CN116165820A - A liquid crystal on silicon LCOS device and a wavelength selective switch WSS - Google Patents

Abstract

The present application provides a liquid crystal on silicon 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 the received optical signal whose polarization direction is the first direction to a second direction, and convert the received polarization direction to the second direction The polarization direction of the optical signal is converted to the first direction. The liquid crystal cell can adjust the phase of the optical signal whose polarization direction is the first direction among the optical signals 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 optical signals through the metasurface. The implementation of the metasurface is simple, occupies a small volume, reduces the complexity of the equipment, reduces the construction cost of the equipment, and is more conducive to the realization of technology promotion.

Description

A liquid crystal on silicon LCOS device and a wavelength selective switch WSS

technical field

The present application relates to the communication field, in particular to a Liquid Crystal on Silicon (LCOS) device and a Wavelength Selective Switch (WSS).

Background technique

LCOS is a miniaturized reflective active matrix liquid crystal display or "microdisplay". LCOS devices are also known as spatial light modulators. The top of the silicon substrate in LCOS devices is covered with a layer of liquid crystals that modulate the light field. The LCOS device has many advantages such as flexible control of the light field, rewritable rewritable, and high resolution. Therefore, the LCOS device has been widely used in many fields.

In the conventional technology, the material of the liquid crystal layer in the LCOS device is mainly nematic liquid crystal. Nematic liquid crystals are mainly composed of non-polar rod-shaped liquid crystal molecules and have uniaxial crystal characteristics. When a traditional LCOS device implements light field phase modulation, it is assumed that the plane where the LCOS device is located is defined as the XY plane, and the normal direction of the XY plane is defined as the Z direction. In the XY plane, the orientation of the long axis of liquid crystal molecules under no voltage is defined as the X direction, and the direction perpendicular to both the X and Z directions is defined as the Y direction. When a voltage is applied to a conventional LCOS device, the orientation of the liquid crystal molecules can be rotated from the X direction to the Z direction. When the voltage is different, the orientation of the liquid crystal molecules rotates at different angles from the X direction to the Z direction. Therefore, the orientations of the liquid crystal molecules under different voltages are different directions in the XZ plane. At this time, the incident light polarized in the X direction corresponds to extraordinary light (e-light for short), and its refractive index will change with the orientation of the liquid crystal molecules. Therefore, under the condition that the thickness of the liquid crystal layer remains unchanged, adjusting the voltage applied to the LCOS device can achieve phase modulation of the incident light polarized in the X direction. The incident light polarized in the Y direction corresponds to ordinary light, referred to as o-light, whose refractive index does not change with the orientation of the liquid crystal molecules, and phase modulation cannot be realized.

In a traditional LCOS device, when the incident light has polarization components in both X and Y directions, it is usually necessary to perform polarization diversity processing and conversion processing on the optical signal by means of a peripheral optical path including multiple components. In the equipment including the traditional LCOS device, the peripheral optical path needs to be set up. The peripheral optical path has a complex structure and occupies a large volume, which increases the complexity of the equipment and increases the construction cost of the equipment.

Contents of the invention

The present application provides a liquid crystal on silicon LCOS device and a wavelength selective switch WSS. The WSS includes the LCOS device, and the LCOS device can perform polarization diversity processing and conversion processing on optical signals through a metasurface. The implementation of the metasurface is simple, occupies a small volume, reduces the complexity of the equipment, reduces the construction cost of the equipment, and is more conducive to the realization of technology promotion.

The first aspect of 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, and the thickness of the metasurface includes Sub-wavelength order; the first transparent electrode is used to receive the incident light signal, the polarization direction of the incident light signal includes a first direction and a second direction, and the first direction is used to represent the direction parallel to the target intersection line direction, the target intersection line is used to indicate the intersection line between the pixel array plane and the liquid crystal rotation plane, and the second direction is used to indicate a direction perpendicular to the liquid crystal rotation plane; the metasurface is used to receive converting the polarization direction of the optical signal whose polarization direction is the first direction to the second direction, and converting the polarization direction of the received optical signal whose polarization direction is the second direction to the first direction; The drive circuit is used to configure a target voltage, and 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 the first transparent electrode according to the target voltage. Among the optical signals output by the transparent electrode and the metasurface, the polarization direction is the phase of the optical signal in the first direction.

In the present application, the LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of the received optical signal whose polarization direction is the first direction to a second direction, and convert the received polarization direction to the second direction The polarization direction of the optical signal is converted to the first direction. The liquid crystal cell can adjust the phase of the optical signal whose polarization direction is the first direction among the optical signals 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 optical signals through the metasurface. The implementation of the metasurface is simple, occupies a small volume, reduces the complexity of the equipment, reduces the construction cost of the equipment, and is more conducive to the realization of technology promotion.

In a possible implementation of the first aspect, the basic units in the metasurface have different orientations or sizes, so as to suppress crosstalk signals, and the crosstalk signals include that the polarization state does not occur after passing through the metasurface converted optical signal.

In this possible implementation, in order to solve the crosstalk problem caused by the residual light of unconverted polarization, it can be improved by the joint phase modulation scheme of the metasurface and the liquid crystal cell. The basic idea of this possible implementation is to convert the polarization of the incident light while introducing different phases to the incident light through the orientation or size arrangement of the basic units in the metasurface, so that the optical signal has a specific perturbed phase distribution. . Then, a compensation phase distribution complementary to the perturbed phase distribution is introduced on the basis of the beam deflection phase through liquid crystal dynamic phase modulation, so that the normal polarization-converted signal light is generated after joint phase modulation between the metasurface and the liquid crystal cell The disturbance phase and the compensation phase cancel each other out. Therefore, the normal polarization-converted optical signal can be deflected while maintaining the original spot shape, and coupled to the output port. For crosstalk light without polarization conversion and other diffraction orders, due to the difference in the amount of phase modulation felt, the disturbance phase and compensation phase cannot be completely offset, so the light spot will be diffuse and cannot be coupled into the output port efficiently, so as to realize the anti-crosstalk effective suppression.

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所述第一相位/>

和所述第二相位/>

不相同；所述第三区域用于，对所述第一透明电极和所述第一区域输出的所述偏振方向为所述第一方向的光信号增加第三相位/>

k为整数；所述第四区域用于，对所述第一透明电极和所述第二区域输出的所述偏振方向为所述第一方向的光信号增加第四相位/>

k为整数。In a possible implementation manner of the first aspect, the metasurface includes a first region and a second region, and the angle between the orientation of the basic units in the first region and the pixel array plane and the The orientation of the basic units in the second area is different from the included angle of the pixel array plane, and the liquid crystal cell includes a third area and a fourth area; the first area is used to produce a converted polarization direction for the polarization direction adding a first phase to the optical signals in the first direction and the second direction

The second region is used to add a first phase to the optical signals in the first direction and the second direction after the polarization direction is converted.

The first phase />

and the second phase />

Not the same; the third area 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 area.

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.

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 plane of the pixel array. 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, there is no crosstalk optical signal with polarization conversion The disturbance phase and compensation phase obtained by A and the crosstalk optical signal B cannot be completely canceled out, and because the orientations of the basic units in the first area and the second area are different, the phase modulations obtained by the crosstalk optical signal A and the crosstalk optical signal B are not the same Similarly, the light spot is diffused so that it cannot be efficiently coupled to the port output, thereby achieving the suppression of crosstalk signals. In this possible implementation mode, the basic units in the metasurface have the same size, the design and processing of the metasurface are easier to realize, and the processing cost of the LCOS device is reduced.

In a possible implementation manner of the first aspect, the angle between the orientation of the basic units in the first region and the plane of the pixel array is 45 degrees, and the orientation of the basic units in the second region The included angle with the plane of the pixel array is 135 degrees.

In this possible implementation, the angle between the orientation of the basic unit in the first region and the pixel array plane is 45°, and the angle between the orientation of the basic unit in the second region and the pixel array plane is 135°, The phase modulation of 0 and π can be respectively introduced while realizing the polarization conversion, and this possible realization method improves the suppression effect of the LCOS device on the crosstalk signal.

所述第二区域用于，对接收到的偏振方向为所述第一方向和所述第二方向的光信号增加第二相位/>

所述第一相位/>

和所述第二相位/>

不相同；所述第三区域用于，对所述第一透明电极和所述第一区域输出的所述偏振方向为所述第一方向的光信号增加第三相位/>

k为整数；所述第四区域用于，对所述第一透明电极和所述第二区域输出的所述偏振方向为所述第一方向的光信号增加第四相位

k为整数。In a possible implementation manner of the first aspect, the metasurface includes a first region and a second region, the size of the basic unit in the first region and the size of the basic unit in the second region Different, the liquid crystal cell includes a third area and a fourth area; the first area is used to add a first phase to the received optical signal whose polarization direction is the first direction and the second direction

The second region is used to add a second phase to the received optical signal whose polarization direction is the first direction and the second direction

The first phase />

and the second phase />

Not the same; the third area 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 area.

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.

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 disturbance phase and compensation phase obtained by the unpolarized crosstalk optical signal A and crosstalk optical signal B cannot be completely canceled out, and because the size of the basic unit in the first area and the second area is different, therefore, the crosstalk optical signal A and the crosstalk optical signal The amount of phase modulation obtained by B is different, resulting in the dispersion of the light spot, so that it cannot be efficiently coupled to the port output, thereby realizing the suppression of the crosstalk signal. In this possible implementation manner, different perturbation phases can be obtained by adjusting the size of the basic unit, which improves the degree of freedom for setting the perturbation phase of the LCOS device.

In a possible implementation manner of the first aspect, 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 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 drive circuit; the metal electrode is used for, Reflects the received optical signal.

In this possible implementation, a possible structure of an LCOS device is provided. 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 the processing cost is saved.

In a possible implementation manner of the first aspect, 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 transparent electrode of the liquid crystal cell The surface covers 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 metal The first surface of the plate; the second surface of the metal plate covers the drive circuit; the metal plate is used to reflect the received optical signal.

In this possible implementation manner, the metasurface is arranged outside the first transparent electrode and the second transparent electrode, which avoids structural voltage division generated by the metasurface and reduces the driving voltage of the LCOS device.

In a possible implementation manner of the first aspect, 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 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 drive circuit; The metasurface is also used to reflect the received optical signal.

In this possible implementation, the metasurface is arranged outside the first transparent electrode and the second transparent electrode, which avoids structural voltage division generated by the metasurface, reduces the driving voltage of the LCOS device, and saves energy.

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

In this possible implementation, if the material of the basic unit is a metal material, 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 material of the basic unit is a non-metallic material, the loss of the optical signal passing through the metasurface can be reduced.

In a possible implementation manner of the first aspect, the shape of the basic unit includes a polygonal prism or an elliptical prism.

In this possible implementation manner, two possible implementation manners of the basic unit are provided, which improves the feasibility of the solution.

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

In this possible implementation manner, a possible implementation manner of the planarization material is provided, which improves the feasibility of the solution.

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

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

The second aspect of the present application provides a wavelength selective switch WSS, and the WSS includes the LCOS device as described in the first aspect or any possible implementation manner of the first aspect.

The WSS provided in this application includes LCOS devices. The LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of the received optical signal whose polarization direction is the first direction to a second direction, and convert the received optical signal whose polarization direction is the second direction The polarization direction of is converted to the first direction. The liquid crystal cell can adjust the phase of the optical signal whose polarization direction is the first direction among the optical signals 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 optical signals through the metasurface. The implementation of the metasurface is simple, occupies a small volume inside the WSS, reduces the complexity of the equipment, reduces the construction cost of the WSS, and makes the WSS more conducive to the realization of technology promotion.

Description of drawings

FIG. 1 is a schematic structural diagram of a WSS provided by the present application;

Fig. 2 is a kind of structural representation of a kind of LCOS provided by the present application;

Fig. 3 is a kind of schematic structural diagram of a kind of liquid crystal cell provided by the present application;

FIG. 4 is a schematic diagram of an application of an LCOS device provided by the present application;

Fig. 5 is the polarization conversion efficiency figure of a kind of metasurface provided in the application;

FIG. 6 is a schematic diagram of a crosstalk signal provided in the present application;

FIG. 7 is a schematic structural view of a metasurface provided by the present application;

FIG. 8 is a suppression effect diagram of a crosstalk signal provided by the present application;

Fig. 9 is another structural schematic diagram of a metasurface provided by the present application;

FIG. 10 is a suppression effect diagram of another crosstalk signal provided by the present application;

FIG. 11 is a schematic structural diagram of another LCOS device provided by the present application;

FIG. 12 is a schematic structural diagram of another LCOS device provided by the present application;

FIG. 13 is a schematic structural diagram of another LCOS device provided by the present application.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only part of the present application, not all of them. . Those skilled in the art know that, with the emergence of new application scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

The terms "first", "second" and the like in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or modules is not necessarily limited to the expressly listed Instead, other steps or modules not explicitly listed or inherent to the process, method, product or apparatus may be included. The naming or numbering of the steps in this application does not mean that the steps in the method flow must be executed in the time/logic sequence indicated by the naming or numbering. The execution order of the technical purpose is changed, as long as the same or similar technical effect can be achieved.

Liquid Crystal on Silicon (LCOS) is a miniaturized reflective active matrix liquid crystal display device or "micro display device". LCOS devices are also known as spatial light modulators. The top of the silicon substrate in LCOS devices is covered with a layer of liquid crystals that modulate the light field. The LCOS device has many advantages such as flexible control of the light field, rewritable rewritable, and high resolution. Therefore, the LCOS device has been widely used in many fields.

In the conventional technology, the material of the liquid crystal layer in the LCOS device is mainly nematic liquid crystal. Nematic liquid crystals are mainly composed of non-polar rod-shaped liquid crystal molecules and have uniaxial crystal characteristics. When a traditional LCOS device implements light field phase modulation, it is assumed that the plane where the LCOS device is located is defined as the XY plane, and the normal direction of the XY plane is defined as the Z direction. In the XY plane, the orientation of the long axis of liquid crystal molecules under no voltage is defined as the X direction, and the direction perpendicular to both the X and Z directions is defined as the Y direction. When a voltage is applied to a conventional LCOS device, the orientation of the liquid crystal molecules can be rotated from the X direction to the Z direction. When the voltage is different, the orientation of the liquid crystal molecules rotates at different angles from the X direction to the Z direction. Therefore, the orientations of the liquid crystal molecules under different voltages are different directions in the XZ plane. At this time, for the incident light polarized in the X direction, it corresponds to extraordinary light, and its refractive index will change with the orientation of the liquid crystal molecules. Therefore, under the condition that the thickness of the liquid crystal layer remains unchanged, adjusting the voltage applied to the LCOS device can achieve phase modulation of the incident light polarized in the X direction. The incident light polarized in the Y direction corresponds to ordinary light, and its refractive index will not change with the orientation of the liquid crystal molecules, so phase modulation cannot be realized.

In a traditional LCOS device, when the incident light has polarization components in both X and Y directions, it is usually necessary to perform polarization diversity processing and conversion processing on the optical signal by means of a peripheral optical path including multiple components. In the equipment including the traditional LCOS device, the peripheral optical path needs to be set up. The peripheral optical path has a complex structure and occupies a large volume, which increases the complexity of the equipment and increases the construction cost of the equipment.

Aiming at the above-mentioned problems existing in the existing LCOS device, the present application provides an LCOS device and WSS. The implementation of the metasurface in the LCOS device is simple, occupies a small volume, reduces the complexity of the equipment, and reduces the equipment cost. The construction cost is more conducive to the realization of technology promotion.

The LCOS device provided in the present application and the WSS including the LCOS device will be described in detail below in conjunction with the accompanying drawings in the present application. Firstly, the WSS provided in the present application will be introduced.

FIG. 1 is a schematic structural diagram of a WSS provided in the present application.

Please refer to FIG. 1. In this application, the device for routing optical signals in a reconfigurable optical add/drop multiplexer (reconfigurable optical add/dropmultiplexer, ROADM) is a WSS, and the WSS shown in FIG. 1 includes the WSS provided by this application. LCOS. As shown in Figure 1, WSS includes input and output components, dispersion components, spot transformation components and LCOS.

In this application, a schematic structural diagram of a WSS including LCOS is shown in FIG. 1 . After the input and output components receive the multiplexed signal, the dispersion component can spatially separate the multiplexed signal light emitted from the input port according to different wavelengths. The light spot transformation component can project the separated optical signal to different regions in the LCOS device. The LCOS device performs phase modulation on different incident light wavelengths to achieve the deflection of the optical signal, and the deflected optical signal is transmitted to different output ports through the spot transformation component and the dispersion component again, so that the optical signals of different wavelengths are selectively routed to the same or different output port.

It can be understood that, optionally, the LCOS device provided by this application can be applied to WSS, the LCOS device provided by this application can also be applied to a holographic display device, and the LCOS device can also be applied to a laser radar device. This application provides The LCOS device can also be used in other equipment, which is not limited here.

The WSS provided in this application includes LCOS devices. The LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of the received optical signal whose polarization direction is the first direction to a second direction, and convert the received optical signal whose polarization direction is the second direction The polarization direction of is converted to the first direction. The liquid crystal cell can adjust the phase of the optical signal whose polarization direction is the first direction among the optical signals 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 optical signals through the metasurface. The implementation of the metasurface is simple, occupies a small volume inside the WSS, reduces the complexity of the equipment, reduces the construction cost of the WSS, and makes the WSS more conducive to the realization of technology promotion.

The above example introduces the WSS provided by the present application, and the LCOS device provided by the present application will be described in detail below based on the WSS introduced above and with reference to the accompanying drawings.

FIG. 2 is a schematic structural diagram of an LCOS provided in the present application.

Please refer to FIG. 2. In the present application, the LCOS device 201 includes a first transparent electrode 301, a liquid crystal cell 302, a metasurface 303, an electrode layer 304, and a driving circuit 305, wherein the thickness of the metasurface includes wavelength order or sub- wavelength magnitude.

The functions of each component in the LCOS device will be described in detail below.

In this application, the first transparent electrode 301 may receive incident light signals, which may include light signals of various polarization directions, and the polarization directions of the incident light signals include a first direction and a second direction. Wherein, the first direction is used to indicate the direction parallel to the target intersection line, the target intersection line is used to indicate the intersection line between the pixel array plane and the liquid crystal rotation plane, and the second direction is used to indicate the direction perpendicular to the liquid crystal rotation plane.

In this application, the metasurface 303 can convert the polarization direction of the received optical signal whose polarization direction is the first direction to the second direction, and convert the polarization direction of the received optical signal whose polarization direction is the second direction to the second direction. one direction.

In the present application, the driving circuit 305 can configure a target voltage, and the target voltage is used to represent the voltage between the first transparent electrode 301 and the electrode layer 304 .

In this application, the liquid crystal cell 302 can adjust the phase of the optical signal whose polarization direction is the first direction among the optical signals output by the first transparent electrode and the metasurface according to the target voltage.

First, a specific example is used to illustrate the first direction and the second direction included in the polarization direction of the incident optical signal received by the first transparent electrode in this application.

FIG. 3 is a schematic structural diagram of a liquid crystal cell provided in the present application.

Exemplarily, as shown in FIG. 3 , the liquid crystal cells in current mainstream LCOS devices mainly include nematic liquid crystals, which are composed of nonpolar rod-shaped liquid crystal molecules and have the characteristics of uniaxial crystals. For the convenience of description, the plane where the pixels in the liquid crystal cell are located is defined as the pixel array plane, that is, the XOY plane in the figure. The normal direction of the XOY plane is defined as the Z direction, corresponding to the electric field application direction. The orientation of the long axis of liquid crystal molecules under no voltage is defined as the X direction, that is, the first direction, and the direction that is orthogonal to both the X and Z directions is defined as the Y direction, that is, the second direction. The orientation of the liquid crystal molecules can be rotated from the X direction to the Z direction by applying a voltage, and the XOZ plane is defined as the liquid crystal rotation plane. The alignment of liquid crystal molecules along different directions of the XOZ plane under different voltages corresponds to different birefringence conditions. At this time, for the incident light polarized in the X direction, corresponding to extraordinary light, its refractive index will change with the orientation of the liquid crystal molecules, so when the thickness of the liquid crystal molecules remains unchanged, different phases can be achieved according to different voltages modulation. For the incident light polarized in the Y direction, which corresponds to ordinary light, its refractive index will not change with the orientation of the liquid crystal molecules, and phase modulation cannot be realized.

In the following, a working process of the LCOS provided by the present application will be introduced with a specific example in combination with the above examples.

FIG. 4 is a schematic diagram of an application of an LCOS device provided in the present application.

Please refer to FIG. 4 , in this application, the optical signal A with the polarization direction in the X direction (the first direction) enters the liquid crystal cell for the first time after passing through the first transparent electrode. The liquid crystal molecules in the liquid crystal cell 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 light signal A polarized in the X direction. Phase, to apply a phase θ to signal A. Subsequently, the signal A enters the metasurface, and the metasurface can perform polarization conversion on the signal A. After the polarization conversion, the polarization state of the signal A is rotated by 90° and becomes an optical signal polarized in the Y direction (the second direction). The optical signal A polarized in the Y direction passes through the liquid crystal cell for the second time 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 optical signal A polarized in the Y direction, as shown in Figure 4. It can be seen that the LCOS device can perform phase modulation on the optical signal A in the X polarization direction.

In the present application, the optical signal A whose polarization direction is in the Y direction (the second direction) enters the liquid crystal cell for the first time after passing through the first transparent electrode. The liquid crystal molecules in the liquid crystal cell are subjected to the voltage between the first transparent electrode and the electrode layer to produce orientation changes. 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 optical signal A polarized in the Y direction. phase. Subsequently, the signal A enters the metasurface, and the metasurface can perform polarization conversion on the signal A. After the polarization conversion, the polarization state of the signal A is rotated by 90° and becomes an optical signal polarized in the X direction (the first direction). The optical signal A polarized in the X direction passes through the liquid crystal cell for the second time after being reflected. Since the X direction is parallel to the long axis orientation of the liquid crystal molecules, the liquid crystal molecules after orientation change can modulate the phase of the optical signal A polarized in the X direction, as shown in Figure 4. Signal A imposes a phase θ. It can be seen that the LCOS device can perform phase modulation on the optical signal A in the Y polarization direction.

To sum up, no matter for X-polarized or Y-polarized incident light, the same phase modulation of liquid crystal molecules can be obtained once during the whole process from entering the LCOS device to finally exiting. The optical signal with other arbitrary polarization states in the incident light can always be decomposed into a combination of light components with X polarization state and light components with Y polarization state, and only one phase modulation of liquid crystal molecules is obtained. Therefore, the LCOS device has polarization Independent of phase response characteristics.

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 in the present application can be much smaller than the thickness of the liquid crystal cell. Optionally, compared to the wavelength of the signal light received during operation, the thickness of the metasurface can be slightly larger than the wavelength of the signal light, for example, the thickness of the metasurface can be 2.9 times the wavelength of the signal light, the metasurface The thickness of the metasurface can be 1.5 times the wavelength of the signal light, and the thickness of the metasurface can also be other values, which are not limited here. The thickness of the metasurface can 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, the thickness of the metasurface can be 0.1 times the wavelength of the signal light, and the thickness of the metasurface can be less than 0.5 times the wavelength of the signal light. It can be other values, which are not limited here. Since the thickness of the metasurface is far smaller than the thickness of the liquid crystal layer, there is no significant structural partial pressure due to the metasurface, which avoids significantly increasing the driving voltage of the LCOS device. Optionally, the thickness of the metasurface may be of subwavelength order, and the thickness of the metasurface may be other thicknesses, which are not specifically limited here.

The above examples illustrate the implementation and working principle of the LCOS device provided by this application in conjunction with the accompanying drawings. In this application, the LCOS device can also suppress crosstalk signals by arranging the orientation or size of the basic units in the metasurface, which can Further address performance degradation due to incomplete polarization conversion. The specific implementation will be described in detail in the following examples.

Fig. 5 is a graph of polarization conversion efficiency of a metasurface provided in this application.

Please refer to Figure 5. In this application, due to the wavelength dependence caused by material dispersion and errors in the actual device manufacturing process, the metasurface cannot achieve a complete 100% polarization conversion efficiency in the entire wavelength range, so there will inevitably be some unidentified The residual optical signal of polarization conversion, the crosstalk signal includes the residual optical signal whose polarization state has not been converted after passing through the metasurface.

FIG. 6 is a schematic diagram of a crosstalk signal provided in this application.

Please refer to FIG. 6 , if the polarization state of the unpolarized residual light is in the X direction (the first direction), the amount of phase modulation it receives is twice that of the normal polarization-converted light, forming +2 level crosstalk. If the polarization state of the residual light that has not undergone polarization conversion is the Y direction (the second direction), the amount of phase modulation it receives is 0, forming zero-order crosstalk. The above-mentioned residual light that has not undergone polarization conversion has different propagation characteristics due to different phase modulation, thus forming crosstalk light. In WSS, the unpolarized residual light will be coupled into other ports other than the target port at different diffraction angles to form crosstalk, where the typical crosstalk is the crosstalk of +2 order diffraction order, and the 0 order crosstalk is generally not used as output light The signal is not transmitted to the output port.

In this application, in order to solve the problem of crosstalk caused by the residual light of unconverted polarization, it can be improved through the joint phase modulation scheme of the metasurface and the liquid crystal cell. The basic idea of this possible implementation is to convert the polarization of the incident light while introducing different phases to the incident light through the orientation or size arrangement of the basic units in the metasurface, so that the optical signal has a specific perturbed phase distribution. . Then, a compensation phase distribution complementary to the perturbed phase distribution is introduced on the basis of the beam deflection phase through liquid crystal dynamic phase modulation, so that the normal polarization-converted signal light is generated after joint phase modulation between the metasurface and the liquid crystal cell The disturbance phase and the compensation phase cancel each other out. Therefore, the normal polarization-converted optical signal can be deflected while maintaining the original spot shape, and coupled to the output port. For crosstalk light without polarization conversion and other diffraction orders, due to the difference in the perceived phase modulation, the disturbance phase and the compensation phase cannot be completely offset, so the light spot will be diffuse and cannot be efficiently coupled into the output port, so as to achieve Effective suppression of crosstalk.

Method 1: The basic units in the metasurface have different orientations to suppress crosstalk signals.

Fig. 7 is a schematic structural diagram of a metasurface provided by the present application.

Please refer to FIG. 7 , in this 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 plane of the pixel array and the angle between the orientation of the basic units in the second region 402 The angle between the orientation and the plane of the pixel array is different, and the liquid crystal cell includes a third region 403 and a fourth region 404;

第二区域可以对偏振方向产生转换后的偏振方向为第一方向和第二方向的光信号增加第一相位/>

其中，第一相位/>

和第二相位/>

不相同。第三区域可以对第一区域输出的偏振方向为第一方向的光信号增加第三相位/>

k为整数。第四区域可以对第二区域输出的偏振方向为第一方向的光信号增加第四相位/>

k为整数。In the present application, the first region can generate the first phase of the optical signal after the polarization direction is converted to the first direction and the second direction

The second region can generate the first phase of the optical signal after the polarization direction is converted to the first direction and the second direction after conversion.

where the first phase />

and second phase />

Are not the same. The third area can add a third phase to the optical signal whose polarization direction is the first direction output by the first area />

k is an integer. The fourth area can add a fourth phase to the optical signal whose polarization direction output by the second area is the first direction.

k is an integer.

When the polarization conversion of the signal A normally occurs in the metasurface, the joint modulation of the metasurface and the liquid crystal cell has no effect on the normal polarization conversion of the optical signal A.

经过液晶盒调制后的信号A被施加了/>

经过液晶盒调制后的信号A进入超构表面的第一区域内，超构表面可以对信号A进行偏振转换得到Y方向偏振的信号A。此外，超构表面还可以调制信号A的相位，对信号A添加一个额外的相位/>

经过液晶盒和超构表面调制后的信号A被施加的相位为/>

Y方向偏振的光信号A反射后二次经过液晶盒，由于Y方向与液晶分子长轴取向垂直，则取向变化后的液晶分子无法调制Y方向偏振的光信号A的相位。由此可见，超构表面和液晶盒联合调制时对正常偏振转换的X偏振方向的光信号A没有影响。Exemplarily, when the optical signal A whose polarization direction is the X direction (the first direction) enters the third area of the liquid crystal cell for the first time. Since the X direction is parallel to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the optical signal A polarized in the X direction, and apply a phase θ to the signal A. In addition, a compensation phase is added to the optical signal A

The signal A modulated by the liquid crystal cell is applied />

The signal A modulated by the liquid crystal cell enters the first region of the metasurface, and the metasurface can perform polarization conversion on the signal A to obtain a signal A polarized in the Y direction. In addition, the metasurface can also modulate the phase of signal A, adding an additional phase to signal A />

The applied phase of the signal A modulated by the liquid crystal cell and the metasurface is />

The optical signal A polarized in the Y direction passes through the liquid crystal cell for the second time after being reflected. Since the Y direction is perpendicular to the long axis orientation of the liquid crystal molecules, the liquid crystal molecules after orientation change cannot modulate the phase of the optical signal A polarized in the Y direction. It can be seen that the joint modulation of the metasurface and the liquid crystal cell has no effect on the light signal A in the X polarization direction of the normal polarization conversion.

X方向偏振的光信号A反射后二次经过液晶盒，由于Y方向与液晶分子长轴取向平行，取向变化后的液晶分子可以调制X方向偏振的光信号A的相位，对信号A施加一个相位θ。此外，还会对光信号A增加一个补偿相位/>

经过超构表面和液晶盒调制后的信号A被施加的相位为/>

由此可见，超构表面和液晶盒联合调制时对正常偏振转换的Y偏振方向的光信号A没有影响。Exemplarily, when the optical signal A whose polarization direction is the Y direction (the second direction) enters the third region of the liquid crystal cell for the first time. Since the Y direction is perpendicular to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the optical signal A polarized in the Y direction. The signal A after passing through the liquid crystal cell enters the first region of the metasurface, and the metasurface can perform polarization conversion on the signal A to obtain the signal A polarized in the X direction. In addition, the metasurface can also modulate the phase of signal A, adding an additional phase to signal A

The optical signal A polarized in the X direction passes through the liquid crystal cell for the second time after being reflected. Since the Y 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 optical signal A polarized in the X direction, and a phase is applied to the signal A. theta. In addition, a compensation phase is added to the optical signal A />

The applied 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 light signal A in the Y polarization direction of the normal polarization conversion.

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

经过液晶盒调制后的信号A被施加了/>

经过液晶盒调制后的信号A进入超构表面的第一区域内，若超构表面未对信号A进行偏振转换，超构表面也并没有调制信号A的相位。X方向偏振的光信号A反射后二次经过液晶盒，则取向变化后的液晶分子对二次进入液晶盒的X方向偏振的光信号A的相位再次施加一个相位θ，且还会对光信号A增加一个补偿相位/>

两次经过液晶盒调制后的信号A被施加的相位为/>

同理可知，偏振方向为X方向(第一方向)的光信号B进入第四区域、第二区域再经过第四区域时后，两次经过液晶盒调制后的信号A被施加的相位为/>

Exemplarily, when the optical signal A whose polarization direction is the X direction (the first direction) enters the third area of the liquid crystal cell for the first time. Since the X direction is parallel to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the optical signal A polarized in the X direction, and apply a phase θ to the signal A. In addition, a compensation phase is added to the optical signal A

The signal A modulated by the liquid crystal cell is applied />

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. The light signal A polarized in the X direction passes through the liquid crystal cell for the second time after being reflected, and the liquid crystal molecules after the orientation change will apply a phase θ again to the phase of the light signal A polarized in the X direction entering the liquid crystal cell for the second time, and will also affect the light signal A add a compensation phase />

The applied phase of the signal A modulated by the liquid crystal cell twice is />

In the same way, it can be seen that when the optical signal B with the polarization direction in the X direction (first direction) enters the fourth area, the second area and then passes through the fourth area, the phase applied to the signal A modulated by the liquid crystal cell twice is / >

Exemplarily, when the optical signal A whose polarization direction is the Y direction (the second direction) enters the third region of the liquid crystal cell for the first time. Since the Y direction is perpendicular to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the optical signal A polarized in the Y direction. The signal A enters the first region of the metasurface, and if the metasurface does not perform polarization conversion on the signal A, the metasurface does not modulate the phase of the signal A either. The optical signal A polarized in the Y direction passes through the liquid crystal cell for the second time after being reflected, and the phase applied to the signal A by the liquid crystal cell and the metasurface is 0.

In the same way, it can be seen that when the optical signal B whose polarization direction is the Y direction (the second direction) enters the fourth area, the second area and then passes through the fourth area, the phase applied to the signal A modulated by the liquid crystal cell twice is 0 . The 0-level crosstalk is generally not used as an output optical signal, and will not be transmitted to the output port. Therefore, it will not affect the signal transmission.

FIG. 8 is a crosstalk signal suppression effect diagram provided by the present application.

In this application, the orientation of the basic units in the metasurface means the angle between the basic units in the metasurface and the plane of the pixel array. 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 unpolarized crosstalk optical signal A And both the perturbation phase and the compensation phase obtained by the crosstalk optical signal B cannot be completely canceled out, and because the orientations of the basic units in the first region and the second region are different, the phase modulation obtained by the crosstalk optical signal A and the crosstalk optical signal B It is not the same, which leads to the dispersion of the light spot and cannot be efficiently coupled to the port output. As shown in Figure 8, the suppression of crosstalk signals is further realized.

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

Method 2: The size of the basic units in the metasurface is different to suppress the crosstalk signal.

FIG. 9 is a schematic structural diagram of a metasurface provided by the present application.

Please refer to FIG. 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. The liquid crystal cell includes the first region 501 and the second region 502. The third area 503 and the fourth area 504 .

第二区域502对接收到的偏振方向为第一方向和第二方向的光信号增加第二相位/>

第一相位/>

和第二相位/>

不相同。第三区域503对第一区域输出的偏振方向为第一方向的光信号增加第三相位/>

k为整数。第四区域504对第二区域输出的偏振方向为第一方向的光信号增加第四相位/>

k为整数。In this application, the first region 501 adds the first phase to the received optical signal whose polarization direction is the first direction and the second direction

The second region 502 adds a second phase to the received optical signal whose polarization direction is the first direction and the second direction

first phase />

and second phase />

Are not the same. The third region 503 adds a third phase to the optical signal whose polarization direction is 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 whose polarization direction is the first direction

k is an integer.

When the polarization conversion of the signal A normally occurs in the metasurface, the joint modulation of the metasurface and the liquid crystal cell has no effect on the normal polarization conversion of the optical signal A.

经过液晶盒调制后的信号A被施加了/>

经过液晶盒调制后的信号A进入超构表面的第一区域内，超构表面可以对信号A进行偏振转换得到Y方向偏振的信号A。此外，超构表面还可以调制信号A的相位，对信号A添加一个额外的相位/>

经过液晶盒和超构表面调制后的信号A被施加的相位为/>

Y方向偏振的光信号A反射后二次经过液晶盒，由于Y方向与液晶分子长轴取向垂直，则取向变化后的液晶分子无法调制Y方向偏振的光信号A的相位。由此可见，超构表面和液晶盒联合调制时对正常偏振转换的X偏振方向的光信号A没有影响。Exemplarily, when the optical signal A whose polarization direction is the X direction (the first direction) enters the third area of the liquid crystal cell for the first time. Since the X direction is parallel to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the optical signal A polarized in the X direction, and apply a phase θ to the signal A. In addition, a compensation phase is added to the optical signal A

The signal A modulated by the liquid crystal cell is applied />

The signal A modulated by the liquid crystal cell enters the first region of the metasurface, and the metasurface can perform polarization conversion on the signal A to obtain a signal A polarized in the Y direction. In addition, the metasurface can also modulate the phase of signal A, adding an additional phase to signal A />

The applied phase of the signal A modulated by the liquid crystal cell and the metasurface is />

The optical signal A polarized in the Y direction passes through the liquid crystal cell for the second time after being reflected. Since the Y direction is perpendicular to the long axis orientation of the liquid crystal molecules, the liquid crystal molecules after orientation change cannot modulate the phase of the optical signal A polarized in the Y direction. It can be seen that the joint modulation of the metasurface and the liquid crystal cell has no effect on the light signal A in the X polarization direction of the normal polarization conversion.

X方向偏振的光信号A反射后二次经过液晶盒，由于Y方向与液晶分子长轴取向平行，取向变化后的液晶分子可以调制X方向偏振的光信号A的相位，对信号A施加一个相位θ。此外，还会对光信号A增加一个补偿相位/>

经过超构表面和液晶盒调制后的信号A被施加的相位为/>

由此可见，超构表面和液晶盒联合调制时对正常偏振转换的Y偏振方向的光信号A没有影响。Exemplarily, when the optical signal A whose polarization direction is the Y direction (the second direction) enters the third region of the liquid crystal cell for the first time. Since the Y direction is perpendicular to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the optical signal A polarized in the Y direction. The signal A after passing through the liquid crystal cell enters the first region of the metasurface, and the metasurface can perform polarization conversion on the signal A to obtain the signal A polarized in the X direction. In addition, the metasurface can also modulate the phase of signal A, adding an additional phase to signal A

The optical signal A polarized in the X direction passes through the liquid crystal cell for the second time after being reflected. Since the Y 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 optical signal A polarized in the X direction, and a phase is applied to the signal A. theta. In addition, a compensation phase is added to the optical signal A />

The applied 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 light signal A in the Y polarization direction of the normal polarization conversion.

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

经过液晶盒调制后的信号A被施加了/>

经过液晶盒调制后的信号A进入超构表面的第一区域内，若超构表面未对信号A进行偏振转换，超构表面依然对信号A添加了一个扰动相位/>

X方向偏振的光信号A反射后二次经过液晶盒，则取向变化后的液晶分子对二次进入液晶盒的X方向偏振的光信号A的相位再次施加一个相位θ，且还会对光信号A增加一个补偿相位

两次经过液晶盒调制后的信号A被施加的相位为/>

同理可知，偏振方向为X方向(第一方向)的光信号B进入第四区域、第二区域再经过第四区域后，由于第一区域和第二区域中基本单元的尺寸不同，所以第一区域和第二区域对信号A、B添加的扰动相位不同，相应的，液晶盒中第三区域和第四区域对信号A、B添加的补偿相位也不同。两次经过液晶盒调制后的信号B被施加的相位为/>

Exemplarily, when the optical signal A whose polarization direction is the X direction (the first direction) enters the third area of the liquid crystal cell for the first time. Since the X direction is parallel to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change can modulate the phase of the optical signal A polarized in the X direction, and apply a phase θ to the signal A. In addition, a compensation phase is added to the optical signal A

The signal A modulated by the liquid crystal cell is applied />

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 still adds a disturbance phase to the signal A.>

The light signal A polarized in the X direction passes through the liquid crystal cell for the second time after being reflected, and the liquid crystal molecules after the orientation change will apply a phase θ again to the phase of the light signal A polarized in the X direction entering the liquid crystal cell for the second time, and will also affect the light signal A adds a compensation phase

The applied phase of the signal A modulated by the liquid crystal cell twice is />

Similarly, it can be seen that after the optical signal B whose polarization direction is the X direction (the first direction) enters the fourth area, the second area and passes through the fourth area, since the sizes of the basic units in the first area and the second area are different, the second area The disturbance phases added by the first area and the second area to the signals A and B are different, and correspondingly, the compensation phases added by the third area and the fourth area of the liquid crystal cell to the signals A and B are also different. The applied phase of the signal B modulated by the liquid crystal cell twice is />

Y方向偏振的光信号A反射后二次经过液晶盒，液晶盒对信号A施加的相位为0，液晶盒和超构表面共同作用后信号A被施加的相位为/>

Exemplarily, when the optical signal A whose polarization direction is the Y direction (the second direction) enters the third region of the liquid crystal cell for the first time. Since the Y direction is perpendicular to the orientation of the long axis of the liquid crystal molecules, the liquid crystal molecules after the orientation change cannot modulate the phase of the optical signal A polarized in the Y direction. 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 disturbance phase to the phase of signal A

The optical signal A polarized in the Y direction passes through the liquid crystal cell for the second time after reflection, the phase applied by the liquid crystal cell to signal A is 0, and the phase applied to signal A by the liquid crystal cell and the metasurface is />

Similarly, it can be seen that when the optical signal B whose polarization direction is in the Y direction (the second direction) enters the fourth area, the second area passes through the fourth area, the size of the basic unit in the first area and the second area are different, so The phases of the perturbation added to signals A and B by the first area and the second area are different, and the phase of the modulated signal B is:

FIG. 10 is another crosstalk signal suppression effect diagram provided by the present application.

As shown in Figure 10, 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 unpolarized Both the perturbation phase and the compensation phase obtained by the converted crosstalk optical signal A and crosstalk optical signal B cannot be completely canceled, and because the size of the basic unit in the first area and the second area is different, therefore, the crosstalk optical signal A and the crosstalk optical signal The amount of phase modulation obtained by B is different, which leads to the dispersion of the light spot and cannot be efficiently coupled to the port output, thereby realizing the suppression of the crosstalk signal. In this possible implementation manner, different perturbation phases can be obtained by adjusting the size of the basic unit, which improves the degree of freedom for setting the perturbation phase of the LCOS device.

The above examples illustrate various application modes of the LCOS device, and the following examples will describe in detail the possible implementation structures of the LCOS device provided by the present application with reference to the accompanying drawings.

Structure one:

FIG. 11 is a schematic structural diagram of another LCOS device provided by the present application.

Referring to FIG. 11 , in this application, optionally, the electrode layer may further include a metal electrode 306 .

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 covers the first surface of the metal electrode 306 . The second surface of the metal electrode 306 covers the driving circuit 305 . Wherein, 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 .

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

Structure two:

FIG. 12 is a schematic structural diagram of another LCOS device provided by the present application.

Referring to FIG. 12 , in this application, optionally, the electrode layer includes a second transparent electrode 307 and a metal plate 308 .

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 covers the first surface of the metasurface 303 . The second surface of the metasurface 303 covers the first surface of the metal plate 308 . The second surface of the metal plate 308 covers 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 .

Structure three:

FIG. 13 is a schematic structural diagram of another LCOS device provided by the present application.

Referring to FIG. 13 , in this application, optionally, the electrode layer includes a second transparent electrode 307 .

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 covers the first surface of the metasurface 303 . The second surface of the metasurface 303 covers the driving circuit 305 . The metasurface 303 can also reflect received optical signals.

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, which avoids the structural partial pressure generated by the metasurface 303 and reduces the LCOS device. the drive voltage.

It can be understood that, in addition to the above three possible implementations of structures 1 to 3, the LCOS device provided in this application may also have other structures, which are not specifically limited here.

In the present application, the metasurface includes a basic unit. Optionally, the material of the basic unit may include gold, silver, aluminum, platinum, chromium, silicon, silicon nitride, titanium dioxide or aluminum oxide. The material of the basic unit may also include Other materials may be included, which are not specifically limited here.

In this application, optionally, the shape of the basic unit includes a polygonal prism or an elliptical cylinder, and the shape of the basic unit may also be other shapes such as a cube, which are not specifically limited here.

In this application, optionally, the metasurface may also include a planarization material, the basic unit is contained in the planarization material, and the planarization material may include silicon dioxide, aluminum oxide, silicon nitride or silicon, and the planarization material Other materials may also be included, which are not specifically limited here.

In the present application, the LCOS device includes a metasurface, wherein the metasurface can convert the polarization direction of the received optical signal whose polarization direction is the first direction to a second direction, and convert the received polarization direction to the second direction The polarization direction of the optical signal is converted to the first direction. The liquid crystal cell can adjust the phase of the optical signal whose polarization direction is the first direction among the optical signals 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 optical signals through the metasurface. The implementation of the metasurface is simple, occupies a small volume, reduces the complexity of the equipment, reduces the construction cost of the equipment, and is more conducive to the realization of technology promotion.

The WSS and LCOS devices provided by this application have been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of this application. The description of the above embodiments is only used to help understand the method and its core of this application. Thought. At the same time, for those skilled in the art, based on the idea of this application, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be construed as limiting the application.

Claims (12)

1. A liquid crystal on silicon LCOS device, characterized in that, said LCOS device comprises a first transparent electrode, a liquid crystal cell, a metasurface, an electrode layer and a drive circuit, and the thickness of said metasurface comprises wavelength order of magnitude or sub- wavelength magnitude; The first transparent electrode is used to receive an incident light signal, and the polarization direction of the incident light signal includes a first direction and a second direction, and the first direction is used to indicate a direction parallel to a target intersection line, and the target The intersection line is used to indicate the intersection line between the pixel array plane and the liquid crystal rotation plane, and the second direction is used to indicate a direction perpendicular to the liquid crystal rotation plane; The metasurface is used to convert the polarization direction of the received optical signal whose polarization direction is the first direction to the second direction, and convert the received polarization direction of the optical signal to the second direction converting the polarization direction to said first direction; The drive circuit is configured to configure a target voltage, and 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 the phase of the optical signal whose polarization direction is the first direction among the optical signals output by the first transparent electrode and the metasurface according to the target voltage. 2. The LCOS device according to claim 1, wherein the basic units in the metasurface have different orientations or sizes to suppress crosstalk signals, and the crosstalk signals include polarization after passing through the metasurface An optical signal whose state has not changed. 3. The LCOS device according to claim 2, wherein the metasurface comprises a first region and a second region, the angle between the orientation of the basic units in the first region and the plane of the pixel array The angle between the orientation of the basic units in the second area and the plane of the pixel array is different, and the liquid crystal cell includes a third area and a fourth area; The first region is used to add a first phase to the optical signals in the first direction and the second direction after the polarization direction is converted.

The second region is used to add a first phase to the optical signals in the first direction and the second direction after the polarization direction is converted.

The first phase />

and the second phase />

Are not the same; 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. 4. The LCOS device according to claim 3, wherein the angle between the orientation of the basic units in the first region and the plane of the pixel array is 45 degrees, and the basic units in the second region The orientation of the cells is at an angle of 135 degrees to the plane of the pixel array. 5. The LCOS device according to claim 2, wherein the metasurface comprises a first region and a second region, the size of the basic unit in the first region and the basic unit in the second region The sizes of the cells are different, and the liquid crystal cell includes a third area and a fourth area; The first region is used to add a first phase to the received optical signal whose polarization direction is the first direction and the second direction

The second region is used to add a second phase to the received optical signal whose polarization direction is the first direction and the second direction

The first phase />

and the second phase />

Are not the same; 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. 6. The LCOS device according to any one of claims 1 to 5, wherein the electrode layer comprises 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 on 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 comprises 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 drive circuit; The metal plate is used for reflecting the received optical signal. 8. The LCOS device according to any one of claims 1 to 5, wherein the electrode layer comprises 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 8, wherein the material of the basic unit comprises gold, silver, aluminum, platinum, chromium, silicon, silicon nitride, titanium dioxide or dioxide aluminum. 10. The LCOS device according to any one of claims 2 to 9, wherein the shape of the basic unit comprises a polygonal prism or an elliptical prism. 11. The LCOS device according to any one of claims 2 to 10, wherein the metasurface further comprises a planarization material, and the planarization material comprises silicon dioxide, aluminum oxide, nitride silicon or silicon. 12. A wavelength selective switch WSS, characterized in that the WSS comprises the LCOS device according to any one of claims 1 to 11.

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