #2 and a pixel array. The driving circuit 106, electrode layer #2, pixel array, reflective layer, and passivation layer 105 can be integrated on the silicon-based backplane 107; or, the electrode layer #2 and pixel array are integrated on the driving circuit 106, and the driving circuit 106, reflective layer, and passivation layer 105 are integrated on the silicon-based backplane 107.

[0106] The pixel array can include multiple pixels, each of which can be independently adjusted to control the phase of the liquid crystal within the pixel. The pixel array can be an aluminum (Al) layer, for example, comprising 1952×1088 pixels.

[0107] For example, the modulator of the LCoS device modulates the pixels in the pixel array and applies the voltage on the modulated pixels to the liquid crystal layer 102 through the electrode layer #2, so that the refractive index of the corresponding pixel liquid crystal changes, thereby changing the phase of the reflected light by modulating the refractive index of the liquid crystal.

[0108] In one possible implementation, the transparent cover 101 includes an electrode layer #1 on the side closest to the liquid crystal layer 102.

[0109] Electrode layer #1 is used to protect the liquid crystal layer and to allow light signals to pass through and conduct electricity.

[0110] Optionally, electrode layer #1 is an indium tin oxide (ITO) layer. The ITO layer has excellent conductivity and transparency, allowing light signals to pass through while also conducting electricity.

[0111] For example, an electrode layer #2 is included between the liquid crystal layer 102 and the covering layer 103. That is, the liquid crystal layer 102 includes a guiding material that can fix the alignment direction of the liquid crystal molecules under zero voltage. Therefore, there are electrode layers on both the top and bottom sides of the liquid crystal layer 102. For example, electrode layer #1 is the negative electrode and electrode layer #2 is the positive electrode.

[0112] Specifically, when there is no voltage on the liquid crystal layer 102, the liquid crystal crystals are aligned in parallel. As the voltage gradually increases and reaches the threshold voltage, the liquid crystal crystals will rotate at a certain angle. Because the liquid crystal undergoes birefringence under the action of an electric field, different electric field strengths will cause the liquid crystal crystals to rotate to different degrees, thereby changing their refractive index and achieving the purpose of phase modulation of the light beam.

[0113] In other words, the liquid crystal device 100 applies a voltage between the reflective layer 105 and the transparent cover plate 101 through the driving circuit 106, thereby controlling the orientation of the liquid crystal molecules in the liquid crystal layer 102 (i.e., the rotation angle of the main axis of the liquid crystal molecules). This causes the liquid crystal molecules to deflect under the influence of the liquid crystal driving voltage, thus achieving phase modulation of the light beam. Therefore, by controlling the electric field strength, the direction of light wave propagation can be changed in real time and accurately, offering advantages such as low driving voltage, small mass, and small size.

[0114] In one possible implementation, the metasurface structure comprises multiple cells, each of which includes multiple micro / nanostructures, the surface area of ​​which gradually increases along the same direction.

[0115] It should be understood that micro- and nanostructures are ultrathin structures with subwavelength scale. Each micro- and nanostructure has a specific phase delay for incident light, and the size and spatial arrangement of different micro- and nanostructures can generate specific phase gradients.

[0116] Specifically, the surface area of ​​multiple micro- and nanostructures gradually increases along the same direction, which can be understood as the geometric parameters (e.g., radius R, side length (e.g., length and width), perimeter) of multiple micro- and nanostructures gradually increasing along the same direction.

[0117] For example, Figure 2 This is a schematic diagram of the cell structure of the metasurface structure 104 provided in the embodiments of this application. For example... Figure 2 As shown, the example is a cylindrical metasurface structure.

[0118] Specifically, the unit cell of the metasurface structure comprises multiple micro / nanostructures with different geometric dimensions. The cylinder diameters of the different micro / nanostructures gradually increase from R0 to R7, and the corresponding phases gradually increase from 0 to 2π. As shown by the arrows, the phase delay gradually changes from left to right due to the different sizes of the micro / nanostructures, ultimately achieving the effect of beam deflection.

[0119] It should be understood that each micro / nanostructure has a specific phase delay for incident light. Therefore, by adjusting the geometric parameters of the micro / nanostructure (e.g., the diameter R of the cylinder), the phase delay of the incident light can be flexibly adjusted. Arranging micro / nanostructures with different phase delays in space can generate a specific phase gradient in the horizontal direction, ensuring flexible adjustment of the deflection of the incident light propagation direction.

[0120] It should be understood that the shapes and geometric dimensions of the different micro- and nanostructures provided above are merely illustrative and should not be construed as limiting this application.

[0121] Optionally, the shape of the micro / nanostructure includes at least one of rectangular, cylindrical, or elliptical cylindrical shapes.

[0122] Alternatively, the material of the micro / nano structure includes at least one of gold, silver, aluminum, silicon, gallium nitride, or titanium oxide.

[0123] In other words, the shape and material of micro- and nanostructures within the same cell, or within cells of different metasurface structures, can be the same or different, and this application does not impose specific limitations on this. However, from the perspective of CMOS process design, the shape and material of multiple micro- and nanostructures within the same cell are usually the same.

[0124] For example, when the shape of the micro / nano structure is rectangular, the corresponding geometric parameters can be length, width, or perimeter; when the shape of the micro / nano structure is cylindrical, the corresponding geometric parameters can be R or perimeter.

[0125] In this implementation, the metasurface structure is generally arranged periodically according to cells. That is, the periods of multiple cells of the same metasurface structure are usually the same, and the geometric parameters of multiple micro- and nanostructures within each cell gradually change along the same direction. For example, if metasurface structure #1 includes cells #1 and #2, then cells #1 and #2 each include 6 micro- and nanostructures, and the surface area of ​​these 6 micro- and nanostructures increases sequentially within the cell along the same direction (e.g., from left to right).

[0126] In one possible implementation, the number of micro / nano structures within the cells of any two metasurface structures is different.

[0127] For example, the cell of metasurface structure #1 includes 10 micro / nano structures, and the cell of metasurface structure #2 includes 8 micro / nano structures.

[0128] Based on the above scheme, the pretilt angle A can be adjusted by changing the number of micro-nano structures, thereby generating different phase gradients to achieve beam deflection in different ranges, such as -90 to 90°.

[0129] In one possible implementation, the sizes of the micro / nano structures within the cells of any two metasurface structures are different, and the sizes of the micro / nano structures are related to the wavelength of the incident light.

[0130] It should be understood that the size of micro / nano structures is related to the wavelength of incident light. It can be understood that the size of micro / nano structures generally varies from λ / 4 to λ / 2, where λ is the wavelength of incident light. That is, the size of micro / nano structures is greater than or equal to one-quarter of the wavelength of incident light and less than or equal to one-half of the wavelength of incident light.

[0131] In the technical solution of this application, the pretilt angle A can be adjusted by changing the size of the micro-nano structure, thereby generating different phase gradients to achieve beam deflection in different ranges, such as -90 to 90°.

[0132] Considering that micro-nano structures of different sizes have specific phase delays, different micro-nano structures can generate different phase gradients in different regions on the silicon-based backplane 107. Therefore, a beam deflection angle range of -90° to 90° can be achieved by using the metasurface structure 104.

[0133] Since liquid crystal devices can achieve scanning of a small angle range of light beam by dynamically adjusting the liquid crystal, the scanning range of the liquid crystal device can be flexibly adjusted by combining the static pretilt angle A (-90° to 90°) introduced by the metasurface.

[0134] For example, Figure 3 This is a schematic diagram of the beam scanning range adjustable by the liquid crystal device 100 provided in this application embodiment. Figure 3 .

[0135] like Figure 3 As shown, assuming the scanning angle of the liquid crystal modulation of the liquid crystal layer 102 itself is -B to B, the fabrication of micro-nano structures (i.e., metasurface structures 104) on the silicon-based backplate 107 can achieve a fixed deflection angle (i.e., pretilt angle) of A (solid arrow). By using the dynamic angle deflection adjustment of the LCoS device from -B° to B°, the beam deflection scanning of the LCoS device from the angle range of AB to A+B can be finally realized (dashed arrow).

[0136] Specifically, taking a scanning angle B = 7° for liquid crystal layer 102 as an example, such as Figure 3 As shown in (a), the reflected light from the metasurface structure 104 has a fixed deflection angle A = 7°, so the beam deflection scanning range of the liquid crystal device can be adjusted from 0° to 14°. Figure 3 As shown in (b), the reflected light from the metasurface structure 104 has a fixed deflection angle A = 21°, so the beam deflection scanning range of the liquid crystal device can be adjusted from 14° to 28°. Figure 3 As shown in (c), the reflected light of the metasurface structure 104 is fixed at a deflection angle A = 35°, so the beam deflection scanning range of the liquid crystal device can be adjusted to 28° to 42°.

[0137] It should be noted that the beam scanning range of the liquid crystal device provided above is merely an illustrative example and should not be construed as limiting this application.

[0138] To expand the beam scanning range of the liquid crystal device, micro- and nanostructures with different geometries can be fabricated in different regions of the silicon-based backplane 107 to adjust the pretilt angle A, thereby achieving different dynamic deflection angle ranges. Simultaneously, a two-stage optical modulation system (e.g., LCoS1 and LCoS2) can be used to comprehensively extend the beam deflection capability of the LCoS device.

[0139] In one possible implementation, the liquid crystal device includes multiple metasurface structures, wherein any two metasurface structures are located in different regions of a silicon-based backplane, and the cells of any two metasurface structures have different periods.

[0140] Specifically, according to the blazed grating formula tanθ=λ / T, the beam deflection angle θ is inversely proportional to the grating period T. Here, λ represents the incident light wavelength.

[0141] The beam deflection angle θ can be flexibly adjusted by changing the phase gradient. Different phase gradients (e.g., 0 to 2π) can be generated by utilizing the different periods of the cells of the metasurface structure, thereby introducing different pretilt angles (A) to achieve beam deflection in the range of -90° to 90°.

[0142] For example, metasurface structure #1 includes cell #1 and cell #2, each comprising 10 micro / nano structures with sizes gradually increasing from 1 nm to 10 nm and a phase gradient of 0–2π. Similarly, metasurface structure #2 includes cell #3 and cell #4, each comprising 8 micro / nano structures with sizes gradually increasing from 1 nm to 8 nm and a phase gradient of 0–π. In this case, the cell periods of metasurface structure #1 (cell #1) and metasurface structure #2 (cell #3) are different.

[0143] For example, Figure 4 This is a schematic diagram of the partitioned structure of the silicon-based backplane 107 of the liquid crystal device 100 provided in this embodiment of the application. Figure 4 As shown, the silicon-based backplane 107 of the liquid crystal device 100 (e.g., LCoS device) is divided into three columns and three rows, totaling nine regions.

[0144] Specifically, the central region of the silicon-based backplate 107 has no metasurface structure, and the liquid crystal driving mechanism of the liquid crystal device itself can achieve a beam deflection angle scan from -B to B. Metasurface structures 104 are fabricated in the three regions on the left side of the silicon-based backplate 107, which can correspondingly generate pretilt angles A1 = -B, A2 = -3B, and A3 = -5B, enabling beam deflection scanning of the liquid crystal device within the ranges of -2B to 0, -4B to -2B, and -6B to -4B. Similarly, metasurface structures 104 are fabricated in the three regions on the right side of the silicon-based backplate 107, which can correspondingly generate pretilt angles A4 = B, A5 = 3B, and A6 = 5B, enabling beam deflection scanning of the liquid crystal device within the ranges of 0 to 2B, 2B to 4B, and 4B to 6B.

[0145] In other words, the liquid crystal device 100, based on the traditional LCoS device structure, integrates a subwavelength metasurface structure 104 with beam deflection function onto a silicon-based backplane 107 to achieve pre-tilt of the beam propagation direction. The specific beam deflection angle A can be flexibly adjusted through different designed micro / nano structures (e.g., by changing the size, material, and spatial arrangement of the micro / nano structures), ultimately achieving beam deflection scanning in the range of AB to A+B.

[0146] It should be noted that the beam scanning range and spatial arrangement of the liquid crystal device provided above are merely illustrative examples and should not be construed as limiting this application.

[0147] In one possible implementation, the liquid crystal device also includes a reflective device.

[0148] The reflective device is used to direct the incident light, after the first stage of light modulation, onto a second region of the liquid crystal device for second-stage light modulation. The first stage of light modulation is based on the incident light illuminating a first region of the liquid crystal device, and the second region is located in a different region from the first region on the silicon-based backplane.

[0149] For example, the reflective device may be a lens, and one side of the lens has a reflective coating with a central cutout.

[0150] By subjecting incident light twice to two different regions of the silicon-based backplane of a liquid crystal device for two-stage optical modulation, the overall beam deflection capability of the liquid crystal device can be expanded. For example, the angle range of the first-stage optical modulation is -B to B, and the angle range of the second-stage optical modulation is AB to A+B, where A is the pretilt angle introduced by the metasurface structure.

[0151] For example, Figure 5 This is a schematic diagram of the two-stage optical modulation system 500 provided in an embodiment of this application. The explanation uses an LCoS device as an example. Figure 5 As shown, the optical modulation system 500 includes an LCoS device (i.e., an example of a liquid crystal device 100) and a lens, with a reflective coating with a central cutout on one side of the lens.

[0152] Specifically, incident light enters from the center of the lens, passes through the coated reflector in the central hollow section, and illuminates the central region of the LCoS for first-stage light modulation. The reflection angle of the beam can be flexibly adjusted by regulating the liquid crystal in the central region of the LCoS (e.g., the adjustment range is -B to B). Then, a coated reflector on one side of the lens selectively illuminates other different regions of the LCoS for second-stage light modulation, achieving beam scanning within other angle ranges.

[0153] It should be understood that the central region for first-level optical modulation has no metasurface structure 104, while other regions for second-level optical modulation have metasurface structures 104, and each of these other regions may have different metasurface structures 104; this application does not specifically limit this. Because the metasurface structures in different regions are different, the introduced pretilt angle A is also different (e.g., A1 or A2), thus the beam scanning range of the entire LCoS device is also different, and it has multiple scanning ranges (e.g., A1-B to A1+B or A2-B to A2+B), thereby expanding the overall beam deflection capability of the LCoS device.

[0154] Therefore, the optical modulation system 500, based on the liquid crystal device 100, can achieve a larger angle deflection. For example, the beam scanning range can be expanded from the conventional -B to B to -6B to 6B.

[0155] It should be understood that Figure 5 The optical modulation system 500 shown is merely illustrative and should not be construed as limiting this application. The optical modulation system 500 may also include other optical path alteration devices such as mirrors, beam splitters, and collimators.

[0156] The liquid crystal device 100 disclosed in this application, taking an LCoS device as an example, introduces a beam pretilt angle (A) by fabricating one or more metasurface structures 104 between a silicon-based backplate 107 and a liquid crystal layer 102, thereby achieving pretilt of the beam propagation direction. Compared with conventional LCoS devices, this provides an additional degree of freedom in adjusting the beam deflection angle, allowing for flexible adjustment of the dynamic scanning range of the device's beam deflection angle by changing the degree of the pretilt angle. Combining the static deflection of the beam by the metasurface structure 104 with the dynamic beam deflection scanning (-B to B) of the liquid crystal layer 102 in conventional LCoS devices, the overall beam angle scanning range (AB to A+B) is broadened. Based on this, by fabricating metasurface structures 104 with different pretilt angles in different regions of the silicon-based backplate 107, and then utilizing a two-stage modulation optical modulation system 500, the maximum deflection angle of the liquid crystal device 100 can be significantly improved. Furthermore, the large-angle beam scanning function of the liquid crystal device 100 disclosed in this application originates from the introduction of the metasurface structure 104, and does not rely on the modulation of the liquid crystal layer 102. Its diffraction efficiency and insertion loss are no different from those of conventional devices, thus not introducing additional insertion loss and maintaining a low value. That is, it is possible to significantly increase the scanning angle range of the device while maintaining low insertion loss.

[0157] It should be understood that Figure 1The dimensions, positions, and specific shapes of the transparent cover plate 101, liquid crystal layer 102, cladding layer 103, metasurface structure 104, reflective / passivation layer 105, driving circuit 106, and silicon-based backplate 107 shown are illustrative and should not constitute any limitation on this application.

[0158] Based on the above Figure 1 The liquid crystal device shown (e.g., the novel LCoS device 100), Figure 6 This is a schematic flowchart of the liquid crystal device modulation method 600 provided in an embodiment of this application. Figure 6 As shown, it specifically includes the following two steps.

[0159] S610, incident light irradiates the first region of the liquid crystal device to perform first-level light modulation.

[0160] The liquid crystal device includes a silicon-based backplate, a liquid crystal layer, a transparent cover plate, a metasurface structure, and a cladding layer. The liquid crystal layer is located between the transparent cover plate and the cladding layer, the cladding layer is located between the metasurface structure and the liquid crystal layer, and the metasurface structure is located between the cladding layer and the silicon-based backplate. The metasurface structure in the second region is different from that in the first region.

[0161] In other words, any two metasurface structures are located in different regions on the silicon-based backplane. It should be understood that the first region and the second region can be considered as different regions on the silicon-based backplane, for example, see [reference needed]. Figure 4 The schematic diagram of the partitioned structure of the silicon-based backplane shown illustrates that the metasurface structures in the first and second regions differ. This can be understood as the micro / nanostructures within the cells of the metasurface structures in the two regions having different sizes, materials, shapes, and periods. In short, integrating subwavelength-level metasurface structures with beam deflection capabilities onto the silicon-based backplane generates a pre-tilt angle A, enabling pre-tilt of the beam propagation direction. The specific beam deflection angle A can be flexibly adjusted using different designed micro / nanostructures (e.g., by changing the size, material, and spatial arrangement of the micro / nanostructures), ultimately achieving beam deflection scanning over a wide angle range.

[0162] For example, the metasurface structure includes multiple cells, each of which includes multiple micro / nano structures, and the surface area of ​​the multiple micro / nano structures gradually increases along the same direction.

[0163] Optionally, the liquid crystal device includes multiple metasurface structures, wherein any two metasurface structures are located in different regions of the silicon-based backplane, and the cell periods of any two metasurface structures are different.

[0164] Optionally, the number of micro / nano structures within the cells of any two metasurface structures may differ.

[0165] Optionally, the sizes of the micro / nano structures within the cells of any two metasurface structures are different, wherein the size of the micro / nano structure is greater than or equal to one-quarter of the incident light wavelength and less than or equal to one-half of the incident light wavelength.

[0166] S620, the modulated incident light passes through the reflective device and illuminates the second region of the liquid crystal device to perform second-level light modulation.

[0167] For example, the reflective device can be a lens, and one side of the lens has a reflective coating with a central cutout. It should be understood that a reflective device is any device with a reflective function, as long as it can reflect the light modulated in the first stage to the second region for second-stage light modulation. This application does not make any specific limitations in this regard.

[0168] It should be understood that the description of the method embodiments corresponds to the description of the apparatus embodiments; therefore, any parts not described in detail can be referred to the preceding apparatus embodiments.

[0169] Based on the above scheme, by irradiating two different regions of the silicon-based backplane of the liquid crystal device with incident light twice and performing two-stage optical modulation, the overall beam deflection capability of the liquid crystal device can be expanded. For example, the angle range of the first-stage optical modulation is -B to B, and the angle range of the second-stage optical modulation is AB to A+B, where A is the pretilt angle introduced by the metasurface structure.

[0170] In summary, by integrating a subwavelength metasurface structure with beam deflection capabilities onto the silicon backplane of a liquid crystal device based on a traditional LCOS device, pre-tilting of the beam propagation direction is achieved. The deflection angle can be flexibly adjusted through the design of the micro / nano structure (e.g., changing the size, material, and shape of the micro / nano structure). Simultaneously, dynamic beam scanning is achieved near the pre-tilt angle introduced by the metasurface structure by driving the liquid crystal using LCoS. Furthermore, metasurface structures with different pre-tilt angles are fabricated in different regions of the silicon backplane, and a two-stage dimming system is used to significantly increase the maximum deflection angle of the liquid crystal device. Therefore, the method disclosed in this application supports large-angle beam scanning while maintaining low insertion loss.

[0171] Liquid crystal on silicon (LCoS), a reflective spatial light modulator based on a silicon backplane, combines liquid crystal technology with CMOS technology. With optical phase modulation as its core, it is widely used in fields including but not limited to optical communication, displays, automotive lighting, LiDAR, optical switching, autonomous driving, laser projection, laser display, and laser processing. Due to its excellent passband tuning flexibility, optical network hardware compatibility, and beam deflection stability, LCoS is increasingly being used in wavelength selective switching (WSS).

[0172] For example, Figure 7This is a schematic diagram of the structure of WSS 700 provided in the embodiments of this application, that is, the application scenario of driving modulation of liquid crystal device 100 (e.g., LCoS device).

[0173] like Figure 7 As shown, the N×N WSS includes N input ports 701, LCoS1 702, N output ports 703, LCoS2 705, and a lens 704. This WSS enables all-optical connections between any pair of input and output ports. In other words, for any wavelength optical signal from the N input ports, after modulation by driving, it can be output from any one of the N output ports.

[0174] It should be understood that the WSS provided in this application embodiment modulates the phase of the optical signal twice through LCOS1 702 and LCoS2 705, thereby changing the transmission direction of the optical signal.

[0175] For example, an optical signal can be input from at least one input port 1 among N input ports 701, modulated and selected by LCOS1 702, irradiated by lens 704, and then reflected by lens 704 and irradiated by LCOS2 705 for modulation. Finally, the modulated optical signal is output from at least one output port N among N output ports 703, thereby completing the change of optical signal transmission direction, such as completing optical signal exchange, uploading or downloading.

[0176] Specifically, different regions on the silicon-based backplanes of LCOS1 702 and LCOS2 705 are prepared with metasurface structures 104 of different designs. The specific dimensions, quantities, materials, etc. can be found in the description of the liquid crystal device 100 above. For the sake of brevity, they will not be repeated here.

[0177] Optionally, the input / output ports can be made of optical fibers, and the input / output ports can form an input / output fiber array.

[0178] It should be understood that Figure 7 The statement that the number of input ports and output ports are equal is merely illustrative. In a specific implementation, the number of input ports and output ports may be equal or unequal, and this application does not impose any specific limitations on this.

[0179] It should also be understood that Figure 7 The structural diagram of the WSS shown is for illustrative purposes only, and this application is not limited thereto. For example, the WSS may also include optical path alteration devices such as lenses, mirrors, beam splitters, and collimators.

[0180] It should be understood that the specific examples in the embodiments of this application are only to help those skilled in the art better understand the technical solutions of this application, and the above specific implementation methods can be considered as the optimal implementation methods of this application, rather than limiting the scope of the embodiments of this application.

[0181] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0182] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0183] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0184] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0185] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0186] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0187] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations 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 scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A liquid crystal device, characterized in that, include: A silicon-based backplane, a liquid crystal layer, a transparent cover plate, a metasurface structure, and a coating layer, wherein the liquid crystal layer is located between the transparent cover plate and the coating layer, the coating layer is located between the metasurface structure and the liquid crystal layer, and the metasurface structure is located between the coating layer and the silicon-based backplane; The liquid crystal device further includes a reflective device for irradiating the incident light that has completed the first-level light modulation onto a second region of the liquid crystal device to perform a second-level light modulation; wherein the first-level light modulation is based on the incident light irradiating the first region of the liquid crystal device, and the second region and the first region are located in different regions of the silicon-based backplane.

2. The liquid crystal device according to claim 1, characterized in that, The liquid crystal device is a silicon-based liquid crystal (LCoS) device.

3. The liquid crystal device according to claim 1 or 2, characterized in that, The transparent cover plate includes an electrode layer on the side closest to the liquid crystal layer.

4. The liquid crystal device according to claim 3, characterized in that, The electrode layer is an indium tin oxide (ITO) layer.

5. The liquid crystal device according to claim 1 or 2, characterized in that, The silicon-based backplane includes a driving circuit, a reflective layer, and a passivation layer, wherein the reflective layer and the passivation layer are located between the metasurface structure and the driving circuit.

6. The liquid crystal device according to claim 1 or 2, characterized in that, The metasurface structure comprises multiple cells, each of which includes multiple micro / nano structures, and the surface area of ​​the multiple micro / nano structures gradually increases along the same direction.

7. The liquid crystal device according to claim 1 or 2, characterized in that, The liquid crystal device includes a plurality of the metasurface structures, wherein any two metasurface structures are located in different regions of the silicon-based backplane, and the cell periods of any two metasurface structures are different.

8. The liquid crystal device according to claim 7, characterized in that, The number of micro / nano structures within the cells of any two of the aforementioned metasurface structures is different.

9. The liquid crystal device according to claim 7, characterized in that, The sizes of the micro-nano structures within the cells of any two of the metasurface structures are different, wherein the size of the micro-nano structure is greater than or equal to one-quarter of the incident light wavelength and less than or equal to one-half of the incident light wavelength.

10. The liquid crystal device according to claim 6, characterized in that, The shape of the micro / nanostructure includes at least one of rectangular, cylindrical, or elliptical cylindrical shapes.

11. The liquid crystal device according to claim 6, characterized in that, The materials of the micro / nano structures include at least one of gold, silver, aluminum, silicon, gallium nitride, or titanium oxide.

12. An optical modulation device, characterized in that, include: The liquid crystal device as described in any one of claims 1 to 11; as well as A reflective device is used to irradiate the incident light, which has completed the first-level light modulation, onto a second region of the liquid crystal device to perform a second-level light modulation. The first-level light modulation is based on the incident light irradiating the first region of the liquid crystal device, and the second region has a different metasurface structure from the first region.

13. The optical modulation device according to claim 12, characterized in that, The optical modulation device is used in a wavelength selective switch (WSS).

14. An optical modulation system, characterized in that, include: The optical modulation device as described in claim 12 or 13.

15. A method for modulating a liquid crystal device, characterized in that, include: Incident light irradiates a first region of the liquid crystal device to perform first-level light modulation; The modulated incident light is reflected by a reflective device and then irradiates the second region of the liquid crystal device to perform second-level light modulation. The liquid crystal device includes a silicon-based backplane, a liquid crystal layer, a transparent cover plate, a metasurface structure, and a coating layer. The liquid crystal layer is located between the transparent cover plate and the coating layer. The coating layer is located between the metasurface structure and the liquid crystal layer. The metasurface structure is located between the coating layer and the silicon-based backplane. The metasurface structure in the second region is different from that in the first region.

16. The method according to claim 15, characterized in that, The metasurface structure comprises multiple cells, each of which includes multiple micro / nano structures, and the surface area of ​​the multiple micro / nano structures gradually increases along the same direction.

17. The method according to claim 15 or 16, characterized in that, The liquid crystal device includes a plurality of the metasurface structures, wherein any two metasurface structures are located in different regions of the silicon-based backplane, and the cell periods of any two metasurface structures are different.

18. The method according to claim 17, characterized in that, The number of micro / nano structures within the cells of any two of the aforementioned metasurface structures is different.

19. The method according to claim 17, characterized in that, The sizes of the micro-nano structures within the cells of any two of the metasurface structures are different, wherein the size of the micro-nano structure is greater than or equal to one-quarter of the incident light wavelength and less than or equal to one-half of the incident light wavelength.

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