Liquid crystal on silicon (LCOS) device and wavelength selective switch (WSS)

Abstract

The present application provides a silicon-based liquid crystal (LCOS) device and a wavelength selective switch (WSS). In the present application, the LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of a received optical signal with a first polarization direction into a second direction, and convert the polarization direction of a received optical signal with a second polarization direction into the first direction. The liquid crystal box can adjust the phase of the optical signal with a first polarization direction in the optical signal output by the first transparent electrode and the metasurface according to the target voltage. It can be seen that the LCOS device can perform polarization diversity processing and conversion processing on the optical signal through the metasurface. The implementation method of the metasurface is simple, occupies a small volume, reduces the complexity of the device, reduces the construction cost of the device, and is more conducive to the promotion of technology.

Description

Technical Field

[0001] The present application relates to the field of communications, and in particular to a liquid crystal on silicon (LCOS) device and a wavelength selective switch (WSS). Background Art

[0002] LCOS is a miniaturized reflective active-matrix liquid crystal display (LCD), also known as a "microdisplay." LCOS devices are also known as spatial light modulators. In an LCOS device, a liquid crystal layer is layered on top of a silicon substrate, enabling the modulation of light fields. LCOS devices offer numerous advantages, including flexible light field manipulation, rewritable and rewritable features, and high resolution. Consequently, they have found widespread application in a wide range of fields.

[0003] In conventional technology, the liquid crystal layer in LCOS devices is primarily made of nematic liquid crystals. Nematic liquid crystals are primarily composed of non-polar, rod-shaped liquid crystal molecules with uniaxial crystal properties. When implementing light field phase modulation in conventional LCOS devices, the plane in which the LCOS device resides is defined as the XY plane, with the normal to the XY plane defined as the Z direction. In the XY plane, the orientation of the long axis of the liquid crystal molecules in the absence of voltage is defined as the X direction, and the direction perpendicular to both the X and Z directions is defined as the Y direction. Applying a voltage to a conventional LCOS device can cause the orientation of the liquid crystal molecules to rotate from the X direction to the Z direction. Different voltages result in different angles of rotation from the X direction to the Z direction. Therefore, the orientation of the liquid crystal molecules under different voltages is different within the XZ plane. In this case, incident light polarized in the X direction corresponds to extraordinary light (e-light), whose refractive index changes with the orientation of the liquid crystal molecules. Therefore, while maintaining the thickness of the liquid crystal layer, adjusting the voltage applied to the LCOS device can achieve phase modulation of incident light polarized in the X direction. The incident light polarized in the Y direction corresponds to ordinary light (or o-light for short), whose refractive index does not change with the orientation of the liquid crystal molecules, and phase modulation cannot be achieved.

[0004] In traditional LCOS devices, when incident light has polarization components in both the X and Y directions, a peripheral optical path consisting of multiple components is typically required to perform polarization diversity processing and conversion on the optical signal. This peripheral optical path is complex and occupies a large volume, increasing the complexity and cost of the device. Summary of the Invention

[0005] This application provides a liquid crystal on silicon (LCOS) device and a wavelength selective switch (WSS). The WSS includes an LCOS device that can perform polarization diversity processing and conversion on optical signals via a metasurface. The metasurface is simple to implement and occupies a small volume, reducing device complexity and construction costs, and facilitating technology dissemination.

[0006] In a first aspect, the present application provides a liquid crystal on silicon (LCOS) device, characterized in that the LCOS device includes a first transparent electrode, a liquid crystal cell, a metasurface, an electrode layer, and a driving circuit, wherein the thickness of the metasurface includes a subwavelength order; the first transparent electrode is used to receive an incident light signal, wherein the polarization direction of the incident light signal includes a first direction and a second direction, wherein the first direction is used to represent a direction parallel to a target intersection line, wherein the target intersection line represents an intersection line between a pixel array plane and a liquid crystal rotation plane, and the second direction is used to represent a direction perpendicular to the liquid crystal rotation plane; the metasurface is used to convert the polarization direction of a received light signal having a polarization direction in the first direction into the second direction, and convert the polarization direction of a received light signal having a polarization direction in the second direction into the first direction; the driving circuit is used to configure a target voltage, wherein the target voltage represents a voltage between the first transparent electrode and the electrode layer; and the liquid crystal cell is used to adjust the phase of the light signal having a polarization direction in the first direction, among the light signals output by the first transparent electrode and the metasurface, according to the target voltage.

[0007] In the present application, the LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of a received optical signal with a first polarization direction into a second direction, and convert the polarization direction of a received optical signal with a second polarization direction into the first direction. The liquid crystal cell can adjust the phase of the optical signal with a first polarization direction in the optical signal output by the first transparent electrode and the metasurface according to the target voltage. Thus, it can be seen that the LCOS device can perform polarization diversity processing and conversion processing on the optical signal through the metasurface. The implementation method of the metasurface is simple, the volume is small, the complexity of the device is reduced, the construction cost of the device is reduced, and it is more conducive to the promotion of technology.

[0008] In a possible implementation of the first aspect, the orientations or sizes of the basic units in the metasurface are different to suppress crosstalk signals, where the crosstalk signals include optical signals whose polarization states are not converted after passing through the metasurface.

[0009] In this possible implementation, to address the crosstalk problem caused by residual light with unconverted polarization, a joint phase modulation scheme using a metasurface and a liquid crystal cell can be used for improvement. The basic idea behind this possible implementation is to simultaneously polarize the incident light while introducing different phases to the incident light through the orientation or size arrangement of the basic units in the metasurface, giving the optical signal a specific perturbed phase distribution. Then, through liquid crystal dynamic phase modulation, a compensation phase distribution complementary to the perturbed phase distribution is introduced based on the beam deflection phase. This allows the perturbed phase and compensation phase generated by the joint phase modulation between the metasurface and the liquid crystal cell for the normally polarized light to cancel each other out. Therefore, the normally polarized light signal can be deflected and coupled to the output port while maintaining its original spot shape. However, for crosstalk light from unconverted and other diffraction orders, the perturbed phase and compensation phase cannot completely cancel each other out due to the different phase modulation amounts experienced. Consequently, the spot becomes diffuse and cannot be efficiently coupled into the output port, effectively suppressing crosstalk.

[0010] In a possible implementation of the first aspect, the metasurface includes a first region and a second region, the angle between the orientation of the basic units in the first region and the pixel array plane is different from the angle between the orientation of the basic units in the second region and the pixel array plane, and the liquid crystal box includes a third region and a fourth region; the first region is used to add a first phase to the optical signal having the polarization direction converted to the first direction and the second direction; The second region is used to add a first phase to the optical signal whose polarization direction is converted into the first direction and the second direction. The first phase and the second phase The third region is used to add a third phase to the optical signal whose polarization direction is the first direction output by the first transparent electrode and the first region. k is an integer; the fourth region is used to add a fourth phase to the optical signal whose polarization direction is the first direction output by the first transparent electrode and the second region k is an integer.

[0011] In this possible implementation, the orientation of the basic units in the metasurface represents the angle between the basic units in the metasurface and the pixel array plane. If the orientations of the basic units in the first and second regions are different, and the polarization state of signal A remains unchanged after passing through the first region, and the polarization state of signal B remains unchanged after passing through the second region, the perturbed phase and compensated phase obtained by the unpolarized crosstalk signal A and the crosstalk signal B cannot be completely offset. Furthermore, due to the different orientations of the basic units in the first and second regions, the phase modulation amounts obtained by the crosstalk signal A and the crosstalk signal B are different, resulting in a diffuse light spot and thus inefficient coupling to the port output, thereby achieving crosstalk signal suppression. In this possible implementation, the basic units in the metasurface are of uniform size, making the design and processing of the metasurface easier to implement, thereby reducing the processing cost of the LCOS device.

[0012] In a possible implementation of the first aspect, the angle between the orientation of the basic units in the first area and the pixel array plane is 45 degrees, and the angle between the orientation of the basic units in the second area and the pixel array plane is 135 degrees.

[0013] In this possible implementation, the angle between the orientation of the basic unit in the first area and the pixel array plane is 45 degrees, and the angle between the orientation of the basic unit in the second area and the pixel array plane is 135 degrees. This can introduce phase modulation of 0 and π respectively while achieving polarization conversion. This possible implementation improves the LCOS device's suppression effect on crosstalk signals.

[0014] In a possible implementation of the first aspect, the metasurface includes a first region and a second region, the size of the basic unit in the first region is different from the size of the basic unit in the second region, and the liquid crystal cell includes a third region and a fourth region; the first region is used to add a first phase to the received optical signal with the polarization direction of the first direction and the second direction. The second region is used to add a second phase to the received optical signal with the polarization direction of the first direction and the second direction. The first phase and the second phase The third region is used to add a third phase to the optical signal whose polarization direction is the first direction output by the first transparent electrode and the first region. k is an integer; the fourth region is used to add a fourth phase to the optical signal whose polarization direction is the first direction output by the first transparent electrode and the second region k is an integer.

[0015] In this possible implementation, if the sizes of the basic units in the first area and the second area are different, and the polarization state of signal A does not change after passing through the first area, and the polarization state of signal B does not change after passing through the second area, the perturbation phase and compensation phase obtained by the unpolarized crosstalk optical signal A and the crosstalk optical signal B cannot be completely offset. Since the sizes of the basic units in the first area and the second area are different, the phase modulation amounts obtained by the crosstalk optical signal A and the crosstalk optical signal B are different, resulting in a diffuse light spot, which cannot be efficiently coupled to the port output, thereby achieving the suppression of the crosstalk signal. In this possible implementation, different perturbation phases can be obtained by adjusting the size of the basic unit, thereby improving the degree of freedom of the LCOS device in setting the perturbation phase.

[0016] In a possible implementation of the first aspect, the electrode layer includes a metal electrode; the first surface of the liquid crystal box is covered with the first transparent electrode, and the second surface of the liquid crystal box is covered with the first surface of the metasurface; the second surface of the metasurface is covered with the first surface of the metal electrode; the second surface of the metal electrode is covered with the driving circuit; and the metal electrode is used to reflect the received light signal.

[0017] In this possible implementation, a possible structure of an LCOS device is provided. In this possible implementation, the metasurface can be directly processed on a traditional LCOS backplane without changing the original backplane structure. The processing is more convenient and saves processing costs.

[0018] In a possible implementation of the first aspect, the electrode layer includes a second transparent electrode and a metal plate; the first surface of the liquid crystal box is covered with the first transparent electrode, and the second surface of the liquid crystal box is covered with the first surface of the second transparent electrode; the second surface of the second transparent electrode is covered with the first surface of the metasurface; the second surface of the metasurface is covered with the first surface of the metal plate; the second surface of the metal plate is covered with the driving circuit; and the metal plate is used to reflect the received light signal.

[0019] In this possible implementation, the metasurface is arranged outside the first transparent electrode and the second transparent electrode, thereby avoiding the structural voltage division generated by the metasurface and reducing the driving voltage of the LCOS device.

[0020] In a possible implementation of the first aspect, the electrode layer includes a second transparent electrode; the first surface of the liquid crystal box is covered with the first transparent electrode, and the second surface of the liquid crystal box is covered with the first surface of the second transparent electrode; the second surface of the second transparent electrode is covered with the first surface of the metasurface; the second surface of the metasurface is covered with the driving circuit; and the metasurface is further used to reflect a received light signal.

[0021] In this possible implementation, the metasurface is arranged outside the first transparent electrode and the second transparent electrode, thereby avoiding the structural voltage division generated by the metasurface, reducing the driving voltage of the LCOS device, and saving energy.

[0022] In a possible implementation manner of the first aspect, a material of the basic unit includes gold, silver, aluminum, platinum, chromium, silicon, silicon nitride, titanium dioxide, or aluminum oxide.

[0023] In this possible implementation, if the basic unit is made of metal, the thickness of the metasurface can be reduced, thereby reducing the structural partial pressure of the metasurface and further reducing the driving voltage of the LCOS device. If the basic unit is made of non-metallic material, the loss of optical signals passing through the metasurface can be reduced.

[0024] In a possible implementation manner of the first aspect, the basic unit is in the shape of a polygonal column or an elliptical column.

[0025] In this possible implementation, two possible implementations of basic units are provided, which improves the feasibility of the solution.

[0026] In a possible implementation of the first aspect, the metasurface further includes a planarization material, and the planarization material includes silicon dioxide, aluminum oxide, silicon nitride, or silicon.

[0027] This possible implementation method provides a possible implementation method for planarizing materials, thereby improving the feasibility of the solution.

[0028] In a possible implementation manner of the first aspect, the LCOS device further includes a passivation layer.

[0029] In this possible implementation, if the electrodes in the electrode layer are metal electrodes, the passivation layer can protect the electrode activity and delay the electrode deactivation process. If the electrodes in the electrode layer are non-metallic electrodes, the passivation layer can further flatten the surface of the non-metallic electrodes.

[0030] A second aspect of the present application provides a wavelength selective switch WSS, which includes an LCOS device as described in the first aspect or any possible implementation of the first aspect.

[0031] The WSS provided in the present application includes an LCOS device. The LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of a received optical signal with a first polarization direction into a second direction, and convert the polarization direction of a received optical signal with a second polarization direction into the first direction. The liquid crystal box can adjust the phase of the optical signal with a first polarization direction in the optical signal output by the first transparent electrode and the metasurface according to the target voltage. It can be seen that the LCOS device can perform polarization diversity processing and conversion processing on the optical signal through the metasurface. The implementation method of the metasurface is simple, and it occupies a small volume inside the WSS, which reduces the complexity of the equipment and the construction cost of the WSS, making the WSS more conducive to technology promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of a WSS provided in this application;

[0033] Figure 2 A schematic structural diagram of an LCOS provided in this application;

[0034] Figure 3 A schematic structural diagram of a liquid crystal cell provided in this application;

[0035] Figure 4 A schematic diagram of an application of an LCOS device provided in this application;

[0036] Figure 5 A polarization conversion efficiency diagram of a metasurface provided in this application;

[0037] Figure 6 A schematic diagram of a crosstalk signal provided in this application;

[0038] Figure 7 A schematic structural diagram of a metasurface provided in this application;

[0039] Figure 8 This is a diagram showing the suppression effect of a crosstalk signal provided by this application;

[0040] Figure 9 Another schematic diagram of the structure of a metasurface provided in this application;

[0041] Figure 10 This is another crosstalk signal suppression effect diagram provided by this application;

[0042] Figure 11 A schematic structural diagram of another LCOS device provided in this application;

[0043] Figure 12 A schematic structural diagram of another LCOS device provided in this application;

[0044] Figure 13 This is a schematic structural diagram of another LCOS device provided in this application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the following describes the embodiments of this application in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this application, rather than all the embodiments. It is known to those skilled in the art that with the emergence of new application scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0046] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules clearly listed, but may include other steps or modules that are not clearly listed or that are inherent to these processes, methods, products or devices. The naming or numbering of steps in this application does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The process steps that have been named or numbered can be changed in the execution order according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved.

[0047] Liquid Crystal on Silicon (LCOS) is a miniaturized reflective active-matrix liquid crystal display (LCD) device, also known as a "microdisplay." LCOS devices are also known as spatial light modulators. In LCOS devices, a liquid crystal layer is placed on top of a silicon substrate, enabling the modulation of light fields. LCOS devices offer numerous advantages, including flexible light field manipulation, rewritable and rewritable technology, and high resolution. Consequently, they have found widespread application in numerous fields.

[0048] In conventional technology, the liquid crystal layer in LCOS devices is primarily made of nematic liquid crystals. Nematic liquid crystals are primarily composed of non-polar, rod-shaped liquid crystal molecules and exhibit uniaxial crystal properties. When implementing light field phase modulation in conventional LCOS devices, the plane in which the LCOS device resides is defined as the XY plane, with the normal to the XY plane defined as the Z direction. In the XY plane, the orientation of the long axis of the liquid crystal molecules in the absence of voltage is defined as the X direction, and the direction perpendicular to both the X and Z directions is defined as the Y direction. Applying a voltage to a conventional LCOS device can rotate the orientation of the liquid crystal molecules from the X direction to the Z direction. Different voltage levels result in different angles of rotation from the X direction to the Z direction. Therefore, the orientation of the liquid crystal molecules in the XZ plane varies under different voltages. In this case, incident light polarized in the X direction corresponds to extraordinary light, and its refractive index changes with the orientation of the liquid crystal molecules. Therefore, while maintaining the thickness of the liquid crystal layer, adjusting the voltage applied to the LCOS device can achieve phase modulation of incident light polarized in the X direction. Incident light polarized in the Y direction corresponds to ordinary light, whose refractive index does not change with the orientation of the liquid crystal molecules, and phase modulation cannot be achieved.

[0049] In traditional LCOS devices, when incident light has polarization components in both the X and Y directions, a peripheral optical path consisting of multiple components is typically required to perform polarization diversity processing and conversion on the optical signal. This peripheral optical path is complex and occupies a large volume, increasing the complexity and cost of the device.

[0050] In response to the above-mentioned problems existing in existing LCOS devices, the present application provides an LCOS device and WSS. The implementation method of the metasurface in the LCOS device is simple, occupies a small volume, reduces the complexity of the device, reduces the construction cost of the device, and is more conducive to the promotion of technology.

[0051] The LCOS device provided in this application and the WSS including the LCOS device will be introduced in detail below in conjunction with the drawings in this application. First, the WSS provided in this application will be introduced.

[0052] Figure 1 A structural diagram of a WSS provided in this application.

[0053] See also Figure 1 In this application, the device for routing optical signals in a reconfigurable optical add / drop multiplexer (ROADM) is a WSS. Figure 1 The WSS shown in FIG includes the LCOS provided by this application. Figure 1As shown, the WSS includes input and output components, dispersion components, spot transformation components and LCOS.

[0054] In this application, the structural diagram of the WSS including LCOS is as follows Figure 1 As shown. After the input and output components receive the combined signal, the dispersion component spatially separates the combined signal light emitted from the input port according to different wavelengths. The spot transformation component projects the separated optical signals to different areas within the LCOS device. The LCOS device deflects the optical signal by phase modulating the different wavelengths of incident light. The deflected optical signal is then transmitted to different output ports through the spot transformation component and the dispersion component, thereby selectively routing optical signals of different wavelengths to the same or different output ports.

[0055] It can be understood that, optionally, the LCOS device provided in the present application can be applied to WSS, the LCOS device provided in the present application can also be applied to holographic display equipment, the LCOS device can also be applied to lidar devices, and the LCOS device provided in the present application can also be used in other devices, which are not specifically limited here.

[0056] The WSS provided in the present application includes an LCOS device. The LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of a received optical signal with a first polarization direction into a second direction, and convert the polarization direction of a received optical signal with a second polarization direction into the first direction. The liquid crystal box can adjust the phase of the optical signal with a first polarization direction in the optical signal output by the first transparent electrode and the metasurface according to the target voltage. It can be seen that the LCOS device can perform polarization diversity processing and conversion processing on the optical signal through the metasurface. The implementation method of the metasurface is simple, and it occupies a small volume inside the WSS, which reduces the complexity of the equipment and the construction cost of the WSS, making the WSS more conducive to technology promotion.

[0057] The above example introduces the WSS provided by the present application. The following will introduce the LCOS device provided by the present application in detail based on the WSS introduced above and in combination with the accompanying drawings.

[0058] Figure 2 A structural diagram of an LCOS provided in this application.

[0059] See also Figure 2 In the present application, the LCOS device 201 includes a first transparent electrode 301, a liquid crystal box 302, a metasurface 303, an electrode layer 304 and a driving circuit 305, wherein the thickness of the metasurface includes a wavelength level or a sub-wavelength level.

[0060] The functions of each component in the LCOS device are described in detail below.

[0061] In the present application, the first transparent electrode 301 can receive an incident light signal, which can include light signals of various polarization directions. The polarization directions of the incident light signal include a first direction and a second direction. The first direction is used to indicate a direction parallel to a target intersection line, which indicates the intersection line between the pixel array plane and the liquid crystal rotation plane. The second direction is used to indicate a direction perpendicular to the liquid crystal rotation plane.

[0062] In the present application, the metasurface 303 can convert the polarization direction of a received optical signal with a first polarization direction into a second polarization direction, and convert the polarization direction of a received optical signal with a second polarization direction into the first polarization direction.

[0063] In the present application, the driving circuit 305 may be configured with a target voltage, where the target voltage is used to represent the voltage between the first transparent electrode 301 and the electrode layer 304 .

[0064] In the present application, the liquid crystal cell 302 can adjust the phase of the optical signal with the polarization direction being the first direction among the optical signals output by the first transparent electrode and the metasurface according to the target voltage.

[0065] First, a specific example is used to illustrate the first direction and the second direction included in the polarization direction of the incident light signal received by the first transparent electrode in the present application.

[0066] Figure 3 This is a structural schematic diagram of a liquid crystal box provided in this application.

[0067] For example, Figure 3 As shown, the liquid crystal cell in current mainstream LCOS devices primarily contains nematic liquid crystals, which are composed of non-polar, rod-shaped liquid crystal molecules and exhibit uniaxial crystal properties. For ease of description, the plane in which the pixels in the liquid crystal cell reside is defined as the pixel array plane, or the XOY plane in the figure. The normal to the XOY plane is defined as the Z direction, corresponding to the direction of applied electric field. The orientation of the long axis of the liquid crystal molecules in the absence of voltage is defined as the X direction, or the first direction, and the direction orthogonal to both the X and Z directions is defined as the Y direction, or the second direction. Applying a voltage can rotate the orientation of the liquid crystal molecules from the X direction to the Z direction, and the XOZ plane is defined as the liquid crystal rotation plane. Different voltages result in different birefringence depending on the orientation of the liquid crystal molecules along the XOZ plane. In this case, incident light polarized in the X direction corresponds to extraordinary light, whose refractive index changes with the orientation of the liquid crystal molecules. Therefore, different voltages can achieve different phase modulations while maintaining the same liquid crystal thickness. Incident light polarized in the Y direction corresponds to ordinary light, whose refractive index does not change with the orientation of the liquid crystal molecules, and thus, no phase modulation can be achieved.

[0068] In combination with the above examples, the working process of the LCOS provided in this application is introduced with a specific example.

[0069] Figure 4 This is a schematic diagram of an application of an LCOS device provided in this application.

[0070] See also Figure 4 In the present application, after the light signal A with polarization direction of X direction (first direction) passes through the first transparent electrode, it will enter the liquid crystal box for the first time. The liquid crystal molecules in the liquid crystal box are subjected to the voltage between the first transparent electrode and the electrode layer to produce orientation changes. Since the X direction is parallel to the long axis orientation of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the light signal A polarized in the X direction, and apply a phase θ to the signal A. Subsequently, the signal A enters the metasurface, which can perform polarization conversion on the signal A. After the polarization conversion, the polarization state of the signal A rotates 90° and becomes a light signal polarized in the Y direction (second direction). The light signal A polarized in the Y direction passes through the liquid crystal box twice after reflection. Since the Y direction is perpendicular to the long axis orientation of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the light signal A polarized in the Y direction, such as Figure 4 It can be seen from this that the LCOS device can perform phase modulation on the optical signal A in the X polarization direction.

[0071] In the present application, light signal A with polarization direction in the Y direction (second direction) enters the liquid crystal box for the first time after passing through the first transparent electrode. The liquid crystal molecules in the liquid crystal box undergo orientation changes due to the voltage between the first transparent electrode and the electrode layer. Since the Y direction is perpendicular to the long axis orientation of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of light signal A polarized in the Y direction. Subsequently, signal A enters the metasurface, which can perform polarization conversion on signal A. After polarization conversion, the polarization state of signal A rotates 90° and becomes a light signal polarized in the X direction (first direction). Light signal A polarized in the X direction passes through the liquid crystal box twice after reflection. Since the X direction is parallel to the long axis orientation of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of light signal A polarized in the X direction, such as Figure 4 , a phase θ is applied to signal A. Thus, the LCOS device can perform phase modulation on optical signal A in the Y polarization direction.

[0072] In summary, regardless of whether the incident light is X-polarized or Y-polarized, the same liquid crystal molecular phase modulation is achieved throughout the entire process from its entry into the LCOS device to its final exit. Light signals with any other polarization state in the incident light can always be decomposed into a combination of a light component with an X polarization state and a light component with a Y polarization state, similarly achieving only a single liquid crystal molecular phase modulation. Therefore, the LCOS device exhibits polarization-independent phase response characteristics.

[0073] In the present application, if the LCOS device is located between the first transparent electrode and the electrode layer, the thickness of the metasurface included in the LCOS device provided herein can be significantly less than the thickness of the liquid crystal cell. Optionally, the thickness of the metasurface can be slightly greater than the wavelength of the signal light received during operation. For example, the thickness of the metasurface can be 2.9 times the wavelength of the signal light, or 1.5 times the wavelength of the signal light, or other values, which are not specifically limited herein. The thickness of the metasurface can also be less than the wavelength of the signal light. For example, the thickness of the metasurface can be 0.5 times the wavelength of the signal light, or 0.1 times the wavelength of the signal light, or other values, which are not specifically limited herein. Because the thickness of the metasurface is significantly less than the thickness of the liquid crystal layer, the metasurface does not generate a significant structural voltage divider, thereby avoiding a significant increase in the driving voltage of the LCOS device. Optionally, the thickness of the metasurface can be subwavelength, or other thicknesses, which are not specifically limited herein.

[0074] The above examples, combined with the accompanying figures, illustrate the implementation and operating principles of the LCOS device provided by this application. In this application, the LCOS device can also suppress crosstalk signals by arranging the orientation or size of the basic units in the metasurface, further addressing the performance degradation caused by incomplete polarization conversion. The specific implementation will be described in detail in the following examples.

[0075] Figure 5 This is a polarization conversion efficiency diagram of a metasurface provided in this application.

[0076] See also Figure 5 In this application, due to the wavelength dependence caused by material dispersion and the errors in the actual device processing process, the metasurface cannot achieve a completely 100% polarization conversion efficiency in the entire band. Therefore, there will inevitably be some residual optical signals that have not been polarized converted. The crosstalk signal includes the residual optical signal whose polarization state has not been converted after passing through the metasurface.

[0077] Figure 6 This is a schematic diagram of a crosstalk signal provided in this application.

[0078] See also Figure 6If the polarization state of the residual light that has not undergone polarization conversion is in the X direction (first direction), the phase modulation it receives is twice the phase modulation of the normal polarization-converted light, forming a +2nd order crosstalk. If the polarization state of the residual light that has not undergone polarization conversion is in the Y direction (second direction), the phase modulation it receives is 0, forming a 0th order crosstalk. The above-mentioned residual light that has not undergone polarization conversion has different propagation characteristics due to the different phase modulations obtained, thereby forming crosstalk light. In WSS, the residual light that has not undergone polarization conversion will be coupled into other ports other than the target port at different diffraction angles to form crosstalk, among which the typical crosstalk is the +2nd order diffraction order crosstalk, while the 0th order crosstalk is generally not used as an output optical signal and will not be transmitted to the output port.

[0079] In this application, in order to solve the crosstalk problem caused by residual light with unconverted polarization, a solution for joint phase modulation of a metasurface and a liquid crystal cell can be used to improve the problem. The basic idea of ​​this possible implementation method is to introduce different phases to the incident light by arranging the orientation or size of the basic units in the metasurface while performing polarization conversion on the incident light, so that the optical signal has a specific perturbed phase distribution. Then, through liquid crystal dynamic phase modulation, a compensation phase distribution complementary to the perturbed phase distribution is introduced on the basis of the beam deflection phase, so that the perturbed phase and the compensation phase generated by the joint phase modulation between the metasurface and the liquid crystal cell for the normally polarized converted signal light cancel each other out. Therefore, the normally polarized converted optical signal can maintain the original spot shape for deflection and be coupled to the output port. However, for the crosstalk light of unconverted polarization and other diffraction orders, due to the different phase modulation amounts felt, the perturbation phase and the compensation phase cannot be completely canceled out, so the spot will be diffused and cannot be efficiently coupled into the output port, thereby effectively suppressing crosstalk.

[0080] Method 1: The orientations of the basic units in the metasurface are different to suppress crosstalk signals.

[0081] Figure 7 A schematic structural diagram of a metasurface provided in this application.

[0082] See also Figure 7 In the present application, the metasurface includes a first region 401 and a second region 402. The angle between the orientation of the basic units in the first region 401 and the pixel array plane is different from the angle between the orientation of the basic units in the second region 402 and the pixel array plane. The liquid crystal cell includes a third region 403 and a fourth region 404.

[0083] In the present application, the first region can add a first phase to the optical signal whose polarization direction is converted into the first direction and the second direction. The second region can add a first phase to the optical signal having the polarization direction converted into the first direction and the second direction. Among them, the first phase and the second phase The third region can add a third phase to the optical signal with the polarization direction of the first direction output by the first region. k is an integer. The fourth region can add a fourth phase to the optical signal output from the second region with a polarization direction of the first direction. k is an integer.

[0084] When signal A undergoes normal polarization conversion in the metasurface, the joint modulation of the metasurface and the liquid crystal cell has no effect on the normally polarized converted optical signal A.

[0085] For example, when a light signal A with a polarization direction of the X direction (first direction) enters the third region of the liquid crystal cell for the first time, since the X direction is parallel to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the light signal A polarized in the X direction, and impose a phase θ on the signal A. In addition, a compensation phase θ is added to the light signal A. The signal A modulated by the liquid crystal cell is applied After the signal A is modulated by the liquid crystal cell and enters the first region of the metasurface, the metasurface can convert the polarization of the signal A to obtain the Y-polarized signal A. In addition, the metasurface can also modulate the phase of the signal A, adding an additional phase The phase of the signal A modulated by the liquid crystal cell and the metasurface is After reflection, the Y-polarized light signal A passes through the liquid crystal cell twice. Because the Y direction is perpendicular to the long axis of the liquid crystal molecules, the liquid crystal molecules cannot modulate the phase of the Y-polarized light signal A after their orientation changes. This shows that the combined modulation of the metasurface and the liquid crystal cell has no effect on the X-polarized light signal A, which is converted from normal polarization.

[0086] For example, when a light signal A with a polarization direction of the Y direction (second direction) enters the third region of the liquid crystal box for the first time. Since the Y direction is perpendicular to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the light signal A polarized in the Y direction. After passing through the liquid crystal box, the signal A enters the first region of the metasurface, and the metasurface can convert the polarization of the signal A to obtain the signal A polarized in the X direction. In addition, the metasurface can also modulate the phase of the signal A, adding an additional phase to the signal A. After the X-direction polarized light signal A is reflected, it passes through the liquid crystal cell twice. Since the Y direction is parallel to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the X-direction polarized light signal A, and impose a phase θ on the signal A. In addition, a compensation phase is added to the light signal A. The phase of the signal A modulated by the metasurface and liquid crystal cell is It can be seen that the joint modulation of the metasurface and the liquid crystal cell has no effect on the Y-polarization direction of the optical signal A converted from normal polarization.

[0087] When the polarization conversion of signal A in the metasurface is abnormal, the combined modulation of the metasurface and the liquid crystal cell will affect the optical signal A that is not polarized normally.

[0088] For example, when a light signal A with a polarization direction of the X direction (first direction) enters the third region of the liquid crystal cell for the first time, since the X direction is parallel to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the light signal A polarized in the X direction, and impose a phase θ on the signal A. In addition, a compensation phase θ is added to the light signal A. The signal A modulated by the liquid crystal cell is applied After the signal A modulated by the liquid crystal cell enters the first region of the metasurface, if the metasurface does not perform polarization conversion on the signal A, the metasurface does not modulate the phase of the signal A. After the light signal A with polarization in the X direction is reflected and passes through the liquid crystal cell a second time, the liquid crystal molecules with changed orientation will again impose a phase θ on the phase of the light signal A with polarization in the X direction entering the liquid crystal cell a second time, and will also add a compensation phase to the light signal A. The phase of the signal A modulated twice by the liquid crystal cell is Similarly, when the optical signal B with the polarization direction of the X direction (first direction) enters the fourth area, the second area, and then passes through the fourth area, the phase of the signal A modulated twice by the liquid crystal cell is

[0089] For example, when light signal A with polarization in the Y direction (second direction) first enters the third region of the liquid crystal cell, since the Y direction is perpendicular to the long axis of the liquid crystal molecules, the liquid crystal molecules, after undergoing alignment changes, cannot modulate the phase of light signal A polarized in the Y direction. When signal A enters the first region of the metasurface, if the metasurface does not perform polarization conversion on signal A, the metasurface does not modulate the phase of signal A. After reflection, light signal A polarized in the Y direction passes through the liquid crystal cell a second time, and the phase imposed on signal A by the liquid crystal cell and the metasurface is zero.

[0090] Similarly, when optical signal B, polarized in the Y direction (the second direction), enters the fourth region, passes through the second region, and then through the fourth region, the phase of signal A, modulated twice by the liquid crystal cell, is applied to it at 0. Since zero-order crosstalk is generally not transmitted as an output optical signal to the output port, it does not affect signal transmission.

[0091] Figure 8This is a diagram of the suppression effect of a crosstalk signal provided in this application.

[0092] In the present application, the orientation of the basic unit in the metasurface represents the angle between the basic unit and the pixel array plane in the metasurface. If the orientations of the basic units in the first area and the second area are different, and the polarization state of signal A does not change after passing through the first area, and the polarization state of signal B does not change after passing through the second area, the disturbance phase and compensation phase obtained by the unpolarized crosstalk light signal A and the crosstalk light signal B cannot be completely offset, and since the orientations of the basic units in the first area and the second area are different, the phase modulation amounts obtained by the crosstalk light signal A and the crosstalk light signal B are different, resulting in the light spot being diffused and unable to be efficiently coupled to the port output. Figure 8 , thereby achieving the suppression of crosstalk signals.

[0093] In the present application, the orientation of the basic units in the first region and the second region may optionally be at any angle, wherein the angle between the orientation of the basic units in the first region and the pixel array plane may be 45°, and the angle between the orientation of the basic units in the second region and the pixel array plane may be 135°. Optionally, the angle between the basic units and the pixel array plane may also be other angles, which are not specifically limited here.

[0094] Method 2: The sizes of the basic units in the metasurface are different to suppress crosstalk signals.

[0095] Figure 9 A schematic structural diagram of a metasurface provided in this application.

[0096] See also Figure 9 In the present application, the metasurface includes a first region 501 and a second region 502 , the size of the basic unit in the first region 501 is different from the size of the basic unit in the second region 502 , and the liquid crystal box includes a third region 503 and a fourth region 504 .

[0097] In the present application, the first region 501 adds a first phase to the received optical signal with the polarization direction of the first direction and the second direction. The second region 502 adds a second phase to the received optical signals with polarization directions of the first direction and the second direction. First Phase and the second phase The third region 503 adds a third phase to the optical signal with the polarization direction of the first direction output by the first region. k is an integer. The fourth region 504 adds a fourth phase to the optical signal output from the second region with the polarization direction of the first direction. k is an integer.

[0098] When signal A undergoes normal polarization conversion in the metasurface, the joint modulation of the metasurface and the liquid crystal cell has no effect on the normally polarized converted optical signal A.

[0099] For example, when a light signal A with a polarization direction of the X direction (first direction) enters the third region of the liquid crystal cell for the first time, since the X direction is parallel to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the light signal A polarized in the X direction, and impose a phase θ on the signal A. In addition, a compensation phase θ is added to the light signal A. The signal A modulated by the liquid crystal cell is applied After the signal A is modulated by the liquid crystal cell and enters the first region of the metasurface, the metasurface can convert the polarization of the signal A to obtain the Y-polarized signal A. In addition, the metasurface can also modulate the phase of the signal A, adding an additional phase The phase of the signal A modulated by the liquid crystal cell and the metasurface is After reflection, the Y-polarized light signal A passes through the liquid crystal cell twice. Because the Y direction is perpendicular to the long axis of the liquid crystal molecules, the liquid crystal molecules cannot modulate the phase of the Y-polarized light signal A after their orientation changes. This shows that the combined modulation of the metasurface and the liquid crystal cell has no effect on the X-polarized light signal A, which is converted from normal polarization.

[0100] For example, when a light signal A with a polarization direction of the Y direction (second direction) enters the third region of the liquid crystal box for the first time. Since the Y direction is perpendicular to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the light signal A polarized in the Y direction. After passing through the liquid crystal box, the signal A enters the first region of the metasurface, and the metasurface can convert the polarization of the signal A to obtain the signal A polarized in the X direction. In addition, the metasurface can also modulate the phase of the signal A, adding an additional phase to the signal A. After the X-direction polarized light signal A is reflected, it passes through the liquid crystal cell twice. Since the Y direction is parallel to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the X-direction polarized light signal A, and impose a phase θ on the signal A. In addition, a compensation phase is added to the light signal A. The phase of the signal A modulated by the metasurface and the liquid crystal cell is It can be seen that the joint modulation of the metasurface and the liquid crystal cell has no effect on the Y-polarization direction of the optical signal A converted from normal polarization.

[0101] When the polarization conversion of signal A in the metasurface is abnormal, the combined modulation of the metasurface and the liquid crystal cell will affect the optical signal A that is not polarized normally.

[0102] For example, when a light signal A with a polarization direction of the X direction (first direction) enters the third region of the liquid crystal cell for the first time, since the X direction is parallel to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the light signal A polarized in the X direction, and impose a phase θ on the signal A. In addition, a compensation phase θ is added to the light signal A. The signal A modulated by the liquid crystal cell is applied After the signal A is modulated by the liquid crystal cell and enters the first region of the metasurface, if the metasurface does not perform polarization conversion on the signal A, the metasurface still adds a perturbation phase to the signal A. After the X-direction polarized light signal A is reflected, it passes through the liquid crystal cell twice. The liquid crystal molecules after the orientation change again add a phase θ to the phase of the X-direction polarized light signal A entering the liquid crystal cell twice, and also add a compensation phase to the light signal A. The phase of the signal A modulated twice by the liquid crystal cell is Similarly, when the optical signal B with the polarization direction of the X direction (first direction) enters the fourth area, the second area, and then passes through the fourth area, the disturbance phases added by the first area and the second area to the signals A and B are different due to the different sizes of the basic units in the first area and the second area. Correspondingly, the compensation phases added by the third area and the fourth area in the liquid crystal cell to the signals A and B are also different. The phase applied to the signal B after two modulations by the liquid crystal cell is

[0103] For example, when a light signal A with a polarization direction of the Y direction (second direction) enters the third region of the liquid crystal cell for the first time, since the Y direction is perpendicular to the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the light signal A polarized in the Y direction. When signal A enters the first region of the metasurface, if the metasurface does not perform polarization conversion on signal A, the metasurface still applies a perturbation phase to the phase of signal A. The light signal A polarized in the Y direction is reflected and passes through the liquid crystal cell twice. The phase imposed on the signal A by the liquid crystal cell is 0. After the liquid crystal cell and the metasurface work together, the phase imposed on the signal A is

[0104] Similarly, when the optical signal B with polarization direction Y (second direction) enters the fourth area, the second area, and then passes through the fourth area, the disturbance phases added by the first area and the second area to the signals A and B are different due to the different sizes of the basic units in the first area and the second area. The phase of the modulated signal B is

[0105] Figure 10 This is another diagram of the suppression effect of crosstalk signals provided by this application.

[0106] like Figure 10 As shown, if the sizes of the basic units in the first area and the second area are different, and the polarization state of signal A does not change after passing through the first area, and the polarization state of signal B does not change after passing through the second area, the perturbation phase and compensation phase obtained by the unpolarized crosstalk optical signal A and the crosstalk optical signal B cannot be completely offset. Since the sizes of the basic units in the first area and the second area are different, the phase modulation amounts obtained by the crosstalk optical signal A and the crosstalk optical signal B are different, resulting in the light spot being diffused and unable to be efficiently coupled to the port output, thereby achieving the suppression of the crosstalk signal. In this possible implementation method, different perturbation phases can be obtained by adjusting the size of the basic unit, which improves the freedom of the LCOS device to set the perturbation phase.

[0107] The above examples illustrate various application modes of the LCOS device. The following examples will describe in detail possible implementation structures of the LCOS device provided in this application in conjunction with the accompanying drawings.

[0108] Structure 1:

[0109] Figure 11 This is a schematic structural diagram of another LCOS device provided in this application.

[0110] See also Figure 11 In the present application, optionally, the electrode layer may further include a metal electrode 306 .

[0111] In this application, the first surface of the liquid crystal cell 302 is covered with the first transparent electrode 301, and the second surface of the liquid crystal cell 302 is covered with the first surface of the metasurface 303. The second surface of the metasurface 303 is covered with the first surface of the metal electrode 306. The second surface of the metal electrode 306 is covered with the driving circuit 305. The metal electrode 306 can reflect the received optical signal, that is, the metal electrode 306 can reflect the optical signal output by the metasurface 303.

[0112] In this possible implementation, the metasurface can be directly processed on the traditional LCOS backplane without changing the original backplane structure. The processing is more convenient and saves processing costs.

[0113] Structure 2:

[0114] Figure 12 This is a schematic structural diagram of another LCOS device provided in this application.

[0115] See also Figure 12 In the present application, optionally, the electrode layer includes a second transparent electrode 307 and a metal plate 308 .

[0116] In this application, the first surface of the liquid crystal cell 302 is covered with the first transparent electrode 301, and the second surface of the liquid crystal cell 302 is covered with the first surface of the second transparent electrode 307. The second surface of the second transparent electrode 307 is covered with the first surface of the metasurface 303. The second surface of the metasurface 303 is covered with the first surface of the metal plate 308. The second surface of the metal plate 308 is covered with the driving circuit 305. The metal plate 308 can reflect the received optical signal, that is, the metal plate 308 can reflect the optical signal output by the metasurface 303.

[0117] Structure three:

[0118] Figure 13 This is a schematic structural diagram of another LCOS device provided in this application.

[0119] See also Figure 13 In the present application, optionally, the electrode layer includes a second transparent electrode 307 .

[0120] In this application, the first surface of the liquid crystal cell 302 is covered with the first transparent electrode 301, and the second surface of the liquid crystal cell 302 is covered with the first surface of the second transparent electrode 307. The second surface of the second transparent electrode 307 is covered with the first surface of the metasurface 303. The second surface of the metasurface 303 is covered with the driving circuit 305. The metasurface 303 can also reflect received light signals.

[0121] In the implementations described in Structure 2 and Structure 3, the metasurface 303 is arranged outside the first transparent electrode 301 and the second transparent electrode 307, thereby avoiding the structural voltage division generated by the metasurface 303 and reducing the driving voltage of the LCOS device.

[0122] It can be understood that in addition to the three possible implementation methods of Structure 1 to Structure 3 mentioned above, the LCOS device provided in this application can also have other structures, which are not specifically limited here.

[0123] In the present application, the metasurface includes basic units. Optionally, the material of the basic units may include gold, silver, aluminum, platinum, chromium, silicon, silicon nitride, titanium dioxide or aluminum oxide. The material of the basic units may also include other materials, which are not specifically limited here.

[0124] In the present application, optionally, the shape of the basic unit includes a polygonal prism or an elliptical cylinder. The shape of the basic unit can also be other shapes such as a cube, which is not specifically limited here.

[0125] In the present application, optionally, the metasurface may further include a planarization material, and the basic unit is contained in the planarization material. The planarization material may include silicon dioxide, aluminum oxide, silicon nitride or silicon. The planarization material may also include other materials, which are not specifically limited here.

[0126] In the present application, the LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of a received optical signal with a first polarization direction into a second direction, and convert the polarization direction of a received optical signal with a second polarization direction into the first direction. The liquid crystal cell can adjust the phase of the optical signal with a first polarization direction in the optical signal output by the first transparent electrode and the metasurface according to the target voltage. Thus, it can be seen that the LCOS device can perform polarization diversity processing and conversion processing on the optical signal through the metasurface. The implementation method of the metasurface is simple, the volume is small, the complexity of the device is reduced, the construction cost of the device is reduced, and it is more conducive to the promotion of technology.

[0127] The WSS and LCOS devices provided by this application have been described in detail above. Specific examples have been used herein to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are intended only to facilitate understanding of the method and core concepts of this application. Furthermore, those skilled in the art will appreciate that variations in the specific implementation methods and scope of application may occur based on the concepts of this application. In summary, this specification should not be construed as limiting this application.

Claims

1. A liquid crystal on silicon (LCOS) device, characterized in that: The LCOS device includes a first transparent electrode, a liquid crystal cell, a metasurface, an electrode layer, and a driving circuit, wherein the thickness of the metasurface is on the order of wavelength or sub-wavelength; The first transparent electrode is used to receive an incident light signal, wherein the polarization direction of the incident light signal includes a first direction and a second direction, wherein the first direction is used to represent a direction parallel to a target intersection line, wherein the target intersection line represents an intersection line between a pixel array plane and a liquid crystal rotation plane, and the second direction is used to represent a direction perpendicular to the liquid crystal rotation plane; The metasurface is configured to convert the polarization direction of a received optical signal having the first polarization direction into the second direction, and convert the polarization direction of a received optical signal having the second polarization direction into the first direction; The driving circuit is used to configure a target voltage, where the target voltage is used to represent the voltage between the first transparent electrode and the electrode layer; The liquid crystal cell is used to adjust, according to the target voltage, a phase of an optical signal having a polarization direction in the first direction, among optical signals output by the first transparent electrode and the metasurface.

2. The LCOS device according to claim 1, wherein: The orientations or sizes of the basic units in the metasurface are different to suppress crosstalk signals, wherein the crosstalk signals include optical signals whose polarization states are not converted after passing through the metasurface.

3. The LCOS device according to claim 2, wherein: The metasurface includes a first region and a second region, wherein an angle between an orientation of basic units in the first region and the pixel array plane is different from an angle between an orientation of basic units in the second region and the pixel array plane, and the liquid crystal cell includes a third region and a fourth region; The first region is used to add a first phase φ1 to the optical signal having the first direction and the second direction after the polarization direction is converted; The second region is used to add a second phase φ2 to the optical signal having the first direction and the second direction after the polarization direction is converted, and the first phase φ1 and the second phase φ2 are different; The third region is used to add a third phase -φ1+2kπ to the optical signal output by the first transparent electrode and the first region, the polarization direction of which is the first direction, where k is an integer; The fourth region is used to add a fourth phase -φ2+2kπ to the optical signal output by the first transparent electrode and the second region with the polarization direction in the first direction, where k is an integer.

4. The LCOS device according to claim 3, wherein: The included angle between the orientation of the basic units in the first region and the pixel array plane is 45 degrees, and the included angle between the orientation of the basic units in the second region and the pixel array plane is 135 degrees.

5. The LCOS device according to claim 2, wherein: The metasurface includes a first region and a second region, the size of the basic unit in the first region is different from the size of the basic unit in the second region, and the liquid crystal cell includes a third region and a fourth region; The first region is used to add a first phase φ1 to the received optical signal having the polarization directions of the first direction and the second direction; The second region is used to add a second phase φ2 to the received optical signal having the polarization directions of the first direction and the second direction, and the first phase φ1 and the second phase φ2 are different; The third region is used to add a third phase -φ1+2kπ to the optical signal output by the first transparent electrode and the first region, the polarization direction of which is the first direction, where k is an integer; The fourth region is used to add a fourth phase -φ2+2kπ to the optical signal output by the first transparent electrode and the second region with the polarization direction in the first direction, where k is an integer.

6. The LCOS device according to any one of claims 1 to 5, wherein: The electrode layer includes a metal electrode; The first surface of the liquid crystal cell is covered with the first transparent electrode, and the second surface of the liquid crystal cell is covered with the first surface of the metasurface; The second surface of the metasurface covers the first surface of the metal electrode; The second surface of the metal electrode covers the driving circuit; The metal electrode is used to reflect the received optical signal.

7. The LCOS device according to any one of claims 1 to 5, wherein: The electrode layer includes a second transparent electrode and a metal plate; The first surface of the liquid crystal cell is covered with the first transparent electrode, and the second surface of the liquid crystal cell is covered with the first surface of the second transparent electrode; The second surface of the second transparent electrode covers the first surface of the metasurface; The second surface of the metasurface covers the first surface of the metal plate; The second surface of the metal plate covers the driving circuit; The metal plate is used to reflect the received optical signal.

8. The LCOS device according to any one of claims 1 to 5, wherein: The electrode layer includes a second transparent electrode; The first surface of the liquid crystal cell is covered with the first transparent electrode, and the second surface of the liquid crystal cell is covered with the first surface of the second transparent electrode; The second surface of the second transparent electrode covers the first surface of the metasurface; The second surface of the metasurface covers the driving circuit; The metasurface is also used to reflect received optical signals.

9. The LCOS device according to any one of claims 2 to 5, wherein: The material of the basic unit includes gold, silver, aluminum, platinum, chromium, silicon, silicon nitride, titanium dioxide or aluminum oxide.

10. The LCOS device according to any one of claims 2 to 5, wherein: The basic unit may be in the shape of a polygonal column or an elliptical column.

11. The LCOS device according to any one of claims 1 to 5, wherein: The metasurface further includes a planarization material, which includes silicon dioxide, aluminum oxide, silicon nitride, or silicon.

12. A wavelength selective switch WSS, characterized in that: The WSS includes the LCOS device according to any one of claims 1 to 11.

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