WO2023231859A1 - Liquid crystal device, and optical modulation device and system - Google Patents

Abstract

Provided are a liquid crystal device (100), and an optical modulation device and system, which are applied to the fields of wavelength selective switches, laser radars, unmanned driving, laser display, etc. The liquid crystal device (100) comprises a silicon-based backplane (107), a liquid crystal layer (102), a transparent cover plate (101), a metasurface (104) and a cladding layer (103). The liquid crystal layer (102) is located between the transparent cover plate (101) and the cladding layer (103), the cladding layer (103) is located between the metasurface (104) and the liquid crystal layer (102), and the metasurface (104) is located between the cladding layer (103) and the silicon-based backplane (107). A pre-tilt angle is generated by means of the metasurface (104), and combined with a modulation range of the liquid crystal layer (102) of a traditional liquid crystal on silicon (LCoS) device, an overall beam angle scanning range is extended, that is, a large-angle deflection of the LCoS device is realized, and a low insertion loss is also maintained.

Description

A liquid crystal device, optical modulation device and system

This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on June 2, 2022, with application number 202210621640.9 and the application title "A liquid crystal device, optical modulation device and system", the entire content of which is incorporated by reference incorporated in this application.

Technical field

The present application relates to the field of optical communications, and more specifically, to a liquid crystal device, optical modulation device and system.

Background technique

Beam deflection technology is a technology that accurately controls the direction of beam propagation. Optical phased array technology occupies a unique advantage among many beam deflection technologies due to its characteristics of miniaturization, multi-channel simultaneous control, and electronic control programmability. Its implementation is to modulate the wavefront phase to deflect the beam in a specific direction. To achieve the purpose of beam scanning.

Among them, phase-type liquid crystal on silicon (LCoS), as a liquid crystal optical phased array device, can produce an effect equivalent to a grating after transmitting incident light, achieve high-resolution spatial light phase modulation, and then change the beam. propagation direction. Although the liquid crystal optical phased array device can achieve high-precision, non-mechanical, and stable beam scanning within a certain range, its deflection angle is limited due to the large pixel size and optical return area, and under large-angle deflection It is easy to produce high insertion loss.

Therefore, how to achieve large-angle deflection of LCoS devices and maintain low insertion loss is an urgent problem to be solved.

Contents of the invention

Embodiments of the present application provide a liquid crystal device, an optical modulation device, and a system that can achieve large-angle deflection of incident light and maintain low insertion loss of the device.

In the first aspect, a liquid crystal device is provided, including: a silicon-based backplane, a liquid crystal layer, a transparent cover, a metasurface structure and a coating layer. Among them, 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.

Among them, the metasurface structure and the materials of the cladding layer are different. For example, the material of the metasurface structure may be silicon, and the material of the cladding layer may be silicon oxide or silicon nitride.

It should be noted that in the embodiments of the present application, the metasurface structure (metasurface) may also be called a metasurface structure. It should be understood that the metasurface structure is an ultra-thin micro-nano optical structure with a beam deflection function and a lateral sub-wavelength size. It is used to achieve efficient light focusing and beam shaping, and can be achieved in a thin film structure layer of less than one optical wavelength. It achieves accurate control of the full 2π phase, thereby achieving flexible and effective control of light wave, electromagnetic wave phase, polarization mode, propagation mode and other characteristics.

Specifically, the metasurface structure is used to adjust the deflection angle of the optical signal. Among them, 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 the silicon-based backplane, etc., to ultimately achieve beam deflection in a wide range of angles. scanning. The cladding layer is used to flatten the metasurface structure. Among them, flattening refers to filling the surface of the micro-nano structure (superstructure) to make the surface flat, which is conducive to compatibility with the subsequent packaging process of the liquid crystal layer.

The liquid crystal device disclosed in this application, taking the traditional LCoS device as an example, is prepared between a silicon-based backplane and a liquid crystal layer. One or more layers of metasurface structures introduce a beam pretilt angle (A) to achieve pretilt in the beam propagation direction. Compared with traditional liquid crystal devices, there is one more degree of freedom to adjust the beam deflection angle, making it possible to flexibly adjust the device beam scanning range by changing the degree of the pretilt angle. Utilizing the static deflection of the beam by the metasurface structure and the dynamic deflection scanning of the beam by the liquid crystal layer of the traditional LCoS device (-B~B), the overall beam angle scanning range (AB~A+B) is increased.

In addition, the function of realizing large-angle beam scanning of the liquid crystal device disclosed in this application comes from the introduction of metastructure, and does not rely on the modulation of the liquid crystal layer of the device. Its diffraction efficiency and insertion loss are no different from traditional devices, and can maintain Under the premise of low insertion loss, the scanning angle range of the device is greatly increased.

In conjunction with the first aspect, in some implementations of the first aspect, the liquid crystal device is a liquid crystal on silicon LCoS device.

Optionally, the liquid crystal device is a liquid crystal display (LCD). Among them, the structure of the LCD is to place a liquid crystal cell between two parallel glass substrates, a thin film transistor (TFT) is set on the lower glass substrate, and a color filter is set on the upper glass substrate. By changing the The signal and voltage are used to control the rotation direction of the liquid crystal molecules, thereby controlling whether the polarized light of each pixel is emitted to achieve the display purpose.

In conjunction with the first aspect, in some implementations of the first aspect, a side of the transparent cover close to the liquid crystal layer includes electrode layer #1.

Among them, electrode layer #1 is used to protect the liquid crystal layer, and to transmit optical signals and conduct electricity.

Optionally, electrode layer #2 is included between the liquid crystal layer and the cladding layer. That is to say, the liquid crystal layer includes guiding materials that can fix the alignment direction of liquid crystal molecules under zero voltage conditions. Therefore, there are electrode layers on both sides of the liquid crystal layer. For example, electrode layer #1 is the negative electrode, and electrode layer #2 is the positive electrode.

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

Among them, the ITO layer has good electrical conductivity and transparency, and can transmit optical signals and conduct electricity.

In connection 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, and the reflective layer and the passivation layer are located between the metasurface structure and the driving circuit.

For example, the material of the reflective layer may be aluminum, which is used to improve the reflectivity of the silicon-based backplane. The material of the passivation layer can be dielectric material SiO2 or SiN, which is used to prevent the oxidation of Al metal.

For example, the driving circuit may be a CMOS chip, which is used to apply a voltage between the reflective layer and the transparent cover to drive and modulate the liquid crystal layer (for example, the rotation angle of the liquid crystal molecules) to achieve the purpose of phase modulation of the light beam.

Optionally, the silicon-based backplane also includes electrode layer #2 and a pixel array. Among them, the driving circuit, electrode layer #2, pixel array, reflective layer and passivation layer can be integrated on the silicon-based backplane; alternatively, the electrode layer #2 and pixel array are integrated on the driving circuit, and the driving circuit, reflective layer and The passivation layer is integrated on the silicon-based backplane.

Combined with the first aspect, in some implementations of the first aspect, the metastructure surface structure includes a plurality of unit cells, each of the plurality of unit cells includes a plurality of micro-nano structures, and the surface area of the multiple micro-nano structures gradually increase in the same direction.

It should be understood that micro-nano structures are ultra-thin structures with sub-wavelength dimensions. Each micro-nano structure has a specific phase retardation for incident light. The size and spatial arrangement of different micro-nano structures can generate specific phase gradients.

Among them, the surface areas of multiple micro-nano structures gradually increase along the same direction, which can be understood as: the geometric parameters (for example, radius R, side length (eg, length and width), perimeter) of multiple micro-nano structures gradually increase along the same direction. Increase.

For example, when the shape of the micro-nano structure is a rectangle, the corresponding geometric parameter can be length, width or perimeter; when the shape of the micro-nano structure is cylindrical, the corresponding geometric parameter can be R or the perimeter.

In this implementation, the metasurface structure is generally arranged periodically according to the unit cells, that is, the periods of multiple units of the same metasurface structure are usually the same, and the multiple micro-nano structures in each unit cell are The geometric parameters of gradually change in the same direction change. For example, metasurface structure #1 includes cell #1 and cell #2, then cell #1 and cell #2 respectively include 6 micro-nano structures, and the surface areas of these 6 micro-nano structures are along the inner edge of the cell. increasing in the same direction (for example, from left to right).

In connection with the first aspect, in some implementations of the first aspect, the liquid crystal device includes a plurality of metasurface structures, wherein any two metastructures are located in different areas of the silicon-based backplane, and any two metastructures The cells of the surface structure have different periods.

Specifically, according to the blazed grating formula tanθ=λ/T, it can be concluded that the beam deflection angle θ is inversely proportional to the grating period T. Among them, λ represents the wavelength of incident light.

The beam deflection angle θ can be flexibly adjusted by changing the phase gradient. Using the different periods of the cells of the metastructure surface structure, different phase gradients (for example, 0~2π) can be generated, and then different pretilt angles (A) can be introduced to achieve - Beam deflection in 90° to 90° angle range.

For example, metasurface structure #1 includes unit cell #1 and unit cell #2. Unit cell #1 and unit cell #2 each include 10 micro-nano structures, with the size gradually increasing from 1 nm to 10 nm, and the phase gradient is 0. ~2π. Similarly, metasurface structure #2 includes unit cell #3 and unit cell #4. Unit cell #3 and unit cell #4 each include 8 micro-nano structures, with the size gradually increasing from 1 nm to 8 nm, and the phase gradient is 0. ~π. At this time, the periods of the cells of metasurface structure #1 (cell #1) and metasurface structure #2 (cell #3) are different.

Combined with the first aspect, in some implementations of the first aspect, the number of micro-nano structures in the cells of any two metastructure surface structures is different.

For example, the unit cell of super surface structure #1 includes 10 micro-nano structures, and the unit cell of super surface structure #2 includes 8 micro-nano structures.

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

Combined with the first aspect, in some implementations of the first aspect, the sizes of the micro-nano structures in the cells of any two metastructure surface structures are different, and the size of the micro-nano structures is related to the wavelength of the incident light.

It should be understood that the size of the micro-nano structure is related to the wavelength of the incident light. It can be understood that the size variation range of the micro-nano structure is generally λ/4 to λ/2, where λ is the wavelength of the incident light, that is, the size of the micro-nano structure is greater than Or equal to one quarter of the wavelength of the incident light, and less than or equal to one half of the wavelength of the incident light.

For example, if the wavelength of the incident light is 400 nm, the size range of the micro-nano structure may be 100 nm to 200 nm.

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

In conjunction with the first aspect, in some implementations of the first aspect, the liquid crystal device further includes a reflective device. Among them, the reflective device is used to irradiate the incident light after completing the first-level light modulation to the second area of the liquid crystal device to perform the second-level light modulation. The first level of light modulation is based on the incident light irradiating the first area of the liquid crystal device, and the second area and the first area are located in different areas of the silicon-based backplane.

For example, the reflective device may be a lens, and one side of the lens has a hollow reflective mirror coating.

Based on the above solution, the incident light is irradiated twice to two different areas of the silicon-based backplane of the liquid crystal device for 2-level light modulation, which can overall expand the beam deflection capability of the liquid crystal device. For example, the angle range of the first-level light modulation is -B~B, and the angle range of the second-level light modulation is A-B~A+B, where A is the pretilt angle introduced by the metasurface structure.

In conjunction with the first aspect, in some implementations of the first aspect, the shape of the micro-nano structure includes at least one of a rectangle, a cylinder, or an elliptical cylinder.

That is to say, the shapes of the micro-nano structures in the same unit cell or in units with different superstructure surface structures may be the same or different, and this application does not specifically limit this. However, from the perspective of CMOS process design, the The shapes of multiple micro-nanostructures are usually the same.

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.

In other words, the materials of the micro-nano structures in the same unit cell or in units with different superstructure surface structures may be the same or different, and this application does not specifically limit this. However, from the perspective of CMOS process design, the materials of multiple micro-nano structures in the same unit cell are usually the same.

In a second aspect, an optical modulation device is provided, including: a reflective device, and the liquid crystal device in the above-mentioned first aspect or any possible implementation of the first aspect. Among them, the reflective device is used to irradiate the incident light that completes the first-level light modulation to the second area of the liquid crystal device to perform the second-level light modulation. The first-level light modulation is based on the incident light irradiating the first area of the liquid crystal device. ongoing.

The metasurface structures on the second area and the first area are different, that is to say, the areas where any two metasurface structures are located on the silicon-based backplane are different.

It should be understood that the first region and the second region can be regarded as different regions on the silicon-based backplane. For example, see the schematic structural diagram of the partitions of the silicon-based backplane shown in Figure 4. The superstructures on the first region and the second region The difference in the metasurface structure can be understood as the different sizes, materials, shapes, etc. of the micro-nano structures in the cells of the metasurface structure in the two regions, as well as the different periods of the cells of the metasurface structure.

That is, a sub-wavelength metasurface structure with beam deflection function is integrated into the silicon-based backplane to achieve pre-tilt in the beam propagation direction. Among them, the specific beam deflection angle A (or pretilt angle A) can be flexibly adjusted through differently designed micro-nano structures (for example, by changing the size, material, spatial arrangement, etc. of the micro-nano structures), ultimately achieving a large angle Range of beam deflection scans.

Optionally, the reflective device is a lens, and one side of the lens has a mirror coating with a hollow center.

For example, the first area is the central area of the silicon-based backplane of the liquid crystal device. There is no metasurface structure in this area, and the deflection angle scanning of -B to B is realized by relying on the liquid crystal drive of the device itself. Then, the light beam is selectively irradiated to other areas of the liquid crystal device (which has a metasurface structure) through the reflector for second-level light modulation. Since the metasurface structure introduces a pretilt angle, the overall scanning range of the liquid crystal device can be Expanded from the previous -B~B to A-B~A+B. Among them, different pretilt angles A (for example, -90~90°) can be produced by preparing micro-nano structures of different designs.

Combined with the second aspect, in some implementations of the second aspect, the optical modulation device is applied to a wavelength selective switch (WSS).

For example, the optical modulation device can also be applied to fields such as car lights, lidar, optical switching, driverless driving, laser projection, laser display, laser processing, etc. This application does not specifically limit this.

In a third aspect, an optical modulation system is provided, including: the optical modulation device described in the above second aspect or any possible implementation manner of the second aspect.

In a fourth aspect, a method for modulating a liquid crystal device is provided, including: irradiating incident light to a first region of the liquid crystal device to perform first-level light modulation; and irradiating the modulated incident light to a second region of the liquid crystal device through a reflective device. , for second-level light modulation.

Among them, 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, and the liquid crystal layer is located between the transparent cover plate and the cladding layer. The cladding layer Located between the metasurface structure and the liquid crystal layer, the metasurface structure is located between the cladding layer and the silicon-based backplane. Any two metasurface structures are located in different areas of the silicon-based backplane, that is, the second area It is different from the metasurface structure on the first region.

Combined with the fourth aspect, in some implementations of the fourth aspect, the metastructure surface structure includes multiple unit cells, each of the multiple unit cells includes multiple micro-nano structures, and the surface area of the multiple micro-nano structures gradually increase in the same direction.

Combined with the fourth aspect, in some implementations of the fourth aspect, the liquid crystal device includes multiple metasurface structures, wherein any two metastructures are located in different areas of the silicon-based backplane, and any two metastructures The cells of the surface structure have different periods.

In conjunction with the fourth aspect, in some implementations of the fourth aspect, the liquid crystal device is a liquid crystal on silicon LCoS device.

Combined with the fourth aspect, in some implementations of the fourth aspect, a side of the transparent cover close to the liquid crystal layer includes electrode layer #1. Among them, electrode layer #1 is used to protect the liquid crystal layer, and to transmit optical signals and conduct electricity.

Combined with the fourth aspect, in some implementations of the fourth aspect, electrode layer #1 is an indium tin oxide ITO layer. Among them, the ITO layer has good electrical conductivity and transparency, and can transmit optical signals and conduct electricity.

In connection 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, and the reflective layer and the passivation layer are located between the metasurface structure and the driving circuit.

Combined with the fourth aspect, in some implementations of the fourth aspect, the number of micro-nano structures in the cells of any two metastructure surface structures is different.

Combined with the fourth aspect, in some implementations of the fourth aspect, the sizes of the micro-nano structures in the cells of any two metastructure surface structures are different, and the size range of the micro-nano structures is related to the wavelength of the incident light. Specifically, the size of the micro-nano structure is greater than or equal to one-quarter of the wavelength of the incident light, and less than or equal to one-half of the wavelength of the incident light.

In conjunction with the fourth aspect, in some implementations of the fourth aspect, the shape of the micro-nano structure includes at least one of a rectangle, a cylinder, or an elliptical cylinder.

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.

In a fifth aspect, a method for preparing a liquid crystal device is provided, which is characterized by comprising: providing a silicon-based backplane and a liquid crystal layer; preparing a transparent cover plate on the liquid crystal layer; preparing a metasurface structure on the silicon-based backplane; The coating layer is placed between the metasurface structure and the liquid crystal layer.

In a sixth aspect, a wavelength selective switch WSS is provided, including: M input ports, the liquid crystal device described in the above first aspect or any possible implementation of the first aspect, and N output ports.

Among them, the optical signal is input from at least one input port among M input ports. After being modulated by the LCoS device, it is output from at least one output port among N output ports. M and N are positive integers, and there is at least one of M and N. Greater than 1.

It should be understood that the liquid crystal device disclosed in this application (for example, a liquid crystal on silicon LCoS device) can be applied in WSS and is an optical switching device. The input optical signal is output from different ports through a dimming engine.

In a seventh aspect, a lidar is provided, including: the liquid crystal device described in the first aspect or any possible implementation of the first aspect.

In an eighth aspect, a chip is provided, including: the liquid crystal device described in the above-mentioned first aspect or any possible implementation of the first aspect.

Description of the drawings

FIG. 1 is a schematic structural diagram of a liquid crystal device 100 provided by an embodiment of the present application.

Figure 2 is a schematic structural diagram of a unit cell of a metasurface structure provided by an embodiment of the present application.

FIG. 3 is a schematic diagram of the beam scanning range adjusted by the liquid crystal device provided by the embodiment of the present application.

FIG. 4 is a schematic structural diagram of the partitions of the silicon-based backplane 107 of the liquid crystal device provided by the embodiment of the present application.

FIG. 5 is a schematic structural diagram of a two-stage optical modulation system 500 provided by an embodiment of the present application.

FIG. 6 is a schematic flowchart of a liquid crystal device modulation method 600 provided by an embodiment of the present application.

Figure 7 is a schematic structural diagram of a wavelength selective switch WSS 700 provided by an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

The technical solution provided by this application can be applied to various communication systems that can use light beams (or signal light) to transmit data, such as optical switching, driverless driving, digital center networks, microwave photonics, liquid crystal antennas, and optical phase control. array, beamforming, beam scanning, lidar, laser projection, laser display, laser television, holographic display, adaptive optics, laser beam shaping, laser processing, ultrafast laser pulse shaping, laser active imaging, optical tomography, and retina imaging and other fields.

Beam deflection technology is a technology that accurately controls the direction of beam propagation. Optical phased array technology occupies a unique advantage among many beam deflection technologies due to its characteristics of miniaturization, multi-channel simultaneous control, and electronic control programmability. Its implementation is to modulate the wavefront phase to deflect the beam in a specific direction. To achieve the purpose of beam scanning. Currently, traditional mechanical rotating mirror technology has greatly restricted the development of space optics and information optics due to its large size, poor stability, high power consumption, slow response speed, and difficulty in combining with driving voltage. Therefore, it is particularly important to study new non-mechanical beam deflection technologies.

As an example, 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 transmitting incident light, achieving high resolution. The role of spatial light phase modulation. In practical applications, phase-type LCoS devices only modulate the spatial phase of the incident light without affecting its amplitude. Therefore, the beam energy is theoretically not lost and has high optical energy efficiency. This device can add the same phase tilt to the wavefront of the light field in every 2π period, so that the incident light will produce an effect equivalent to a grating after transmission, and ultimately change the propagation direction of the beam.

Specifically, the principle of using liquid crystal phased array devices to achieve beam scanning originates from microwave phased arrays. By controlling the phase relationship between the light waves emitted from adjacent array elements, a step-shaped blazed grating with a controllable wedge angle can be simulated, so that the incident beam passes through the device and constructively interferes in a specific direction in the far field, thereby producing a beam in that direction. A beam of light with high energy concentration. Therefore, the periodic blazed grating model is used to control the deflection of the beam by changing the number of steps in each cycle, that is, changing the voltage phase difference. This implementation method can change the direction of light wave propagation in real time and accurately by controlling the electric field intensity, and has the advantages of low driving voltage, small mass, and small volume.

According to the blazed grating formula tanθ=λ/T, it can be concluded that the beam polarization angle θ is inversely proportional to the grating period T. Among them, λ represents the wavelength of incident light. Therefore, large angle beam deflection requires the liquid crystal phased array device to produce a smaller phase period. Considering the limitations of LCoS backplane chip design and manufacturing process, the current minimum pixel size is 3.74μm, so the maximum supported beam deflection angle is only about 10°, and it is difficult to further increase this angle. In addition, when a voltage is applied to the liquid crystal phased array, the phase cannot be quickly reset from 2π back to 0, but a falling return zone is generated, and the return zone will affect the beam deflection efficiency to a great extent. As the deflection angle of LCoS increases, the grating period decreases and the return area of the device increases, resulting in a significant reduction in diffraction efficiency and an increase in insertion loss, which will further limit the maximum deflection angle of LCoS.

In summary, although liquid crystal optical phased array devices can achieve high-precision, non-mechanical, and stable beam scanning within a certain range, due to the large pixel size and optical return area, deflection The angle is limited and has higher insertion loss at large angle deflections. Therefore, how to achieve large-angle deflection of LCoS devices and maintain low insertion loss is an urgent problem to be solved.

In view of this, the technical solution of this application proposes a liquid crystal device (for example, an LCOS device) that supports low insertion loss and large angle deflection. By preparing an extremely thin (sub-wavelength level) metasurface structure with beam deflection function on the silicon-based backplane, the pretilt angle can be introduced to flexibly adjust the device beam scanning range. At the same time, the two-level light modulation system can be used to expand the overall performance of the liquid crystal device. Beam deflection capability. In addition, the liquid crystal device disclosed in this application does not rely on the modulation of the liquid crystal layer of traditional LCoS devices, so its diffraction efficiency and device insertion loss are no different from traditional LCoS devices.

In order to facilitate understanding of the embodiments of this application, the following points are explained:

In the embodiments of this application, "at least one" refers to one or more, and "multiple" refers to two or more. "And/or" describes the relationship between associated objects, indicating that there can be three relationships. For example, A and/or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. Among them, A and B can be singular or plural. In the text description of this application, the character "/" generally indicates that the related objects are in an "or" relationship.

In the embodiments of this application, "when..." means that the device will perform corresponding processing under certain objective circumstances. It does not limit the time, and it does not require the device to make judgment actions during implementation, nor does it require means there are other limitations.

It can be understood that in the embodiments shown below, “first”, “second” and various numerical numbers (for example, #1, #2) are only for convenience of description and are not used to limit the present application. Scope of Examples. The sequence numbers of each process below do not mean the order of execution. The execution order of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

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

FIG. 1 is a schematic structural diagram of a liquid crystal device 100 provided by an embodiment of the present application. As shown in FIG. 1 , taking a silicon-based liquid crystal LCoS device as an example, the liquid crystal device 100 includes: a transparent cover 101 , a liquid crystal layer 102 , a silicon-based backplane 107 , a metasurface structure 104 and a cladding layer 103 .

Among them, the transparent cover 101 is located on the liquid crystal layer 102, the metasurface structure 104 and the coating layer 103 are located on the silicon-based backplane 107, the liquid crystal layer 102 is located between the transparent cover 101 and the coating layer 103, and the coating layer 103 Located between the metasurface structure 104 and the liquid crystal layer 102 .

It should be noted that the metasurface structure in the embodiments of the present application can also be called a metasurface structure, and this application does not specifically limit this. 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. Optionally, the silicon-based backplane may be doped with some other metal materials.

It should be understood that the metasurface structure is a micro-nano structure with a lateral sub-wavelength scale, which can modulate the 0 to 2π phase gradient on a thin film structure layer of less than one optical wavelength, thereby achieving control of the phase and polarization of light waves and electromagnetic waves. Flexible and effective control of characteristics such as methods and communication modes. Moreover, the thickness of the metasurface structure is in the subwavelength range, which is more conducive to applications in integrated optics.

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 may be silicon, and the material of the cladding layer 103 may be silicon oxide or silicon nitride.

Specifically, the metasurface structure 104 is used to adjust the deflection angle of the optical signal. The cladding layer 103 serves to flatten the metasurface structure 104 . Among them, flattening refers to filling the surface of the micro-nano structure (metastructure surface structure 104) to make the surface smooth, which is conducive to compatibility with the subsequent packaging process of the liquid crystal layer 102.

For example, the liquid crystal device 100 is a liquid crystal on silicon LCoS device. It should be understood that LCoS technology uses the principle of liquid crystal grating to adjust the light reflection angle of different wavelengths to achieve the purpose of separating light.

Optionally, the liquid crystal device is a liquid crystal display LCD.

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

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

For example, the material of the reflective layer may be aluminum, which is used to improve the reflectivity of the silicon-based backplane. The material of the passivation layer can be dielectric material SiO2 or SiN, which is used to prevent the oxidation of Al metal.

Optionally, the driving circuit 106 is a CMOS chip.

Optionally, the silicon-based backplane 107 also includes an electrode layer #2 and a pixel array. Among them, 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 the pixel array are integrated on the driving circuit 106, and the driving circuit 106. The reflective layer and passivation layer 105 are integrated on the silicon-based backplane 107.

The pixel array may include multiple pixels, and each pixel supports independent adjustment to control the liquid crystal phase in the pixel. The pixel array may be an aluminum Al layer, including, for example, 1952×1088 pixels.

Exemplarily, the modulator of the LCoS device modulates the pixels in the pixel array, and applies the modulated voltage on the pixels to the liquid crystal layer 102 through the electrode layer #2, so that the refractive index of the corresponding pixel liquid crystal changes. By modulating the liquid crystal The refractive index changes the phase of reflected light.

In one possible implementation, the side of the transparent cover 101 close to the liquid crystal layer 102 includes electrode layer #1.

Among them, electrode layer #1 is used to protect the liquid crystal layer, and to transmit optical signals and conduct electricity.

Optionally, electrode layer #1 is an indium tin oxide ITO layer. Among them, the ITO layer has good electrical conductivity and transparency, and can transmit optical signals and conduct electricity.

Exemplarily, electrode layer #2 is included between the liquid crystal layer 102 and the cladding layer 103 . That is to say, the liquid crystal layer 102 includes a guiding material that can fix the alignment direction of liquid crystal molecules under zero voltage conditions. Therefore, there are electrode layers on both upper and lower sides of the liquid crystal layer 102 . For example, electrode layer #1 is the negative electrode, and electrode layer #2 is the positive electrode.

Specifically, when the liquid crystal layer 102 has no voltage, the liquid crystal crystals are arranged in parallel. As the voltage gradually increases and reaches the threshold voltage, the liquid crystal crystal will rotate at a certain angle. Because liquid crystals produce birefringence under the action of an electric field, different electric field strengths will cause the liquid crystal crystal to rotate to varying degrees, thereby changing its refractive index and achieving the purpose of phase modulation of the light beam.

That is to say, the liquid crystal device 100 applies a voltage between the reflective layer 105 and the transparent cover 101 through the driving circuit 106 to regulate the orientation of the liquid crystal molecules of the liquid crystal layer 102 (ie, the rotation angle of the main axis of the liquid crystal molecules), that is, the liquid crystal The molecules are deflected under the action of the liquid crystal driving voltage, thereby achieving the purpose of phase modulation of the light beam. Therefore, the direction of light wave propagation can be changed in real time and accurately by controlling the electric field intensity, and has the advantages of low driving voltage, small mass, and small volume.

In a possible implementation, the metastructure surface structure includes multiple unit cells, each of the multiple unit cells includes multiple micro-nano structures, and the surface areas of the multiple micro-nano structures gradually increase along the same direction.

It should be understood that micro-nano structures are ultra-thin structures with sub-wavelength dimensions. Each micro-nano structure has a specific phase retardation for incident light. The size and spatial arrangement of different micro-nano structures can generate specific phase gradients.

Specifically, the surface area of multiple micro-nano structures gradually increases along the same direction, which can be understood as: the geometric parameters (for example, radius R, side length (eg, length and width), perimeter) of multiple micro-nano structures increase along the same direction. gradually increase.

Exemplarily, FIG. 2 is a schematic structural diagram of the unit cells of the metasurface structure 104 provided by the embodiment of the present application. As shown in Figure 2, the shape of the metasurface structure is cylindrical as an example for explanation.

Specifically, the unit cell of the metastructure surface structure includes multiple micro-nano structures of different geometric sizes. The cylinder diameters of different micro-nano structures gradually increase from R0 to R7, and the corresponding phases gradually increase from 0 to 2π. As shown by the arrow, it can be seen that from left to right, the phase retardation gradually changes due to the different sizes of the micro-nano structures, ultimately achieving the effect of beam deflection.

It should be understood that each micro-nano structure has a specific phase retardation for incident light, so by adjusting the geometric parameters of the micro-nano structure (such as the diameter R of the cylinder), flexible adjustment of the phase retardation of the incident light can be achieved. Arranging micro-nano structures with different phase retardations in space can produce a specific phase gradient in the horizontal direction, ensuring flexible adjustment of the deflection of the incident light propagation direction.

It should be understood that the shapes and geometric dimensions of different micro-nano structures provided above are only schematic illustrations and should not limit the present application.

Optionally, the shape of the micro-nano structure includes at least one of a rectangular shape, a cylindrical shape, or an elliptical cylindrical shape.

Optionally, the material of the micro-nano structure includes at least one of gold, silver, aluminum, silicon, gallium nitride or titanium oxide.

That is to say, the shapes and materials of the micro-nano structures in the same unit cell or in units with different superstructure surface structures may be the same or different, and this application does not specifically limit this. However, from the perspective of CMOS process design, the same element The shapes and materials of multiple micro-nano structures in a cell are usually the same.

For example, when the shape of the micro-nano structure is a rectangle, the corresponding geometric parameter can be length, width or perimeter; when the shape of the micro-nano structure is cylindrical, the corresponding geometric parameter can be R or the perimeter.

In this implementation, the metasurface structure is generally arranged periodically according to the unit cells, that is, the periods of multiple units of the same metasurface structure are usually the same, and the multiple micro-nano structures in each unit cell are The geometric parameters gradually change in the same direction. For example, metasurface structure #1 includes cell #1 and cell #2, then cell #1 and cell #2 respectively include 6 micro-nano structures, and the surface areas of these 6 micro-nano structures are along the inner edge of the cell. increasing in the same direction (for example, from left to right).

In one possible implementation, the number of micro-nano structures in the cells of any two metasurface structures is different.

For example, the unit cell of super surface structure #1 includes 10 micro-nano structures, and the unit cell of super surface structure #2 includes 8 micro-nano structures.

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

In a possible implementation, the sizes of the micro-nano structures in the cells of any two metastructure surface structures are different, and the size of the micro-nano structures is related to the wavelength of the incident light.

It should be understood that the size of the micro-nano structure is related to the wavelength of the incident light. It can be understood that the size variation range of the micro-nano structure is generally λ/4 to λ/2, where λ is the wavelength of the incident light, that is, the size of the micro-nano structure is greater than Or equal to one quarter of the wavelength of the incident light, and less than or equal to one half of the wavelength of the incident light.

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 different ranges of beam deflection, such as -90 to 90°.

Considering that micro-nano structures of different sizes have specific phase delays, different micro-nano structures can produce different phase gradients in different areas on the silicon-based backplane 107. Therefore, the metasurface structure 104 can be used to achieve -90° to 90°. beam deflection angle range.

Since the liquid crystal device itself can use liquid crystal dynamic adjustment to achieve small-angle scanning of the beam, combined with the static pretilt angle A (-90° to 90°) introduced by the metastructure, the scanning range of the liquid crystal device can be flexibly adjusted.

For example, FIG. 3 is a schematic diagram 3 of the beam scanning range adjusted by the liquid crystal device 100 provided by the embodiment of the present application.

As shown in Figure 3, assuming that the scanning angle of the liquid crystal modulation of the liquid crystal layer 102 itself is -B~B, preparing a micro-nano structure (ie, metastructure 104) on the silicon-based backplane 107 can achieve fixed deflection of reflected light. The angle (i.e., pretilt angle) is A (solid arrow). By utilizing the dynamic angle deflection adjustment of the LCoS device from -B° to B°, the beam deflection scanning of the LCoS device from the A-B to A+B angle range can finally be achieved (dashed line arrow).

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

It should be noted that the beam scanning range adjusted by the liquid crystal device provided above is only an illustrative description and should not limit the present application.

In order to expand the beam scanning range of the liquid crystal device, micro-nano structures of different geometric sizes can be prepared in different areas of the silicon-based backplane 107 to adjust the pretilt angle A, thereby achieving different dynamic deflection angle ranges. At the same time, the use of two-level light modulation systems (e.g., LCoS1 and LCoS2) can overall expand the beam deflection capabilities of LCoS devices.

In a possible implementation, the liquid crystal device includes multiple metasurface structures, wherein any two metasurface structures are located in different areas of the silicon-based backplane, and the periodicity of the cells of any two metasurface structures different.

Specifically, according to the blazed grating formula tanθ=λ/T, it can be concluded that the beam deflection angle θ is inversely proportional to the grating period T. Among them, λ represents the wavelength of incident light.

The beam deflection angle θ can be flexibly adjusted by changing the phase gradient. Using the different periods of the cells of the metastructure surface structure, different phase gradients (for example, 0~2π) can be generated, and then different pretilt angles (A) can be introduced to achieve - Beam deflection in 90° to 90° angle range.

For example, metasurface structure #1 includes unit cell #1 and unit cell #2. Unit cell #1 and unit cell #2 each include 10 micro-nano structures, with the size gradually increasing from 1 nm to 10 nm, and the phase gradient is 0. ~2π. Similarly, metasurface structure #2 includes unit cell #3 and unit cell #4. Unit cell #3 and unit cell #4 each include 8 micro-nano structures, with the size gradually increasing from 1 nm to 8 nm, and the phase gradient is 0. ~π. At this time, the periods of the cells of metasurface structure #1 (cell #1) and metasurface structure #2 (cell #3) are different.

For example, FIG. 4 is a schematic structural diagram of the partitions of the silicon-based backplane 107 of the liquid crystal device 100 provided by the embodiment of the present application. As shown in FIG. 4 , the silicon-based backplane 107 of the liquid crystal device 100 (eg, LCoS device) is divided into three columns and three rows, a total of nine areas.

Specifically, the central area of the silicon-based backplane 107 has no metastructure, and the deflection angle scanning from -B to B can be achieved by relying on the liquid crystal drive of the liquid crystal device itself. The three left column areas of the silicon-based backplane 107 are respectively prepared with metastructure surface structures 104, which can produce corresponding pretilt angles A1=-B, A2=-3B, and A3=-5B, thereby realizing the liquid crystal device from -2B to 0, - Beam deflection scanning in the range of 4B～-2B, -6B～-4B. Similarly, three regions on the right side of the silicon-based backplane 107 are respectively prepared with meta-surface structures 104, which can produce corresponding pretilt angles A4=B, A5=3B, and A6=5B, thereby realizing the liquid crystal device from 0 to 2B, 2B to Beam deflection scanning in the range of 4B and 4B~6B.

That is to say, the liquid crystal device 100 is based on the traditional LCoS device structure and integrates the sub-wavelength metasurface structure 104 with beam deflection function onto the silicon-based backplane 107 to achieve pre-tilt in the beam propagation direction. Among them, the specific beam deflection angle A can be flexibly adjusted through different designs of micro-nano structures (for example, by changing the size, material, spatial arrangement, etc. of the micro-nano structures), ultimately achieving beam deflection scanning in the range of A-B to A+B. .

It should be noted that the beam scanning range and spatial arrangement of the liquid crystal device provided above are only illustrative descriptions and should not limit the present application.

In a possible implementation, the liquid crystal device further includes a reflective device.

Wherein, the reflective device is used to irradiate the incident light after completing the first-level light modulation to the second area of the liquid crystal device to perform the second-level light modulation. The first level of light modulation is based on the incident light irradiating the first area of the liquid crystal device, and the second area and the first area are located in different areas of the silicon-based backplane.

For example, the reflective device may be a lens, and one side of the lens has a hollow reflective mirror coating.

By irradiating the incident light twice to two different areas of the silicon-based backplane of the liquid crystal device for 2-level light modulation, the beam deflection capability of the liquid crystal device can be expanded as a whole. For example, the angle range of the first-level light modulation is -B~B, and the angle range of the second-level light modulation is A-B~A+B, where A is the pretilt angle introduced by the metasurface structure.

For example, FIG. 5 is a schematic structural diagram of a two-stage optical modulation system 500 provided by an embodiment of the present application. Taking an LCoS device as an example, as shown in FIG. 5 , the optical modulation system 500 includes an LCoS device (ie, an example of the liquid crystal device 100 ) and a lens. One side of the lens has a mirror coating with a hollow center.

Specifically, the incident light is incident from the center of the lens, passes through the coated mirror in the central hollow part, and is irradiated to the central area of the LCoS for first-level light modulation. By adjusting the liquid crystal in the central area of LCoS, the reflection angle of the light beam can be flexibly adjusted (for example, the adjustment range is -B~B). The coated mirror on one side of the lens is then used to selectively illuminate the beam to other different areas of the LCoS for second-level light modulation to achieve beam scanning in other angle ranges.

It should be understood that the central area where the first level of light modulation is performed does not have the metasurface structure 104, and the other areas where the second level of light modulation is performed have A region has a metasurface structure 104, and each other region may have a different metasurface structure 104, which is not specifically limited in this application. Since the metasurface structures on different areas are different, the introduced pretilt angle A is also different (for example, A1 or A2), so the beam scanning range of the entire LCoS device is also different and has multiple scanning ranges (for example, A1-B ~A1+B or A2-B~A2+B), which can further expand the beam deflection capability of the LCoS device as a whole.

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

It should be understood that the optical modulation system 500 shown in FIG. 5 is only a schematic illustration and should not limit the present application. The optical modulation system 500 may also include other optical path changing devices such as mirrors, spectroscopic gratings, and collimators.

The liquid crystal device 100 disclosed in this application, taking the LCoS device as an example, prepares one or more layers of metasurface structures 104 between the silicon-based backplane 107 and the liquid crystal layer 102, and introduces a beam pretilt angle (A) to achieve alignment. Pretilt of beam propagation direction. Compared with traditional LCoS devices, there is one more degree of freedom to adjust the beam deflection angle, making it possible to flexibly adjust 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 light beam by the metasurface structure 104 and the dynamic deflection and scanning of the light beam by the liquid crystal layer 102 of the traditional LCoS device, the overall beam angle scanning range (A-B～A+B) is broadened. On this basis, metasurface structures 104 with different pretilt angles are prepared in different areas of the silicon-based backplane 107, and then the maximum deflection angle of the liquid crystal device 100 can be greatly increased by using the two-level optical modulation system 500. In addition, the function of realizing large-angle beam scanning of the liquid crystal device 100 disclosed in this application comes from the introduction of the metasurface structure 104 and does not rely on the modulation of the device liquid crystal layer 102. Its diffraction efficiency and insertion loss are no different from traditional devices. Therefore, no additional insertion loss is introduced, and it is always maintained at a low value. That is to say, the scanning angle range of the device can be greatly increased while maintaining low insertion loss.

It should be understood that the size and position of the transparent cover 101, liquid crystal layer 102, cladding layer 103, metasurface structure 104, reflective layer/passivation layer 105, drive circuit 106 and silicon-based backplane 107 shown in Figure 1 The specific forms are schematic and should not constitute any limitation on this application.

Based on the liquid crystal device shown in FIG. 1 (for example, the new LCoS device 100), FIG. 6 is a schematic flowchart of a liquid crystal device modulation method 600 provided by an embodiment of the present application. As shown in Figure 6, it specifically includes the following two steps.

S610: The incident light is irradiated to the first area of the liquid crystal device to perform first-level light modulation.

Among them, the liquid crystal device includes a silicon-based backplane, a liquid crystal layer, a transparent cover, a metasurface structure, and a cladding layer. The liquid crystal layer is located between the transparent cover and the cladding layer. The cladding layer is located between the metasurface structure and the liquid crystal layer. , the metasurface structure is located between the cladding layer and the silicon-based backplane, and the metasurface structure in the second region is different from that in the first region.

In other words, any two metasurface structures are located in different areas of the silicon-based backplane. It should be understood that the first region and the second region can be regarded as different regions on the silicon-based backplane. For example, see the schematic structural diagram of the partitions of the silicon-based backplane shown in Figure 4. The superstructures on the first region and the second region The difference in the metasurface structure can be understood as the different sizes, materials, shapes, etc. of the micro-nano structures in the cells of the metasurface structure in the two regions, as well as the different periods of the cells of the metasurface structure. In short, a sub-wavelength metasurface structure with beam deflection function is integrated into a silicon-based backplane to generate a pretilt angle A to achieve pretilt in the beam propagation direction. Among them, the specific beam deflection angle A can be flexibly adjusted through different designs of micro-nano structures (for example, by changing the size, material, spatial arrangement, etc. of the micro-nano structures), ultimately achieving beam deflection scanning across a wide range of angles.

Exemplarily, the metasurface structure includes a plurality of unit cells, each of the plurality of unit cells includes a plurality of micro-nano structures, and the surface areas of the multiple micro-nano structures gradually increase along the same direction.

Optionally, the liquid crystal device includes multiple metasurface structures, wherein any two metasurface structures are located in different areas of the silicon-based backplane, and the periods of the cells of any two metasurface structures are different.

Optionally, the number of micro-nano structures in the unit cells of any two superstructure surface structures is different.

Optionally, the sizes of the micro-nano structures in the cells of any two metasurface structures are different, wherein the size of the micro-nano structures is greater than or equal to one-quarter of the wavelength of the incident light, and is less than or equal to the wavelength of the incident light. Half.

S620, the modulated incident light is irradiated to the second area of the liquid crystal device through the reflective device to perform second-level light modulation.

For example, the reflective device may be a lens, and one side of the lens has a hollow reflective mirror coating. It should be understood that a reflective device is a device with a reflective function, as long as it can reflect the first-level modulated light to the second area for second-level light modulation, which is not specifically limited in this application.

It should be understood that the description of the method embodiments corresponds to the description of the device embodiments. Therefore, the parts not described in detail can be referred to the previous device embodiments.

Based on the above solution, the incident light is irradiated twice to two different areas of the silicon-based backplane of the liquid crystal device for 2-level light modulation, which can overall expand the beam deflection capability of the liquid crystal device. For example, the angle range of the first-level light modulation is -B~B, and the angle range of the second-level light modulation is A-B~A+B, where A is the pretilt angle introduced by the metasurface structure.

In summary, based on the traditional LCOS device, a layer of sub-wavelength metasurface structure with beam deflection function is integrated into the silicon-based backplane of the liquid crystal device to achieve pre-tilt of the beam propagation direction. The deflection angle can be flexibly adjusted through the design of the micro-nano structure (for example, changing the size, size, material, shape, etc. of the micro-nano structure). At the same time, LCoS is used to drive the liquid crystal to achieve dynamic beam scanning near the pretilt angle introduced by the superstructure. On this basis, metasurface structures with different pretilt angles are prepared in different areas of the silicon-based backplane, and a two-stage dimming system is used to greatly 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.

As a reflective spatial light modulator based on silicon backplane, silicon-based liquid crystal LCoS combines liquid crystal technology with CMOS technology, with optical phase modulation as the core. It is widely used in applications including but not limited to optical communications, displays, car lights, and lasers. Radar, optical switching, driverless driving, laser projection, laser display, laser processing and other fields. Because LCoS has good passband tuning flexibility, optical network hardware compatibility and beam deflection stability, it is currently more and more commonly used in wavelength selective switches WSS.

Exemplarily, FIG. 7 is a schematic structural diagram of a WSS 700 provided by an embodiment of the present application, that is, an application scenario for driving modulation of a liquid crystal device 100 (for example, an LCoS device).

As shown in Figure 7, the N×N WSS includes N input ports 701, LCoS1 702, N output ports 703, LCoS2 705, and lenses 704. This WSS can realize any pairing of all-optical connections between input ports and output ports. In other words, an optical signal of any wavelength among the N input ports can be output from any one of the N output ports after modulation by driving.

It should be understood that the WSS provided by the embodiment of the present application performs secondary modulation on the phase of the optical signal through LCOS1 702 and LCoS2 705, thereby changing the transmission direction of the optical signal.

For example, the optical signal can be input from at least one input port 1 among the N input ports 701. After being modulated and selected by LCOS1 702, it is irradiated to the lens 704, and then reflected by the lens 704 and irradiated to LCOS2 705 for modulation. Finally, the modulated signal is The final optical signal is output from at least one output port N among the N output ports 703, thereby completing a change in the transmission direction of the optical signal, such as completing the exchange, uploading or downloading of optical signals.

Specifically, metasurface structures 104 of different designs are prepared in different areas on the silicon-based backplanes of the LCOS1 702 and LCOS2 705. The specific sizes, quantities, materials, etc. can be found in the description of the above-mentioned liquid crystal device 100. For simplicity, No further details will be given here.

Alternatively, the input/output ports may be composed of optical fibers, and the input/output ports may form an input/output optical fiber array.

It should be understood that the number of output ports and the number of output ports in FIG. 7 are equal is only an exemplary illustration. In specific implementation, the number of input ports and output ports may be equal or unequal, and this application does not specifically limit this.

It should also be understood that the structural diagram of the WSS shown in Figure 7 is only an exemplary illustration, and the present application is not limited thereto. For example, the WSS may also include optical path changing devices such as lenses, mirrors, spectroscopic gratings, and collimators.

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. The above-mentioned specific implementations can be considered as the optimal implementations of this application, but do not limit the implementation of this application. range of examples.

Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each specific application, but such implementations should not be considered beyond the scope of this application.

Those skilled in the art can clearly understand that for the convenience and simplicity of description, 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 described again here.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or can be integrated into another system, or some features can be ignored, or not implemented. On the other hand, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection of the devices or units may be in electrical, mechanical or other forms.

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

In addition, each functional unit in each embodiment of the present application can be integrated into one processing unit, each unit can exist physically alone, or two or more units can be integrated into one unit.

If the functions are implemented in the form of 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 the present application is essentially or the part that contributes to the existing technology or the part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk and other media that can store program code. .

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (20)

1. A liquid crystal device, characterized by comprising: 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 and the coating layer. The coating layer is located between the metasurface structure and the liquid crystal layer. The metasurface structure is located on the coating layer. layer and the silicon-based backplane.
2. The liquid crystal device according to claim 1, characterized in that the liquid crystal device is a liquid crystal on silicon LCoS device.
3. The liquid crystal device according to claim 1 or 2, characterized in that the side of the transparent cover close to the liquid crystal layer includes an electrode layer.
4. The liquid crystal device according to claim 3, wherein the electrode layer is an indium tin oxide (ITO) layer.
5. The liquid crystal device according to any one of claims 1 to 4, wherein the silicon-based backplane includes a driving circuit, a reflective layer and a passivation layer, and the reflective layer and the passivation layer are located on the superstructure. between the surface structure and the drive circuit.
6. The liquid crystal device according to any one of claims 1 to 5, wherein the metasurface structure includes a plurality of unit cells, and each unit cell in the plurality of unit cells includes a plurality of micro-nano structures. , the surface areas of the multiple micro-nano structures gradually increase along the same direction.
7. The liquid crystal device according to any one of claims 1 to 6, characterized in that the liquid crystal device includes a plurality of the metasurface structures, wherein any two of the metasurface structures are located on the silicon base. The areas of the backplate are different, and the periods of any two cells of the metastructure surface structure are different.
8. The liquid crystal device according to claim 7, characterized in that the number of micro-nano structures in any two cells of the metastructure surface structure is different.
9. The liquid crystal device according to claim 7 or 8, characterized in that the sizes of the micro-nano structures in any two cells of the metastructure surface structure are different, wherein the size of the micro-nano structures is greater than or equal to the incident light. One quarter of the wavelength of the light, and less than or equal to one half of the wavelength of the incident light.
10. The liquid crystal device according to any one of claims 7 to 9, characterized in that the liquid crystal device further includes a reflective device, wherein:

    The reflective device is used to irradiate the incident light that completes the first-level light modulation to the second area of the liquid crystal device to perform the second-level light modulation,

    Wherein, the first-level light modulation is performed based on the incident light irradiating the first area of the liquid crystal device, and the second area and the first area are located in different areas of the silicon-based backplane.
11. The liquid crystal device according to any one of claims 6 to 10, wherein the shape of the micro-nano structure includes at least one of a rectangular shape, a cylindrical shape, or an elliptical cylindrical shape.
12. The liquid crystal device according to any one of claims 6 to 11, wherein the material of the micro-nano structure includes at least one of gold, silver, aluminum, silicon, gallium nitride or titanium oxide.
13. An optical modulation device, characterized by including:

    The liquid crystal device according to any one of claims 1 to 12; and

    A reflective device for irradiating the incident light that completes the first-level light modulation to the second area of the liquid crystal device to perform the second-level light modulation. The first-level light modulation is based on the incident light irradiating to the second area of the liquid crystal device. The method is performed on the first region of the liquid crystal device, and the metasurface structure on the second region is different from that on the first region.
14. The optical modulation device according to claim 13, characterized in that the optical modulation device is applied to wavelength Select switch WSS.
15. An optical modulation system, characterized by comprising: the optical modulation device according to claim 13 or 14.
16. A liquid crystal device modulation method, characterized by including:

    Incident light is irradiated to the first area of the liquid crystal device to perform first-level light modulation;

    The modulated incident light is irradiated to the second area of the liquid crystal device through the reflective device to perform second-level light modulation;

    Wherein, 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, 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 second region and the first region The metasurface structures are different.
17. The method of claim 16, wherein the metasurface structure includes a plurality of unit cells, each of the plurality of unit cells includes a plurality of micro-nano structures, and the plurality of micro-nano structures The surface area of the structure gradually increases in the same direction.
18. The method according to claim 16 or 17, characterized in that the liquid crystal device includes a plurality of the metasurface structures, wherein any two of the metasurface structures are located in different areas of the silicon-based backplane. , and the periods of any two cells of the metasurface structure are different.
19. The method according to claim 18, characterized in that the number of micro-nano structures in any two cells of the superstructure surface structure is different.
20. The method according to claim 18 or 19, characterized in that the sizes of the micro-nano structures in the cells of any two of the metastructure surface structures are different, wherein the size of the micro-nano structures is greater than or equal to the One quarter of the wavelength of the incident light, and less than or equal to one half of the wavelength of the incident light.