Polarization independent device and apparatus, optical network system

Abstract

A polarization-independent device and apparatus, an optical network system, belong to optical technology field. The polarization-independent device comprises: superimposed liquid crystal layer and adjustment layer; the liquid crystal layer is used for carrying out first phase adjustment to the first polarization direction light component that passes under the action of electric field. The adjustment layer is used for obtaining first light beam and second light beam based on the first polarization direction light component that enters and passes through the liquid crystal layer;Wherein, the first light beam is subjected to second phase adjustment and polarization direction adjustment in the adjustment layer;Second light beam does not pass through second phase adjustment and polarization direction adjustment in the adjustment layer. The polarization direction of the first light beam is perpendicular to the polarization direction before the polarization direction adjustment of the first light beam;The propagation direction of the first light beam and the second light beam is different after passing through the liquid crystal layer. The application can solve the problem of crosstalk between ports, and the application is used for adjusting light.

Description

[0001] This application claims priority to the Chinese Patent Application No. 202210101340.8, filed on January 27, 2022, and entitled “Polarization-Independent Device and Apparatus, Optical Network System”, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the field of optical technology, in particular to a polarization-independent device and apparatus, optical network system. BACKGROUND

[0003] A wavelength selective switch (WSS) is a common device in an optical network system. The WSS has an input port and a plurality of output ports. The WSS can switch the light input from the input port to any output port.

[0004] The polarization-independent device is an important component of the WSS. The polarization-independent device includes a superimposed liquid crystal layer and an adjustment layer. The light from the input port to the polarization-independent device will be transmitted to the output port along the path of the liquid crystal layer, the adjustment layer, and the liquid crystal layer. The light from the input port to the polarization-independent device includes a first light component with a first polarization direction and a second light component with a second polarization direction, and the first polarization direction is perpendicular to the second polarization direction. The liquid crystal layer can adjust the phase of the first polarization direction light component passing through under the action of an electric field. Therefore, when the first light component and the second light component pass through the liquid crystal layer, the liquid crystal layer can adjust the phase of the first light component and does not adjust the phase of the second light component. The first light component and the second light component passing through the liquid crystal layer are adjusted by the adjustment layer after reaching the adjustment layer. The adjustment layer can adjust the polarization direction of these light components and transmit these light components with adjusted polarization direction to the liquid crystal layer. The polarization direction of the first light component with adjusted polarization direction changes from the first polarization direction to the second polarization direction, and the polarization direction of the second light component with adjusted polarization direction changes from the second polarization direction to the first polarization direction. When the first light component with adjusted polarization direction and the second light component with adjusted polarization direction pass through the liquid crystal layer, the liquid crystal layer can adjust the phase of the second light component with adjusted polarization direction and does not adjust the phase of the first light component with adjusted polarization direction. As can be seen, although the first light component and the second light component have different polarization directions, the polarization-independent device can adjust the phase of these two light components once by the liquid crystal layer. Therefore, the polarization direction does not affect the phase adjustment. After the phase adjustment, the propagation direction of the light component changes. The first light component and the second light component can be emitted to the output port after the phase adjustment once in the polarization-independent device.

[0005] However, due to manufacturing defects of the adjusting layer, the adjusting layer cannot adjust the polarization direction of all the first light components or all the second light components. If the adjusting layer does not adjust the polarization direction of part of the first light components, when the part of the first light components reaches the liquid crystal layer again, the part of the first light components will be adjusted in phase again by the liquid crystal layer, so that the first light components that need to be emitted to a certain output port can be emitted to other output ports, causing crosstalk between the ports. SUMMARY

[0006] The application provides a polarization-independent device and apparatus, and an optical network system, which can solve the problem of crosstalk between ports. The technical solution is as follows:

[0007] In a first aspect, a polarization-independent device is provided, which includes a liquid crystal layer and an adjusting layer stacked together. The liquid crystal layer is configured to adjust the phase of a first polarized light component passing through the liquid crystal layer under the action of an electric field. The adjusting layer is configured to obtain a first light beam and a second light beam based on the first polarized light component passing through the liquid crystal layer, and transmit the first light beam and the second light beam to the liquid crystal layer. The first light beam is adjusted in phase and polarization direction in the adjusting layer, while the second light beam is not adjusted in phase and polarization direction in the adjusting layer. The polarization direction adjustment is configured to change the polarization direction by 90 degrees, so that the polarization direction of the first light beam is perpendicular to the polarization direction of the first light beam before the polarization direction adjustment (the polarization direction of the first light beam before passing through the adjusting layer). The first light beam and the second light beam have different propagation directions after passing through the liquid crystal layer.

[0008] In the polarization-independent device provided by the application, the adjusting layer can transmit the first light beam adjusted in phase and polarization direction and the second light beam not adjusted in phase and polarization direction to the liquid crystal layer based on the first polarized light component passing through the liquid crystal layer. In addition, the first light beam and the second light beam have different propagation directions after passing through the liquid crystal layer. It can be seen that the light adjusted in polarization direction and the light not adjusted in polarization direction are adjusted differently in the polarization-independent device, so that the light adjusted in polarization direction and the light not adjusted in polarization direction have different propagation directions when emitted from the polarization-independent device, which can isolate the two kinds of light in space and avoid the influence of the first polarized light component not adjusted in polarization direction on the light adjustment apparatus.

[0009] Optionally, light components of at least one polarization direction are incident into the liquid crystal layer from the side of the liquid crystal layer away from the adjusting layer, and the liquid crystal layer is configured to perform first phase adjustment on light components of a first polarization direction among the light components of the at least one polarization direction under the action of an electric field. For each polarization direction among the at least one polarization direction, the adjusting layer can obtain two beams based on the light components incident into the adjusting layer and transmit the two beams to the liquid crystal layer. One of the two beams is subjected to second phase adjustment and polarization direction adjustment in the adjusting layer, and the other of the two beams is not subjected to the second phase adjustment and the polarization direction adjustment in the adjusting layer, and the polarization direction adjustment is configured to change the polarization direction by 90 degrees, and the two beams have different propagation directions after passing through the liquid crystal layer. It can be understood that when the at least one polarization direction includes a polarization direction other than the first polarization direction, the adjusting layer can also not be configured to transmit the two beams to the liquid crystal layer based on the light components of the other polarization direction incident into the adjusting layer, which is not limited in the present application.

[0010] Further, the two beams transmitted by the adjusting layer to the liquid crystal layer are subjected to different phase adjustments in the adjusting layer. Optionally, the beam that is not subjected to the second phase adjustment and the polarization direction adjustment among the two beams can also be subjected to other adjustments in the adjusting layer in addition to the second phase adjustment and the polarization direction adjustment. For example, the beam can be subjected to third phase adjustment different from the second phase adjustment in the adjusting layer, which is not limited in the present application. For example, the second beam can be subjected to third phase adjustment different from the second phase adjustment in the adjusting layer, which is not limited in the present application.

[0011] Further, the adjusting layer in the polarization-independent device provided by the present application can have various implementation manners. For example, the adjusting layer can include: functional layers and a reflective layer stacked in sequence in the direction away from the liquid crystal layer, and the reflective surface of the reflective layer faces the functional layers; and the second phase adjustment and the polarization direction adjustment occur in the functional layers. After passing through the liquid crystal layer, the light components are transmitted along the functional layers, the reflective layer, and the functional layers in sequence and reach the liquid crystal layer again, and in this process, the light components of the first polarization direction pass through the functional layers twice, and at this time, the second phase adjustment can include: one phase adjustment of the light components of the first polarization direction in the process of passing through the functional layers for the first time, and another phase adjustment of the light components of the first polarization direction in the process of passing through the functional layers for the second time. The polarization direction adjustment can include: the light components of the first polarization direction change from first linear polarization to circular polarization in the process of passing through the functional layers for the first time, and the light components of the first polarization direction change from the circular polarization to second linear polarization in the process of passing through the functional layers for the second time, and the polarization direction of the first linear polarization is perpendicular to the polarization direction of the second linear polarization.

[0012] Further, the liquid crystal layer adjusts the propagation direction of the light component of the first polarization direction by using the first phase adjustment manner, and the adjusting layer adjusts the propagation direction of the light component of the first polarization direction by using the second phase adjustment manner. In this process, the amplitude of the light is not adjusted, and thus the energy loss of the light is small.

[0013] Further, the part (e.g., the functional layer) in the adjusting layer for performing the second phase adjustment and the polarization direction adjustment can have various implementation manners, and one of the implementation manners will be taken as an example for description below.

[0014] For example, the part in the adjusting layer for performing the second phase adjustment and the polarization direction adjustment includes a plurality of adjustment structures arranged at intervals, and the plurality of adjustment structures can form a metasurface structure or other structures different from the metasurface structure. Optionally, the second phase adjustment and the polarization direction adjustment are both related to at least one parameter of material, size, shape and arrangement manner of the adjustment structure. When designing the part in the adjusting layer for performing the second phase adjustment and the polarization direction adjustment, the at least one parameter can be set according to the function that the adjusting layer needs to achieve.

[0015] Optionally, the part in the adjusting layer for performing the second phase adjustment and the polarization direction adjustment includes a plurality of adjustment structures arranged at intervals. The plurality of adjustment structures include a first adjustment structure group and a second adjustment structure group arranged alternately along a first direction. The first direction can be perpendicular to the long axis direction of the liquid crystal in the liquid crystal layer when no electric field is applied, or the first direction can be another direction, which is not limited in the present application. The included angle between the longest central axis of the adjustment structure in the first adjustment structure group and the longest central axis of the adjustment structure in the second adjustment structure group ranges from 80 degrees to 100 degrees. For example, the longest central axis of the adjustment structure in the first adjustment structure group is perpendicular to the longest central axis of the adjustment structure in the second adjustment structure group.

[0016] It should be noted that the adjustment structure has a central axis, and the adjustment structure can be symmetrical (completely symmetrical) or approximately symmetrical (not completely symmetrical) about the central axis. The adjustment structure can have one or more central axes, which are not limited in the present application. However, the one or more central axes have the longest central axis. For example, the adjustment structure can be in the shape of a rod (e.g., a cuboid, a cylinder, an elliptic cylinder) or an ellipsoid (or other shapes). The adjustment structure has anisotropic characteristics, and the longest central axis of the adjustment structure can be referred to as a long axis, and the shortest central axis can be referred to as a short axis. The adjustment structure can be in a regular shape or an irregular shape, which is not limited in the present application.

[0017] Optionally, the first and second groups of adjustment structures comprise at least two adjustment structures arranged in sequence along the first direction, the at least two adjustment structures increasing or decreasing the phase delay of the first light beam before passing through the adjustment layer. In the present application, the variation range of the phase delay of the first light beam before passing through the adjustment layer by the at least two adjustment structures can be [0, 2π], optionally, the variation range can also not be [0, 2π], such as the variation range being [0, π], [0, 3π / 2] or [π, 2π], etc. It should be noted that the phase delay of the first light beam before passing through the adjustment layer by the at least two adjustment structures can be linearly increased or decreased, or can be non-linearly increased or decreased. Compared with the non-linearly increased or decreased phase delay of the first light beam before passing through the adjustment layer by the at least two adjustment structures, the energy of the light emitted from the polarization-independent device is higher when the phase delay of the first light beam before passing through the adjustment layer by the at least two adjustment structures is linearly increased or decreased.

[0018] When the phase delay of the first light beam before passing through the adjustment layer by the at least two adjustment structures is increased or decreased, the phase delay of the first light beam before passing through the adjustment layer by the adjustment structures forms a phase gradient in the first direction. The phase gradient can change the phase of the light, thereby achieving the second phase adjustment of the first light beam before passing through the adjustment layer. For example, sinθ = P / K. Wherein, θ = α - β, α represents the adjustment angle of the propagation direction of the first light beam before passing through the liquid crystal layer by the polarization-independent device to the side of the liquid crystal layer away from the adjustment layer; β represents the adjustment angle of the propagation direction of the first light beam before passing through the liquid crystal layer by the part of the polarization-independent device other than the adjustment layer. In other words, θ can be regarded as the change angle of the adjustment angle of the propagation direction of the first light beam before passing through the liquid crystal layer by the polarization-independent device to the side of the liquid crystal layer away from the adjustment layer after introducing the adjustment layer. sinθ represents the sine of θ, P represents the phase gradient, and K represents the optical wave vector.

[0019] Further, the polarization-independent device can also satisfy at least one of the following conditions: the number of adjustment structures in the first and second groups of adjustment structures is the same; the same order of adjustment structures in the first and second groups of adjustment structures has the same size; and for one of the first and second groups of adjustment structures, when the number of adjustment structures in the adjustment structure group is greater than 1, the sizes of different adjustment structures in the adjustment structure group are different. In the present application, the polarization-independent device simultaneously satisfies these conditions is taken as an example.

[0020] It can be understood that the number of adjustment structures in the first adjustment structure group and the second adjustment structure group can also be different; and / or, the adjustment structures of the same order in the first adjustment structure group and the second adjustment structure group can also have different sizes; and / or, for one of the first adjustment structure group and the second adjustment structure group, when the number of adjustment structures in the adjustment structure group is greater than 1, the sizes of different adjustment structures in the adjustment structure group can also be the same. In addition, the material of the adjustment structure can include gold, silver, aluminum, silicon, gallium nitride, titanium oxide, etc. The adjustment structure can include one material, or can include multiple materials. Moreover, the refractive index of the material of the outer layer of the adjustment structure in the first adjustment structure group can be the same as or different from the refractive index of the material of the outer layer of the adjustment structure in the second adjustment structure group.

[0021] Further, for one of the first adjustment structure group and the second adjustment structure group, the number of adjustment structures in the adjustment structure group can be 1, or can be greater than 1.

[0022] Optionally, when the plurality of adjustment structures includes some adjustment structures arranged along a direction perpendicular to the first direction, different adjustment structures among these adjustment structures have the same phase delay amount of the first light beam before passing through the adjustment layer. It can be understood that the phase delay amount of the first light beam of different adjustment structures arranged along the direction can also be different. The plurality of adjustment structures can also not include different adjustment structures arranged along a direction perpendicular to the first direction, for example, the plurality of adjustment structures only includes a row of adjustment structures arranged along the first direction, which is not limited in the present application.

[0023] Optionally, the included angle between the longest central axis of the adjustment structure and the long axis direction of the liquid crystal in the liquid crystal layer when the electric field is not applied is in the range of [40 degrees, 50 degrees], and the difference between the phase delay amounts of the first light beam before passing through the adjustment layer in the extension direction of the longest central axis of the adjustment structure and in the direction perpendicular to the extension direction (two orthogonal directions) is in the range of [0.9π, 1.1π]. At this time, the adjustment structure can realize the above-mentioned polarization direction adjustment of the first light beam. For example, the difference between the phase delay amounts can be π, and / or the included angle can be 45 degrees.

[0024] In the present application, the material, size, shape, arrangement mode (related to the longest central axis of the adjustment structure, arrangement order, distance between the centers of adjacent adjustment structures, etc.) of the adjustment structure can be designed to make the adjustment layer have the functions of second phase adjustment and polarization direction adjustment.

[0025] Further, no matter how the adjustment structure is arranged, the maximum length of the adjustment structure can be smaller than the wavelength of the incident light, which can be referred to as a subwavelength structure. Generally, the wavelength of light is a nanometer-level length, and thus, when the maximum length of the adjustment structure is smaller than the wavelength of light, the size of the adjustment structure is small, the thickness of the adjustment layer in which the adjustment structure is located is small, the thickness of the entire polarization-independent device is small, the driving voltage for driving the liquid crystal layer is small, and the power consumption for deflecting the liquid crystal layer is small. In this application, the maximum length of the adjustment structure is taken as an example of a nanometer-level length, and alternatively, the maximum length of the adjustment structure can also be a micrometer-level length, and the like, which is not limited in this application. When the adjustment structure has a micrometer-level size or a nanometer-level size, the adjustment structure can be referred to as a micro-nano structure.

[0026] Alternatively, the part of the adjustment layer for performing the second phase adjustment and the polarization direction adjustment can include a plurality of sub-layers, and each sub-layer includes the plurality of adjustment structures.

[0027] It should be noted that, in the above content, the adjustment layer uses a plurality of adjustment structures to perform the above-mentioned second phase adjustment and polarization direction adjustment, and it can be understood that when the adjustment layer also needs to perform other adjustments (such as the third phase adjustment that the above-mentioned second light beam can pass through) in addition to the above-mentioned second phase adjustment and polarization direction adjustment, the other adjustments can also be implemented by using a plurality of adjustment structures. At least one of the parameters such as the material, size, shape, and arrangement of the adjustment structure can be designed according to the function that the plurality of adjustment structures need to have.

[0028] Further, the liquid crystal layer can be deflected under the action of an electric field to adjust the phase of the light component having the first polarization direction, and the electric field can be applied to the liquid crystal layer by an electric field applying assembly. The electric field applying assembly can be located inside the polarization-independent device, or located outside the polarization-independent device, or part of the electric field applying assembly is located inside the polarization-independent device, and the other part is located outside the polarization-independent device.

[0029] For example, when the adjustment layer includes the functional layer and the reflective layer, the polarization-independent device can further include a transparent electrode layer and a liquid crystal driving circuit, the transparent electrode layer is located on the side of the liquid crystal layer away from the reflective layer, and the liquid crystal driving circuit is located on the side of the reflective layer away from the liquid crystal layer; the reflective layer is conductive; and the liquid crystal driving circuit is configured to apply a voltage to the transparent electrode layer and the reflective layer to form an electric field between the transparent electrode layer and the reflective layer. The liquid crystal in the liquid crystal layer can be deflected under the action of the electric field.

[0030] Further, the polarization independent device further comprises other structures, for example, the polarization independent device further comprises: a first alignment layer, a second alignment layer, a planarization layer, a passivation layer. In the polarization independent device, the transparent electrode layer, the first alignment layer, the liquid crystal layer, the second alignment layer, the planarization layer, the functional layer, the passivation layer, the reflective layer and the liquid crystal driving circuit are sequentially stacked. The first alignment layer and the second alignment layer are used for aligning the liquid crystal layer, so that the long axis directions of the liquid crystals in the liquid crystal layer are parallel (or tend to be parallel) to each other when no electric field is applied. The planarization layer plays a role of planarizing the surface of the functional layer, thereby supporting the subsequent packaging process of the liquid crystal layer.

[0031] In a second aspect, a light adjustment device is provided, which comprises the polarization independent device according to any one of the first aspect, and is used for adjusting the phase of light by using the polarization independent device. For example, the light adjustment device can be any device capable of adjusting the phase of light, such as a WSS, a reconfigurable optical add / drop multiplexer (ROADM) in which the WSS is located, a spatial light modulator, a display device, etc.

[0032] Optionally, the light adjustment device further comprises: a plurality of ports (including an input port and a plurality of output ports). The input port is used for providing light to the side of the liquid crystal layer in the polarization independent device; the polarization independent device is used for shooting the first light beam (the first light beam that has passed through the liquid crystal layer and is shot out of the liquid crystal layer from the side of the adjustment layer far away from the liquid crystal layer) after passing through the liquid crystal layer to the output port, and shooting the second light beam (the second light beam that has passed through the liquid crystal layer and is shot out of the liquid crystal layer from the side of the adjustment layer far away from the liquid crystal layer) after passing through the liquid crystal layer to a direction deviating from the output port. In other words, when the light adjustment device comprises the input port and the plurality of output ports, the positions of the output ports can be designed so that the light beams shot from the polarization independent device to the output ports have undergone the first phase adjustment, the second phase adjustment and the polarization direction adjustment in the polarization independent device, while the light beams that have not undergone the second phase adjustment and the polarization direction adjustment in the polarization independent device will not be shot to the output ports, so that the light beams that have not undergone the polarization direction adjustment by the adjustment layer can be prevented from being shot to the output ports and causing port crosstalk.

[0033] Further, according to the first aspect, the light component of the first polarization direction is located in the first plane before and after passing through the liquid crystal layer, and the first light beam and the second light beam are located in the second plane when being shot from the adjustment layer to the liquid crystal layer. The first plane and the second plane are coplanar, or the included angle between the first plane and the second plane is greater than zero.

[0034] In the first implementation, when the first plane and the second plane are coplanar, the input port and the plurality of output ports are arranged in sequence along a direction parallel to the first plane and the polarization-independent device, and the polarization-independent device is perpendicular to the first plane. It should be noted that the polarization-independent device is a device obtained by stacking a plurality of films, and the polarization-independent device being perpendicular to the first plane means that the plurality of films are all perpendicular to the first plane, and the stacking direction of the plurality of films is parallel to the first plane. At this time, the plurality of output ports are located on one side of the input port. In the incident light, the light beams that have undergone the first phase adjustment, the second phase adjustment and the polarization direction adjustment in the polarization-independent device will be incident on the output ports on the side of the input port, and the light beams that have not undergone the second phase adjustment and the polarization direction adjustment in the polarization-independent device will be incident on the input port or the side of the input port away from the output ports.

[0035] In the second implementation, when the angle between the first plane and the second plane is greater than zero (for example, the angle is 90 degrees), the plurality of ports are arranged in sequence along a direction parallel to the first plane and a reference plane, the reference plane being perpendicular to the first plane; and the polarization-independent device is rotated by -θ / 2 with respect to the reference plane; θ = α - β, α representing an adjustment angle of the polarization-independent device to the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjustment layer, and β representing an adjustment angle of the polarization-independent device to the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjustment layer, except for the adjustment layer.

[0036] In the second implementation, the adjustment of the polarization-independent device to the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjustment layer is related to three factors, which include: (1) the first phase adjustment of the liquid crystal layer to the light component of the first polarization direction under the action of the electric field; (2) the second phase adjustment of the adjustment layer; and (3) the rotation angle of the polarization-independent device with respect to the reference plane. The adjustment of the polarization-independent device to the propagation direction of the second light beam before sequentially passing through the liquid crystal layer and the adjustment layer is related to factors (1) and (3).

[0037] When the liquid crystal layer is not applied with the electric field, the adjustment of the propagation direction of the first light beam before passing through the liquid crystal layer and the adjusting layer in sequence by the polarization-independent device is related to factors (2) and (3). Factor (2) will make the change angle of the propagation direction θ, and factor (3) will make the change angle of the propagation direction -θ, so factors (2) and (3) make the change angle of the propagation direction offset each other. When the liquid crystal layer is applied with the electric field, on the one hand, for the first light beam before passing through the liquid crystal layer and the adjusting layer in sequence, since factors (2) and (3) offset each other, the propagation direction of the light beam when it is emitted from the polarization-independent device is related to factor (1), and the light beam can be transmitted to the out port under the action of the liquid crystal layer. On the other hand, for the second light beam before passing through the liquid crystal layer and the adjusting layer in sequence, the propagation direction of the light beam when it is emitted from the polarization-independent device is related to factors (1) and (3), and the light beam can be transmitted to any side of the plurality of ports in the dispersion direction under the influence of factors (1) and (3), thereby avoiding the light beam without polarization direction adjustment from being emitted to the out port.

[0038] Further, the light adjusting device can further include other structures, for example, the light adjusting device further includes a lens (such as a convex lens) located between the polarization-independent device and the plurality of ports.

[0039] In a third aspect, a light network system is provided, and the light network system includes the light adjusting device according to any one of the designs in the second aspect. For example, the light network system uses light for communication, and the light adjusting device can adjust the phase of the light by using the polarization-independent device therein, so as to realize port exchange of the light.

[0040] The effects of the second aspect and the third aspect can refer to the effects of the corresponding designs in the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A structural schematic diagram of a polarization-independent device provided by an embodiment of the present application;

[0042] Figure 2 A transmission schematic diagram of a light component provided by an embodiment of the present application;

[0043] Figure 3 A polarization direction schematic diagram of a first light component provided by an embodiment of the present application;

[0044] Figure 4 A polarization direction schematic diagram of a second light component provided by an embodiment of the present application;

[0045] Figure 5 A propagation direction schematic diagram of a first light component provided by an embodiment of the present application;

[0046] Figure 6 A structure schematic diagram of a WSS provided for an embodiment of the present application;

[0047] Figure 7 A structure schematic diagram of another polarization independent device provided for an embodiment of the present application;

[0048] Figure 8 A polarization schematic diagram of a liquid crystal provided for an embodiment of the present application;

[0049] Figure 9 A structure schematic diagram of another polarization independent device provided for an embodiment of the present application;

[0050] Figure 10 A transmission schematic diagram of an optical component in a WSS provided for an embodiment of the present application;

[0051] Figure 11 A transmission schematic diagram of an optical component in another WSS provided for an embodiment of the present application;

[0052] Figure 12 A propagation path schematic diagram of an optical component provided for an embodiment of the present application;

[0053] Figure 13 A structure schematic diagram of another polarization independent device provided for an embodiment of the present application;

[0054] Figure 14 A distribution schematic diagram of a plurality of adjustment structures provided for an embodiment of the present application;

[0055] Figure 15 A distribution schematic diagram of another plurality of adjustment structures provided for an embodiment of the present application;

[0056] Figure 16 A distribution schematic diagram of another plurality of adjustment structures provided for an embodiment of the present application;

[0057] Figure 17 A distribution schematic diagram of another plurality of adjustment structures provided for an embodiment of the present application;

[0058] Figure 18 A distribution schematic diagram of another plurality of adjustment structures provided for an embodiment of the present application;

[0059] Figure 19 A distribution schematic diagram of another plurality of adjustment structures provided for an embodiment of the present application;

[0060] Figure 20 A structure schematic diagram of another polarization independent device provided for an embodiment of the present application;

[0061] Figure 21This is a schematic diagram of another polarization-independent device provided in an embodiment of this application;

[0062] Figure 22 This is a schematic diagram of another WSS structure provided in an embodiment of this application. Detailed Implementation

[0063] To make the principles and technical solutions of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0064] Polarization-independent devices are a common type of device in the optical field, such as... Figure 1 As shown, the polarization-independent device includes a superimposed liquid crystal layer 01 and an adjustment layer 02. This polarization-independent device is also called liquid crystal on silicon (LCoS). The liquid crystal in the liquid crystal layer 01 can be a nematic liquid crystal or a ferroelectric liquid crystal, etc. In this embodiment, a nematic liquid crystal is used as an example. The adjustment layer 02 may include a half-wave plate (HWP) 02 and a reflective layer 022, with the reflective surface of the reflective layer 022 facing the HWP 021. After light enters the liquid crystal layer 01 from the side away from the adjustment layer 02, it will travel along the path of liquid crystal layer 01, HWP 021, reflective layer 022, HWP 021, and back to liquid crystal layer 01.

[0065] like Figure 2 As shown, light incident from the side of liquid crystal layer 01 away from adjustment layer 02 includes a first light component having a first polarization direction P and a second light component having a second polarization direction S. The first polarization direction P is perpendicular to the second polarization direction S. When the incident light is polarized light, the first light component or the second light component may be zero. In this case, the light incident from the side of liquid crystal layer 01 away from adjustment layer 02 includes either the first light component or the second light component. Optionally, in this embodiment, the first polarization direction P is parallel to the long axis direction of the liquid crystal in liquid crystal layer 01 when no electric field is applied. Optionally, the first polarization direction P may not be parallel to this long axis direction. This embodiment does not limit the first polarization direction.

[0066] Please continue to refer to this. Figure 2 The liquid crystal in liquid crystal layer 01 can be deflected under the action of an electric field (e.g., Figure 2As shown in FIG. 2, the liquid crystal layer 01 is applied with an electric field, so that the liquid crystal layer 01 adjusts the phase of the light component with the first polarization direction P passing through the liquid crystal layer 01, and does not adjust the phase of the light component without the first polarization direction P passing through the liquid crystal layer 01. After the phase adjustment, the propagation direction of the light component is changed. The liquid crystal layer 01 applied with the electric field is referred to as the liquid crystal layer 01 loaded with a phase pattern. Since the first light component has the first polarization direction P, the liquid crystal layer 01 adjusts the phase of the first light component passing through the liquid crystal layer 01 under the action of the electric field, so that the propagation direction of the first light component is changed. Since the second polarization direction S of the second light component is different from the first polarization direction P, the liquid crystal layer 01 does not adjust the phase of the second light component passing through the liquid crystal layer 01 under the action of the electric field, so that the propagation direction of the second light component remains unchanged.

[0067] The first light component and the second light component passing through the liquid crystal layer 01 reach the adjustment layer 02, and the adjustment layer 02 adjusts the polarization direction of the light components and transmits the light components with the adjusted polarization direction to the liquid crystal layer 01. The polarization direction of the first light component with the adjusted polarization direction is changed from the first polarization direction P to the second polarization direction S, and the polarization direction of the second light component with the adjusted polarization direction is changed from the second polarization direction S to the first polarization direction P. For example, the adjustment layer 02 includes the HWP 021 and a reflecting layer 022. The first light component and the second light component passing through the liquid crystal layer 01 reach the HWP 021, the HWP 021 adjusts the polarization direction of the first light component and the second light component, and the light components are reflected by the reflecting layer 022 and then emitted from the HWP 021 to the liquid crystal layer 01. As shown in FIG. 3, in the case where the liquid crystal layer 01 is not applied with an electric field, the first light component passing through the liquid crystal layer 01 has the first polarization direction P when emitted from the liquid crystal layer 01 to the HWP 021, but the first light component passing through the adjustment layer 02 has the second polarization direction S perpendicular to the first polarization direction P when emitted from the HWP 021 to the liquid crystal layer 01. Figure 3 As shown in FIG. 4, in the case where the liquid crystal layer 01 is not applied with an electric field, the second light component passing through the liquid crystal layer 01 has the second polarization direction S when emitted from the liquid crystal layer 01 to the HWP 021, but the second light component passing through the adjustment layer 02 has the first polarization direction P perpendicular to the second polarization direction S when emitted from the HWP 021 to the liquid crystal layer 01. Figure 4 As shown in FIG. 4, in the case where the liquid crystal layer 01 is not applied with an electric field, the second light component passing through the liquid crystal layer 01 has the second polarization direction S when emitted from the liquid crystal layer 01 to the HWP 021, but the second light component passing through the adjustment layer 02 has the first polarization direction P perpendicular to the second polarization direction S when emitted from the HWP 021 to the liquid crystal layer 01.

[0068] When the first light component and the second light component passing through the adjusting layer 02 reach the liquid crystal layer 01 again, the polarization direction of the first light component passing through the adjusting layer 02 is the second polarization direction S, and the polarization direction of the second light component passing through the adjusting layer 02 is the first polarization direction P. Therefore, the liquid crystal layer 01 adjusts the phase of the second light component passing through the adjusting layer 02 under the action of the electric field, but does not adjust the phase of the first light component passing through the adjusting layer 02 (this process is not shown in the figure).

[0069] It can be seen that the polarization directions of the first light component and the second light component are different, but the polarization-independent device can adjust the phase of the two light components once by the liquid crystal layer 01. Therefore, the polarization direction does not affect the phase adjustment, and thus the polarization direction does not affect the propagation direction of the light component emitted from the polarization-independent device.

[0070] However, due to the manufacturing defects of the adjusting layer 02 (such as the HWP 021 in the adjusting layer 02), the adjusting layer 02 cannot adjust the polarization direction of all the incident light components. If the adjusting layer 02 does not adjust the polarization direction of part of the first light component passing through the liquid crystal layer 01, this part of the first light component passing through the adjusting layer 02 still has the first polarization direction P when it reaches the liquid crystal layer 01. Since the liquid crystal in the liquid crystal layer 01 can be deflected under the action of the electric field to adjust the phase of the light component with the first polarization direction P, this part of the first light component will be adjusted in phase again by the liquid crystal layer 01 when it reaches the liquid crystal layer 01 again. It can be seen that this part of the first light component will be adjusted twice in the propagation direction by the liquid crystal layer 02. For example, as shown in Figure 5 , it is assumed that the first light component has a propagation direction 1 after being adjusted once in phase by the liquid crystal layer 01 in the polarization-independent device, and the first light component has a propagation direction 2 after being adjusted twice in phase by the liquid crystal layer 01 in the polarization-independent device, and the propagation direction 1 and the propagation direction 2 are different.

[0071] Further, the polarization-independent device can be applied in an optical adjustment apparatus, such as a WSS, a ROADM in which the WSS is located, a spatial light modulator, a display device, etc. If the first light component is adjusted twice in phase in the polarization-independent device, it will affect the normal operation of the optical adjustment apparatus.

[0072] For example, in a WSS, the WSS includes an input port and a plurality of output ports (both the input port and the output port can be the port of an optical fiber) in addition to the polarization-independent device. If some first light components are adjusted twice in phase in the polarization-independent device, these first light components that need to be emitted to a certain output port may be emitted to other output ports, causing crosstalk between the ports. For example, Figure 6As shown, the WSS includes: an input port, a plurality of output ports, a lens, and a polarization independent device. Among the light emitted from the polarization independent device, the first light component (having the second polarization direction S) that has undergone one phase adjustment in the polarization independent device is emitted to the output port 1, and the first light component (having the first polarization direction P) that has undergone two phase adjustments in the polarization independent device is emitted to the output port 2, so that there is crosstalk between the output ports 1 and 2.

[0073] For example, in a spatial light modulator, if there is a first light component that has undergone two phase adjustments in the polarization independent device, effective modulation of the first light component cannot be achieved. In a display device, if there is a first light component that has undergone two phase adjustments in the polarization independent device, the display effect of the display device will be affected.

[0074] In addition, the above-mentioned HWP 021 in the adjustment layer 02 is usually made of cured liquid crystal material or micro-nano material with birefringence characteristics. When the HWP 021 is made of cured liquid crystal material, a micron-thick liquid crystal material is needed to make the HWP, resulting in a thick HWP, a thick polarization independent device, and limiting the application scenarios of the polarization independent device.

[0075] In addition, as shown in Figure 7 , the polarization independent device usually further includes a transparent electrode 03 and a liquid crystal driving circuit 04 (such as a silicon-based liquid crystal driving circuit), the transparent electrode 03 is located on the side of the liquid crystal layer 01 away from the adjustment layer 02, and the liquid crystal driving circuit 04 is located on the side of the adjustment layer 02 away from the liquid crystal layer 01. The reflective layer 022 is conductive, and the liquid crystal driving circuit 04 is connected with the transparent electrode 03 and the reflective layer 022. The liquid crystal driving circuit 04 is used to apply a voltage to the transparent electrode 03 and the reflective layer 022 to form an electric field between the transparent electrode 03 and the reflective layer 022, and the liquid crystal in the liquid crystal layer 01 deflects under the action of the electric field, so that the liquid crystal layer 01 adjusts the phase of the light component of the first polarization direction P under the action of the electric field. For example, when the electric field is formed between the transparent electrode 03 and the reflective layer 022, Figure 7 , the deflection of the liquid crystal in the liquid crystal layer 01 can be as shown in Figure 8 . Please refer to Figure 8 , the liquid crystal layer 01 can form a holographic blazed grating under the action of the electric field to adjust the phase of the light component of the first polarization direction P.

[0076] In the polarization independent device, when the HWP is thick, the distance between the transparent electrode and the reflective layer is large. At this time, if an electric field needs to be applied to the liquid crystal layer through the transparent electrode and the reflective layer, the liquid crystal driving circuit needs to apply a higher driving voltage to the transparent electrode and the reflective layer, resulting in high power consumption of the polarization independent device and limiting the application scenarios of the polarization independent device.

[0077] This application provides a polarization-independent device that enables polarization-adjusted light and unadjusted light to have different propagation directions, thereby spatially isolating these two types of light and preventing the unadjusted light from affecting the light adjustment device. Furthermore, the polarization-independent device provided in this application has a small film thickness for adjusting the polarization direction, eliminating the need for the liquid crystal driving circuit to apply a high driving voltage to the transparent electrode and reflective layer, thus resulting in low power consumption.

[0078] For example, Figure 9 This is a schematic diagram of the structure of a polarization-independent device provided in an embodiment of this application, as shown below. Figure 9 As shown, the polarization-independent device includes: a superimposed liquid crystal layer 11 and an adjustment layer 12.

[0079] The liquid crystal layer 11 is used to perform a first phase adjustment on the light component passing through the first polarization direction under the action of an electric field. The function of the liquid crystal layer 11 can be referred to the function of the liquid crystal layer 01 described above, and will not be repeated here in the embodiments of this application. For example, the liquid crystal layer 11 can receive light incident on the side of the liquid crystal layer 11 away from the adjustment layer 12, the light having light components with a first polarization direction and a second polarization direction, the first polarization direction being perpendicular to the second polarization direction; the liquid crystal layer 11 can perform a first phase adjustment on the light component with the first polarization direction under the action of an electric field, but may not perform a first phase adjustment on the light component with the second polarization direction.

[0080] The adjustment layer 12 is used to generate a first beam and a second beam based on the light component of the light incident through the liquid crystal layer 11 with a first polarization direction, and to transmit the first beam and the second beam to the liquid crystal layer 11. The first beam undergoes a second phase adjustment and polarization direction adjustment in the adjustment layer 12, while the second beam does not undergo the second phase adjustment and polarization direction adjustment in the adjustment layer 12. The polarization direction adjustment is used to change the polarization direction by 90 degrees; therefore, the polarization direction of the first beam is perpendicular to the polarization direction of the first beam before polarization direction adjustment (the polarization direction of the first beam before passing through the adjustment layer). The first beam and the second beam have different propagation directions after passing through the liquid crystal layer 11; that is, the first beam and the second beam have different propagation directions after being incident from the adjustment layer 12 onto the liquid crystal layer 11 and passing through the liquid crystal layer 11.

[0081] It can be seen that, for the light component of the first polarization direction entering the adjusting layer 12, the adjusting layer can perform the second phase adjustment and the polarization direction adjustment on part of the light beams in the light component, so as to obtain a first light beam and a second light beam, wherein the first light beam is the light beam after the second phase adjustment and the polarization direction adjustment, and the second light beam is the light beam without the second phase adjustment and the polarization direction adjustment. Among the first light beam and the second light beam, the light beam after the polarization direction adjustment also undergoes the second phase adjustment, and the light beam without the polarization direction adjustment also does not undergo the second phase adjustment. Therefore, the first light beam and the second light beam undergo different phase adjustments, and the first light beam and the second light beam have different propagation directions when being emitted from the adjusting layer 12 to the liquid crystal layer 11, so as to realize the separation of the first light beam and the second light beam.

[0082] Compared with Figure 1 the polarization-independent device shown in the figure, Figure 9 The adjusting layer 12 in the polarization-independent device not only can perform the polarization direction adjustment, but also can perform the second phase adjustment. At this time, the components in the polarization-independent device that can perform the phase adjustment on the light not only include the liquid crystal layer 11 for performing the first phase adjustment, but also include the adjusting layer 12 for performing the second phase adjustment. In this way, the propagation direction of the light after the polarization direction adjustment when being emitted from the polarization-independent device is not only related to the first phase adjustment of the liquid crystal layer 11, but also related to the second phase adjustment of the adjusting layer 12. The propagation direction of the light without the polarization direction adjustment when being emitted from the polarization-independent device is related to the first phase adjustment of the liquid crystal layer 11, but is not related to the second phase adjustment of the adjusting layer 12. It can be seen that the propagation direction of the light after the polarization direction adjustment when being emitted from the polarization-independent device has two control points of the liquid crystal layer 11 and the adjusting layer 12, and the propagation direction of the light without the polarization direction adjustment when being emitted from the polarization-independent device has one control point of the liquid crystal layer 11. Therefore, the light after the polarization direction adjustment and the light without the polarization direction adjustment are subjected to different phase adjustments in the polarization-independent device, so that the propagation directions of the light after the polarization direction adjustment and the light without the polarization direction adjustment when being emitted from the liquid crystal layer 11 away from the adjusting layer 12 are different.

[0083] In summary, in the polarization-independent device provided in this application embodiment, the adjustment layer can transmit a first beam that has undergone second phase adjustment and polarization direction adjustment, and a second beam that has not undergone second phase adjustment and polarization direction adjustment, to the liquid crystal layer based on the light component of the first polarization direction incident on the liquid crystal layer; furthermore, the propagation directions of the first beam and the second beam are different after passing through the liquid crystal layer. It is evident that the light with polarization direction adjustment and the light without polarization direction adjustment undergo different adjustments in the polarization-independent device, thereby causing the light with polarization direction adjustment and the light without polarization direction adjustment to have different propagation directions when emitted from the polarization-independent device. This spatially isolates the two types of light, preventing the influence of the light component of the first polarization direction without polarization direction adjustment on the light adjustment device.

[0084] For example, when the light adjustment device is WSS, such as Figure 10 As shown, taking the light component with the first polarization direction P emitted from the inlet port to the polarization-independent device as an example, it can be designed that the first beam obtained by the adjustment layer based on this light component passing through the liquid crystal layer is directed towards the outlet port N-1 (N>1) after exiting the polarization-independent device; while the second beam obtained by the adjustment layer based on this light component passing through the liquid crystal layer is directed away from the outlet port after exiting the polarization-independent device. This avoids crosstalk between ports caused by the second beam, which has not undergone polarization direction adjustment, being directed towards the outlet port after exiting the polarization-independent device.

[0085] The phase of the first beam after exiting the polarization-independent device is related not only to the liquid crystal layer 11 but also to the adjustment layer 12, while the phase of the second beam after exiting the polarization-independent device is related not only to the liquid crystal layer 11 but also to the adjustment layer 12. Assuming no electric field is applied to the nematic liquid crystal, such as... Figure 11 As shown, under the action of the second phase adjustment of the adjustment layer 12, the first beam (after polarization direction adjustment and second phase adjustment) emitted from the polarization-independent device will be directed towards port N after exiting the polarization-independent device, while the second beam (without polarization direction adjustment and second phase adjustment) will return to the input port after exiting the polarization-independent device. When an electric field is applied to the liquid crystal layer, the liquid crystal layer can make... Figure 11 The light emitted from the polarization-independent device is deflected upwards by a port distance. This allows the light emitted from the polarization-independent device to have a polarization-independent characteristic similar to... Figure 10 The transmission status is shown.

[0086] It can be understood that the light component incident into the liquid crystal layer from the side of the liquid crystal layer away from the adjusting layer can include the light component of the first polarization direction and the light component of another polarization direction (such as a second polarization direction perpendicular to the first polarization direction) different from the first polarization direction. The liquid crystal layer can be configured to not perform the first phase adjustment on the light component of the other polarization direction under the action of the electric field. After the light component of the other polarization direction passes through the liquid crystal layer and is incident into the adjusting layer, the adjusting layer can be configured to obtain the third light beam and the fourth light beam based on the light component of the other polarization direction incident into the adjusting layer and passing through the liquid crystal layer, and transmit the third light beam and the fourth light beam to the liquid crystal layer. The third light beam passes through the second phase adjustment and the polarization direction adjustment in the adjusting layer, but the fourth light beam does not pass through the second phase adjustment and the polarization direction adjustment in the adjusting layer. The polarization direction adjustment is configured to change the polarization direction by 90 degrees, so that the polarization direction of the third light beam is perpendicular to the polarization direction of the third light beam before the polarization direction adjustment (the polarization direction of the third light beam before passing through the adjusting layer). The propagation directions of the third light beam and the fourth light beam after passing through the liquid crystal layer are different. In this way, the influence of the light component of each polarization direction that does not pass through the polarization direction adjustment on the light adjusting device can also be avoided.

[0087] In other words, the light component of at least one polarization direction is incident into the liquid crystal layer from the side of the liquid crystal layer away from the adjusting layer. The liquid crystal layer is configured to perform the first phase adjustment on the light component of the first polarization direction in the light component of the at least one polarization direction under the action of the electric field. For the light component of each polarization direction in the at least one polarization direction incident into the adjusting layer and passing through the liquid crystal layer, the adjusting layer can obtain two light beams based on the light component and transmit the two light beams to the liquid crystal layer. One of the two light beams passes through the second phase adjustment and the polarization direction adjustment in the adjusting layer, and the other light beam does not pass through the second phase adjustment and the polarization direction adjustment in the adjusting layer. The polarization direction adjustment is configured to change the polarization direction by 90 degrees. The propagation directions of the two light beams after passing through the liquid crystal layer are different. In this way, the influence of the light component of each polarization direction that does not pass through the polarization direction adjustment on the light adjusting device can also be avoided.

[0088] Optionally, when the at least one polarization direction includes another polarization direction in addition to the first polarization direction, the adjusting layer can also not be configured to transmit the third light beam and the fourth light beam to the liquid crystal layer based on the light component of the other polarization direction incident into the adjusting layer and passing through the liquid crystal layer, which is not limited in the present application.

[0089] The adjustment layer obtains a related interpretation of the third beam based on the light components of each polarization direction incident through the liquid crystal layer, which can be referred to as the related interpretation of the adjustment layer obtaining the first beam based on the light components of the first polarization direction incident through the liquid crystal layer; the adjustment layer obtains a related interpretation of the fourth beam based on the light components of each polarization direction incident through the liquid crystal layer, which can be referred to as the related interpretation of the adjustment layer obtaining the second beam based on the light components of the first polarization direction incident through the liquid crystal layer; this application will not elaborate further here.

[0090] Furthermore, the two types of light beams transmitted from the adjustment layer to the liquid crystal layer undergo different phase adjustments within the adjustment layer. Optionally, the light beam that has not undergone the second phase adjustment and polarization direction adjustment may also undergo other adjustments in the adjustment layer besides the second phase adjustment and polarization direction adjustment. For example, the light beam may undergo a third phase adjustment in the adjustment layer, different from the second phase adjustment; this application does not limit this. For example, the aforementioned second light beam and / or fourth light beam may undergo a third phase adjustment in the adjustment layer, different from the second phase adjustment; this application does not limit this.

[0091] Furthermore, the liquid crystal layer adjusts the propagation direction of the light component in the first polarization direction using a first phase adjustment method, and the adjustment layer adjusts the propagation direction of the light component in the first polarization direction using a second phase adjustment method. During this process, the amplitude of the light is not adjusted, thus minimizing light energy loss.

[0092] Furthermore, the propagation path of the light component in the first polarization direction before and after passing through the liquid crystal layer 11 (e.g.) Figure 12 Both propagation path 1 and propagation path 2 in the image are located in the first plane (e.g., ...). Figure 12 (as shown in the paper), the first beam and the second beam propagate along the path from the adjustment layer 12 to the liquid crystal layer 11 (e.g., the paper surface), the propagation path of the first beam and the second beam. Figure 12 Propagation paths 3 and 4 in the image are both located in the second plane (e.g., ...). Figure 12 (The propagation paths of the third and fourth beams from the adjustment layer 12 to the liquid crystal layer 11 can also both be located on the second plane). Figure 12 Taking the coplanarity of the first and second planes as an example. Alternatively, the angle between the first and second planes can be greater than zero degrees. For example, the angle can be 90 degrees, or the angle can be less than 90 degrees (such as 80 degrees, 85 degrees, etc.).

[0093] Furthermore, the adjustment layer 12 in the polarization-independent device provided in this application embodiment can be implemented in various ways.

[0094] For example, such as Figure 13As shown, the adjustment layer 12 can include a functional layer 121 and a reflective layer 122 stacked in sequence in a direction away from the liquid crystal layer 11, and a reflecting surface of the reflective layer 122 faces the functional layer 121; the second phase adjustment and the polarization direction adjustment occur in the functional layer 121. For the light component incident from the side of the liquid crystal layer 11 away from the adjustment layer 12, the light component transmits in sequence through the functional layer 121, the reflective layer 122, and the functional layer 121 again to the liquid crystal layer 11, and in this process, the light component of the first polarization direction passes through the functional layer 121 twice, and at this time, the second phase adjustment can include a first phase adjustment of the light component of the first polarization direction in the process of passing through the functional layer 121 for the first time, and a second phase adjustment of the light component of the first polarization direction in the process of passing through the functional layer 121 for the second time. The polarization direction adjustment can include that the light component of the first polarization direction changes from the first linear polarization to circular polarization in the process of passing through the functional layer 121 for the first time, and the light component of the first polarization direction changes from the circular polarization to the second linear polarization in the process of passing through the functional layer 121 for the second time, and the polarization direction of the first linear polarization is perpendicular to the polarization direction of the second linear polarization. The polarization direction adjustment of the light component of the first polarization direction by the functional layer 121 can refer to the polarization direction adjustment of the light component by the HWP 021 described above. The functional layer 121 can be used to realize the function of the HWP 021 described above.

[0095] Further, the part (such as the functional layer 121 described above) in the adjustment layer 12 for performing the second phase adjustment and the polarization direction adjustment can have multiple implementation manners.

[0096] Further, the part (such as the functional layer 121 described above) in the adjustment layer 12 for performing the second phase adjustment and the polarization direction adjustment can have multiple implementation manners.

[0097] For example, the part in the adjustment layer 12 for performing the second phase adjustment and the polarization direction adjustment can include multiple adjustment structures, which can form a metasurface structure or other structures different from the metasurface structure. The adjustment layer 12 can use the multiple adjustment structures to perform phase adjustment and polarization direction adjustment on light. The second phase adjustment and the polarization direction adjustment described above are related to at least one parameter of materials, sizes, shapes, and arrangement manners of the adjustment structures. When designing the part in the adjustment layer 12 for performing the second phase adjustment and the polarization direction adjustment, the at least one parameter can be set according to the function that the adjustment layer 12 needs to realize. The at least one parameter of materials, sizes, shapes, and arrangement manners of the adjustment structures can refer to the related description in subsequent embodiments.

[0098] For example, as shown in FIG. 2, the adjustment layer 12 can include a functional layer 121 and a reflective layer 122 stacked in sequence in a direction away from the liquid crystal layer 11, and a reflecting surface of the reflective layer 122 faces the functional layer 121; the second phase adjustment and the polarization direction adjustment occur in the functional layer 121. For the light component incident from the side of the liquid crystal layer 11 away from the adjustment layer 12, the light component transmits in sequence through the functional layer 121, the reflective layer 122, and the functional layer 121 again to the liquid crystal layer 11, and in this process, the light component of the first polarization direction passes through the functional layer 121 twice, and at this time, the second phase adjustment can include a first phase adjustment of the light component of the first polarization direction in the process of passing through the functional layer 121 for the first time, and a second phase adjustment of the light component of the first polarization direction in the process of passing through the functional layer 121 for the second time. The polarization direction adjustment can include that the light component of the first polarization direction changes from the first linear polarization to circular polarization in the process of passing through the functional layer 121 for the first time, and the light component of the first polarization direction changes from the circular polarization to the second linear polarization in the process of passing through the functional layer 121 for the second time, and the polarization direction of the first linear polarization is perpendicular to the polarization direction of the second linear polarization. The polarization direction adjustment of the light component of the first polarization direction by the functional layer 121 can refer to the polarization direction adjustment of the light component by the HWP 021 described above. The functional layer 121 can be used to realize the function of the HWP 021 described above. Figure 14As shown, the part of the adjusting layer 12 for performing the second phase adjustment and the polarization direction adjustment includes a plurality of adjusting structures 1211 arranged at intervals. The plurality of adjusting structures 1211 includes a first adjusting structure group 21 and a second adjusting structure group 22 arranged alternately along a first direction Q. Figure 14 In the embodiment, only one first adjusting structure group 21 and one second adjusting structure group 22 are shown. It can be understood that the plurality of adjusting structures 1211 can also include a plurality of first adjusting structure groups 21 and a plurality of second adjusting structure groups 22, and the first adjusting structure groups 21 and the second adjusting structure groups 22 are also arranged alternately along the first direction Q. The angle between the longest central axis L11 of the adjusting structure 1211 in the first adjusting structure group 21 and the longest central axis L12 of the adjusting structure 1211 in the second adjusting structure group 22 ranges from 80 degrees to 100 degrees. For example, Figure 14 In the embodiment, the longest central axis L11 of the adjusting structure 1211 in the first adjusting structure group 21 is perpendicular to the longest central axis L12 of the adjusting structure 1211 in the second adjusting structure group 22.

[0099] It should be noted that the adjusting structure 1211 has a central axis, and the adjusting structure 1211 can be symmetrical (completely symmetrical) or approximately symmetrical (not completely symmetrical) about the central axis. The adjusting structure 1211 can have one or more central axes, which are not limited in the embodiments of the present application. However, the one or more central axes have the longest central axis (such as L11 and L12 described above). For example, the adjusting structure 1211 can be in the shape of a rod (such as a cuboid, a cylinder, an elliptical cylinder) or an ellipsoid (or other shapes), Figure 14 In the embodiment, the adjusting structure 1211 is taken as a cuboid. The adjusting structure 1211 has the characteristic of anisotropy, and the longest central axis of the adjusting structure 1211 can be referred to as a long axis, and the shortest central axis can be referred to as a short axis. The adjusting structure 1211 can be in a regular shape or an irregular shape, which are not limited in the embodiments of the present application.

[0100] Optionally, the first adjusting structure group 21 and the second adjusting structure group 22 include at least two adjusting structures 1211 arranged in sequence along the first direction Q, and the at least two adjusting structures 1211 increase or decrease the phase delay amount of the first light beam (a kind of light beam emitted from the liquid crystal layer 11 to the adjusting layer 12) before passing through the adjusting layer 12. Figure 14 In the embodiment, the first direction Q is perpendicular to the long axis direction L2 of the liquid crystal in the liquid crystal layer 11 when no electric field is applied. The first direction Q can also be other directions, which are not limited in the embodiments of the present application. For example, Figure 14As shown, the first adjustment structure group 21 and the second adjustment structure group 22 include the at least two adjustment structures 1211, and in the direction from left to right, the at least two adjustment structures 1211 sequentially have phase retardation amounts of 0, π / 2, π, 3π / 2 to the first light beam before passing through the adjustment layer 12, and the phase retardation amounts sequentially increase. In the embodiment of the present application, the variation range of the phase retardation amounts of the at least two adjustment structures 1211 to the first light beam before passing through the adjustment layer 12 is [0, 2π], and optionally, the variation range can also not be [0, 2π], for example, the variation range is [0, π], [0, 3π / 2] or [π, 2π], etc. In addition, in the embodiment of the present application, the phase retardation amounts of the adjacent adjustment structures 1211 in the first direction Q to the first light beam before passing through the adjustment layer 12 differ by π / 2, and optionally, the difference between the phase retardation amounts of the adjacent adjustment structures 1211 in the first direction Q to the first light beam before passing through the adjustment layer 12 can also not be π / 2, for example, the difference between the phase retardation amounts of the adjacent adjustment structures 1211 in the first direction Q to the first light beam before passing through the adjustment layer 12 is π.

[0101] The phase retardation amounts of the at least two adjustment structures 1211 to the first light beam before passing through the adjustment layer 12 can be linearly increased or linearly decreased, or can be non-linearly increased or non-linearly decreased, Figure 14 In the embodiment of the present application, the phase retardation amounts of the at least two adjustment structures 1211 to the first light beam before passing through the adjustment layer 12 are linearly increased in the direction from left to right. Compared with the non-linearly increased or non-linearly decreased phase retardation amounts of the at least two adjustment structures 1211 to the first light beam before passing through the adjustment layer 12, when the phase retardation amounts of the at least two adjustment structures 1211 to the first light beam before passing through the adjustment layer 12 are linearly increased or linearly decreased, the energy of the light emitted from the polarization-independent device is higher.

[0102] When the phase retardation amounts of the at least two adjustment structures 1211 to the first light beam before passing through the adjustment layer 12 are increased or decreased, in the first direction Q, the phase retardation amounts of the adjustment structures 1211 to the first light beam before passing through the adjustment layer 12 form a phase gradient. The phase gradient can change the phase of the light, so as to achieve the second phase adjustment to the first light beam before passing through the adjustment layer 12. For example, sinθ = P / K. Wherein, θ = α - β, α represents the adjustment angle of the polarization-independent device to the propagation direction of the first light beam before passing through the liquid crystal layer 11, and β represents the adjustment angle of the part of the polarization-independent device other than the adjustment layer to the propagation direction of the first light beam before passing through the liquid crystal layer 11. In other words, θ can be regarded as the change angle of the adjustment angle of the polarization-independent device to the propagation direction of the first light beam before passing through the liquid crystal layer 11 after introducing the adjustment layer 12. sinθ represents the sine of θ, P represents the phase gradient, and K represents the optical wave vector.

[0103] Further, the polarization independent device can also satisfy at least one of the following conditions: the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 is the same; the adjustment structures 1211 in the same order in the first adjustment structure group 21 and the second adjustment structure group 22 have the same size; and for one of the first adjustment structure group 21 and the second adjustment structure group 22, when the number of adjustment structures 1211 in the adjustment structure group is greater than 1, the sizes of different adjustment structures in the adjustment structure group are different. Figure 14 Taking the polarization independent device satisfying these conditions at the same time as an example.

[0104] It can be understood that the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 can also be different; and / or, the adjustment structures 1211 in the same order in the first adjustment structure group 21 and the second adjustment structure group 22 can also have different sizes; and / or, for one of the first adjustment structure group 21 and the second adjustment structure group 22, when the number of adjustment structures 1211 in the adjustment structure group is greater than 1, the sizes of different adjustment structures in the adjustment structure group can also be the same.

[0105] For example, as shown in FIG. 1A, the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 is different, such as the first adjustment structure group 21 including three adjustment structures 1211 and the second adjustment structure group 22 including two adjustment structures 1211. Figure 15 The sizes of the adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 are the same, and the longest central axis L11 of the adjustment structure 1211 in the first adjustment structure group 21 is perpendicular to the longest central axis L12 of the adjustment structure 1211 in the second adjustment structure group 22.

[0106] For another example, as shown in FIG. 1B, on the basis of FIG. 1A, the sizes of the adjustment structures 1211 in the first adjustment structure group 21 are the same, the sizes of the adjustment structures 1211 in the second adjustment structure group 22 are the same, and the sizes of the adjustment structures 1211 in the first adjustment structure group 21 are different from the sizes of the adjustment structures 1211 in the second adjustment structure group 22. Figure 16 Figure 15 For another example, as shown in FIG. 1C, on the basis of FIG. 1A, the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 is the same, such as both of the adjustment structure groups including three adjustment structures 1211.

[0107] For another example, as shown in FIG. 1D, on the basis of FIG. 1A, the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 is different, such as the first adjustment structure group 21 including three adjustment structures 1211 and the second adjustment structure group 22 including two adjustment structures 1211. Figure 17 Figure 15 For another example, as shown in FIG. 1E, on the basis of FIG. 1A, the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 is the same, such as both of the adjustment structure groups including three adjustment structures 1211.

[0108] For another example, as shown in FIG. 1F, on the basis of FIG. 1A, the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 is different, such as the first adjustment structure group 21 including three adjustment structures 1211 and the second adjustment structure group 22 including two adjustment structures 1211. Figure 18 Figure 16 ​​​Based on this, the number of adjustment structures 1211 in the first adjustment structure group 21 and the second adjustment structure group 22 is the same. For example, both adjustment structure groups can include three adjustment structures 1211.

[0109] Furthermore, the material of the adjustment structure 1211 can include gold, silver, aluminum, silicon, gallium nitride, titanium oxide, etc. The adjustment structure 1211 can include one material or multiple materials. Moreover, the refractive index of the outer layer material of the adjustment structure 1211 in the first adjustment structure group 21 can be the same as or different from the refractive index of the outer layer material of the adjustment structure in the second adjustment structure group. For example, in... Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 Based on this, the refractive index of the outer layer of the adjustment structure 1211 in the first adjustment structure group 21 can be different from that of the outer layer of the adjustment structure in the second adjustment structure group.

[0110] Furthermore, for one of the adjustment structure groups 21 and 22, the number of adjustment structures 1211 in the adjustment structure group can be 1 or more. Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 Taking a quantity greater than 1 as an example. For instance, when the quantity is 1, multiple adjustment structures can be used as follows: Figure 19 As shown.

[0111] Optionally, when the aforementioned plurality of adjustment structures 1211 include some adjustment structures 1211 arranged along a direction perpendicular to the first direction Q (such as the aforementioned major axis direction L2), the different adjustment structures 1211 among these adjustment structures 1211 have the same phase delay for the first beam before passing through the adjustment layer 12. For example, it can be... Figure 14 The different adjustment structures 1211 arranged along direction L2 can have the same size, and / or, the different adjustment structures arranged along a direction perpendicular to the first direction have mutually parallel longest central axes, so that these adjustment structures 1211 have the same phase delay for the first beam before passing through adjustment layer 12. It is understood that the different adjustment structures 1211 arranged along direction L2 may also have different phase delays for the first beam. The plurality of adjustment structures 1211 may also not include the different adjustment structures 1211 arranged along a direction perpendicular to the first direction Q; for example, the plurality of adjustment structures 1211 may only include... Figure 14 The adjustment structure 1211 in the middle is not limited in this application embodiment.

[0112] The aforementioned multiple adjustment structures 1211 can be arranged in an array (e.g.) Figure 14The adjustment structures 1211 can be arranged in an array (as shown in the figure), or can not be arranged in an array.

[0113] Optionally, the difference between the phase retardation amounts of the first light beams before passing through the adjustment layer 12 in the extension direction of the longest central axis of the adjustment structure 1211 and in the direction perpendicular to the extension direction (two orthogonal directions) is in the range of [0.9π, 1.1π]. Figure 9 The angle between the long axis direction L2 of the liquid crystal in the liquid crystal layer 11 when no electric field is applied and the longest central axis (such as L11 and L12) of the adjustment structure 1211 is in the range of [40 degrees, 50 degrees], and the difference between the phase retardation amounts of the first light beams before passing through the adjustment layer 12 in the extension direction of the longest central axis of the adjustment structure 1211 and in the direction perpendicular to the extension direction (two orthogonal directions) is in the range of [0.9π, 1.1π]. At this time, the adjustment structure 1211 can realize the above-mentioned polarization direction adjustment of the first light beams. For example, the difference between the phase retardation amounts can be π, and / or the angle can be 45 degrees. It should be noted that the longest central axis of the adjustment structure 1211 can be rotated 45 degrees clockwise relative to the long axis direction L2, or 45 degrees counterclockwise, which is not limited in the embodiments of the present application.

[0114] In the embodiments of the present application, the parameters such as the material, size, shape, arrangement mode (related to the longest central axis of the adjustment structure 1211, arrangement order, distance between the centers of adjacent adjustment structures 1211, etc.) of the adjustment structure 1211 can be designed to make the adjustment layer 12 have the functions of the second phase adjustment and the polarization direction adjustment.

[0115] For example, in the example shown in the figure, the maximum length (such as the length of the longest central axis) of the adjustment structure 1211 can be in the range of [500 nanometers, 1000 nanometers], the maximum width (the width of the adjustment structure can be perpendicular to the longest central axis) of the adjustment structure 1211 can be in the range of [100 nanometers, 300 nanometers], and the distance between the centers of adjacent adjustment structures 1211 can be in the range of [600 nanometers, 1000 nanometers]. Figure 14

[0116] Further, regardless of the arrangement of the adjustment structure 1211, the maximum length of the adjustment structure 1211 can be smaller than the wavelength of the incident light, which can be referred to as a subwavelength structure. Generally, the wavelength of light is a nanometer-level length, so when the maximum length of the adjustment structure 1211 is smaller than the wavelength of light, the size of the adjustment structure 1211 is smaller, the thickness of the adjustment layer 12 where the adjustment structure 1211 is located is smaller, the thickness of the entire polarization-independent device is smaller, the driving voltage for driving the liquid crystal layer is smaller, and the power consumption for deflecting the liquid crystal layer is smaller.

[0117] In the embodiments of the present application, the maximum length of the adjustment structure 1211 is taken as an example of a nanometer-level length, which can be optionally a micrometer-level length, etc., which is not limited in the embodiments of the present application. When the adjustment structure 1211 has a micrometer-level size or a nanometer-level size, the adjustment structure 1211 can be referred to as a micro-nano structure.​

[0118] In the above embodiments, the portion of the adjustment layer 12 for performing the second phase adjustment and the polarization direction adjustment includes a plurality of adjustment structures 1211, which can belong to one layer of adjustment structures 1211, and each of the plurality of adjustment structures 1211 can include the first adjustment structure group and the second adjustment structure group, and the plurality of adjustment structures 1211 can include at least two adjustment structures arranged in the first direction in sequence, and optionally, the plurality of adjustment structures 1211 can further include at least two adjustment structures arranged in a direction perpendicular to the first direction in sequence.

[0119] Optionally, the portion of the adjustment layer 12 for performing the second phase adjustment and the polarization direction adjustment can include a plurality of sub-layers, and each of the plurality of sub-layers includes the plurality of adjustment structures 1211. The plurality of adjustment structures 1211 in each of the plurality of sub-layers can refer to the plurality of adjustment structures 1211 in the above embodiments, which will not be described herein.

[0120] It should be noted that, in the above embodiments, the adjustment layer utilizes the plurality of adjustment structures to perform the second phase adjustment and the polarization direction adjustment, and it can be understood that, when the adjustment layer needs to perform other adjustments (such as the third phase adjustment that the second light beam can pass through) in addition to the second phase adjustment and the polarization direction adjustment, the other adjustments can also be implemented by using the plurality of adjustment structures. At least one of the parameters such as the material, size, shape, and arrangement of the adjustment structure can be designed according to the function that the plurality of adjustment structures need to have.

[0121] Further, the liquid crystal layer can be deflected under the action of an electric field to adjust the phase of the light component having the first polarization direction P, and the electric field can be applied to the liquid crystal layer by an electric field applying assembly. The electric field applying assembly can be located inside or outside the polarization independent device, or a part of the electric field applying assembly is located inside the polarization independent device and the other part is located outside the polarization independent device.

[0122] For example, as shown in FIG. 6, the polarization independent device can further include an electric field applying assembly 61. The electric field applying assembly 61 can be located inside the polarization independent device, or a part of the electric field applying assembly 61 is located inside the polarization independent device and the other part is located outside the polarization independent device. Figure 20As shown, when the adjusting layer 12 includes the functional layer 121 and the reflective layer 122, on the basis of 12B, the polarization-independent device can further include: a transparent electrode layer 13 located on the side of the liquid crystal layer 11 away from the reflective layer 122, and a liquid crystal driving circuit 14 located on the side of the reflective layer 122 away from the liquid crystal layer 11; the reflective layer 122 is conductive; and the liquid crystal driving circuit 14 is configured to apply a voltage to the transparent electrode layer 13 and the reflective layer 122 to form an electric field between the transparent electrode layer 13 and the reflective layer 122. The above-mentioned electric field applying assembly includes the transparent electrode layer 13, the reflective layer 122, and the liquid crystal driving circuit 14. The above-mentioned transparent electrode layer 13 can be a transparent conductive material such as indium tin oxide, etc. The reflective layer 122 can include a plurality of reflective blocks (not shown in the figure) arranged in an array and spaced apart from each other, and an electric field exists between each reflective block and the transparent electrode layer 13. Figure 20

[0123] Further, the polarization-independent device can further include other structures, for example, as shown in Figure 21 , the polarization-independent device further includes: a first alignment layer 15, a second alignment layer 16, a planarization layer 17, and a passivation layer 18. In the polarization-independent device, the transparent electrode layer 13, the first alignment layer 15, the liquid crystal layer 11, the second alignment layer 16, the planarization layer 17 (also referred to as a cladding layer), the functional layer 121, the passivation layer 18, the reflective layer 122, and the liquid crystal driving circuit 14 are sequentially stacked. The first alignment layer 15 and the second alignment layer 16 are configured to align the liquid crystal layer 11, so that the long axis directions of the liquid crystals in the liquid crystal layer 11 are parallel (or tend to be parallel) to each other when no electric field is applied. The planarization layer 17 functions to planarize the surface of the functional layer 121, thereby supporting the subsequent packaging process of the liquid crystal layer 11.

[0124] The polarization-independent device can further include a substrate 19, and the liquid crystal driving circuit 14 can be located on the substrate 19. The transparent electrode layer 13, the first alignment layer 15, the liquid crystal layer 11, the second alignment layer 16, the planarization layer 17, the functional layer 121, the passivation layer 18, the reflective layer 122, and the liquid crystal driving circuit 14 can be sequentially arranged along the direction close to the substrate 19.

[0125] ​In summary, in the polarization-independent device provided by the embodiments of the present application, the adjusting layer can transmit, to the liquid crystal layer, the first light beam that has undergone the second phase adjustment and the polarization direction adjustment and the second light beam that has not undergone the second phase adjustment and the polarization direction adjustment based on the light component of the first polarization direction that has entered through the liquid crystal layer; and the propagation directions of the first light beam and the second light beam after passing through the liquid crystal layer are different. It can be seen that the light that has undergone the polarization direction adjustment and the light that has not undergone the polarization direction adjustment are subjected to different adjustments in the polarization-independent device, so that the light that has undergone the polarization direction adjustment and the light that has not undergone the polarization direction adjustment have different propagation directions when being emitted from the polarization-independent device, the two kinds of light are isolated in space, and the influence of the light component of the first polarization direction that has not undergone the polarization direction adjustment on the light adjustment device can be avoided.

[0126] Based on the polarization-independent device provided by the embodiments of the present application, the embodiments of the present application provide a light adjustment device comprising the polarization-independent device. The light adjustment device is used for adjusting the phase of light by using the polarization-independent device. For example, the light adjustment device can be any device capable of adjusting the phase of light, such as a WSS, a ROADM, a spatial light modulator, a display device, or the like.

[0127] Optionally, the light adjustment device further comprises a plurality of ports (including an input port and a plurality of output ports). The input port is configured to provide light to the side of the liquid crystal layer in the polarization-independent device; and the polarization-independent device is configured to emit the first light beam after passing through the liquid crystal layer (the first light beam after passing through the liquid crystal layer emitted from the side of the liquid crystal layer away from the adjusting layer) to the output port, and emit the second light beam after passing through the liquid crystal layer (the second light beam after passing through the liquid crystal layer emitted from the side of the liquid crystal layer away from the adjusting layer) to a direction deviating from the output port. In other words, when the light adjustment device comprises the input port and the plurality of output ports, the positions of the output ports can be designed so that the light beams emitted from the polarization-independent device to the output ports have undergone the first phase adjustment, the second phase adjustment and the polarization direction adjustment in the polarization-independent device, while the light beams that have not undergone the second phase adjustment and the polarization direction adjustment in the polarization-independent device will not be emitted to the output ports, so that the amount of light beams that have not undergone the polarization direction adjustment emitted to the output ports can be avoided to cause port crosstalk.

[0128] Further, according to the above embodiments, it can be known that the propagation paths of the light component of the first polarization direction before and after passing through the liquid crystal layer are located in the first plane, and the propagation paths of the first light beam and the second light beam emitted from the adjusting layer to the liquid crystal layer are located in the second plane; the first plane and the second plane are coplanar, or the included angle between the first plane and the second plane is greater than zero.

[0129] In the first implementation, when the first plane and the second plane are coplanar, the input port and the plurality of output ports are arranged in sequence along a direction parallel to the first plane and the polarization-independent device, and the polarization-independent device is perpendicular to the first plane. It should be noted that the polarization-independent device is a device obtained by stacking a plurality of films, and the polarization-independent device being perpendicular to the first plane means that the plurality of films are all perpendicular to the first plane, and the stacking direction of the plurality of films is parallel to the first plane.

[0130] As shown in Figure 11 , the first plane and the second plane are both paper planes, and the plurality of output ports are located on one side of the input port. The light beams that have undergone the first phase adjustment, the second phase adjustment, and the polarization direction adjustment in the polarization-independent device are directed to the output ports on the side of the input port, and the light beams that have not undergone the second phase adjustment and the polarization direction adjustment in the polarization-independent device are directed to the input port (as shown in Figure 11 ) or the side of the input port away from the output ports.

[0131] In the second implementation, when the included angle between the first plane and the second plane is greater than zero (for example, the included angle is 90 degrees), the plurality of ports are arranged in sequence along a direction parallel to the first plane and a reference plane, the reference plane is perpendicular to the first plane, and the polarization-independent device is rotated by -θ / 2 with respect to the reference plane; θ = α - β, α represents an adjustment angle of the polarization-independent device to the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjustment layer, and β represents an adjustment angle of the part of the polarization-independent device other than the adjustment layer to the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjustment layer. The first light beam before sequentially passing through the liquid crystal layer and the adjustment layer is also called the initial light beam, and the first light beam is obtained from the initial light beam by sequentially passing through the liquid crystal layer and the adjustment layer.

[0132] As shown in Figure 22 , the first plane N is perpendicular to the paper plane, the second plane is the paper plane, the reference plane M is perpendicular to the first plane N, and the dispersion direction of the ports is the up-down direction in Figure 22 . The arrangement direction of the plurality of ports (only one output port is shown in Figure 22 ) is the direction perpendicular to the paper plane in Figure 22 , and the arrangement direction is parallel to the first plane N and the reference plane M. At this time, the plurality of output ports can be located on one side or both sides of the input port. Moreover, the polarization-independent device is rotated by -θ / 2 with respect to the reference plane M. For example, assuming that θ = -30° (indicating a counterclockwise rotation of 30°), then -θ / 2 = 15° (indicating a clockwise rotation of 15°), and the polarization-independent device is rotated by 15 degrees clockwise with respect to the reference plane M.

[0133] In the second implementation, the adjustment of the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjusting layer by the polarization-independent device is related to three factors, including: (1) the first phase adjustment of the liquid crystal layer to the light component of the first polarization direction under the action of the electric field; (2) the second phase adjustment of the adjusting layer; and (3) the rotation angle of the polarization-independent device relative to the reference plane M. The adjustment of the propagation direction of the second light beam before sequentially passing through the liquid crystal layer and the adjusting layer by the polarization-independent device is related to factors (1) and (3).

[0134] When the liquid crystal layer is not applied with the electric field, the adjustment of the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjusting layer by the polarization-independent device is related to factors (2) and (3). Factor (2) causes the propagation direction to change by an angle θ, and factor (3) causes the propagation direction to change by an angle -θ, so that factors (2) and (3) offset each other in the change of the propagation direction.

[0135] When the liquid crystal layer is applied with the electric field, on the one hand, for the first light beam before sequentially passing through the liquid crystal layer and the adjusting layer, since factors (2) and (3) offset each other, the propagation direction of the light beam when exiting the polarization-independent device is related to factor (1), and the light beam can be transmitted to the out port under the action of the liquid crystal layer. It can be seen that the first light beam after the polarization direction adjustment can be directed to the out port after exiting the polarization-independent device. On the other hand, for the second light beam before sequentially passing through the liquid crystal layer and the adjusting layer, the propagation direction of the light beam when exiting the polarization-independent device is related to factors (1) and (3), and the light beam can be transmitted to either side of the plurality of ports in the dispersion direction under the influence of factors (1) and (3), thereby avoiding the second light beam without polarization direction adjustment from being directed to the out port after exiting the polarization-independent device.

[0136] Further, the light adjustment device can further include other structures, for example, as shown in Figure 11 or Figure 22 The light adjustment device further includes a lens (such as a convex lens) between the polarization-independent device and the plurality of ports.

[0137] The light adjustment device provided by the embodiments of the present application can be used in an optical network system. Based on this, the embodiments of the present application further provide an optical network system including the light adjustment device. For example, the optical network system uses light for communication, and the light adjustment device can adjust the phase of the light by using the polarization-independent device therein to achieve port exchange of the light.

[0138] The above merely describes optional embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A polarization independent device, characterized by, The polarization-independent device comprises a superimposed liquid crystal layer and an adjusting layer; The liquid crystal layer is configured to perform first phase adjustment on a light component of a first polarization direction passing through under the action of an electric field; The adjusting layer is configured to obtain a first light beam and a second light beam based on the light component of the first polarization direction passing through the liquid crystal layer, and transmit the first light beam and the second light beam to the liquid crystal layer; The first light beam is subjected to second phase adjustment and polarization direction adjustment in the adjusting layer; the second light beam is not subjected to the second phase adjustment and the polarization direction adjustment in the adjusting layer; the polarization direction of the first light beam is perpendicular to the polarization direction of the first light beam before the polarization direction adjustment; the first light beam and the second light beam have different propagation directions after passing through the liquid crystal layer.

2. The polarization independent device of claim 1, wherein, The portion of the adjusting layer for performing the second phase adjustment and the polarization direction adjustment comprises a plurality of adjusting structures arranged at intervals, and the plurality of adjusting structures comprise a first adjusting structure group and a second adjusting structure group arranged alternately along a first direction; An included angle between a longest central axis of an adjusting structure in the first adjusting structure group and a longest central axis of an adjusting structure in the second adjusting structure group ranges from 80 degrees to 100 degrees.

3. The polarization independent device of claim 2, wherein, The longest central axis of the adjusting structure in the first adjusting structure group is perpendicular to the longest central axis of the adjusting structure in the second adjusting structure group.

4. The polarization independent device according to claim 2 or 3, characterized in that, The adjusting structure is rod-shaped or ellipsoidal.

5. The polarization independent device according to any of claims 2 to 4, characterized in that The first adjusting structure group and the second adjusting structure group comprise at least two adjusting structures arranged sequentially along the first direction, and the at least two adjusting structures have an increasing or decreasing phase delay amount for the first light beam before passing through the adjusting layer.

6. The polarization independent device of claim 5, wherein, The at least two adjusting structures have a linearly increasing or linearly decreasing phase delay amount for the first light beam before passing through the adjusting layer.

7. The polarization independent device according to any of claims 2 to 6, characterized in that The polarization-independent device satisfies at least one of the following conditions: The number of adjusting structures in the first adjusting structure group is the same as that in the second adjusting structure group; Adjusting structures of the same order in the first adjusting structure group and the second adjusting structure group have the same size; For one of the first adjusting structure group and the second adjusting structure group, when the number of adjusting structures in the adjusting structure group is greater than 1, the sizes of different adjusting structures in the adjusting structure group are different.

8. The polarization independent device according to any of claims 2 to 7, characterized in that Different adjusting structures arranged along a direction perpendicular to the first direction have the same phase delay amount for the first light beam before passing through the adjusting layer.

9. The polarization independent device of claim 8, wherein, Longest central axes of different adjusting structures arranged along a direction perpendicular to the first direction are parallel, and / or sizes of different adjusting structures arranged along a direction perpendicular to the first direction are the same.

10. The polarization independent device according to any of claims 2 to 9, characterized in that For one of the adjusting structures, a difference between a phase delay amount of the adjusting structure for the first light beam in an extension direction of a longest central axis of the adjusting structure and a phase delay amount of the adjusting structure for the first light beam in a direction perpendicular to the extension direction ranges from 0.9π to 1.1π; and an included angle between the longest central axis of the adjusting structure and a long axis of liquid crystal in the liquid crystal layer when no electric field is applied ranges from 40 degrees to 50 degrees.

11. The polarization independent device of claim 10, wherein, The difference between the phase retardations is π, and / or, the angle between the longest central axis of the adjustment structure and the long axis of the liquid crystal in the liquid crystal layer when no electric field is applied is 45 degrees.

12. The polarization independent device according to any of claims 2 to 11, characterized in that The maximum length of the adjustment structure is less than the wavelength of the light.

13. The polarization independent device of claim 12, wherein, The maximum length of the adjustment structure is a nanometer level length.

14. The polarization independent device according to any of claims 2 to 13, characterized in that The part of the adjustment layer for performing the second phase adjustment and the polarization direction adjustment includes a plurality of sub-layers, and the sub-layers include the plurality of adjustment structures.

15. The polarization independent device according to any of claims 2 to 14, characterized in that The part of the adjustment layer for performing the second phase adjustment and the polarization direction adjustment includes a plurality of adjustment structures arranged at intervals, and the second phase adjustment and the polarization direction adjustment are both related to at least one parameter of the material, size, shape and arrangement of the adjustment structure.

16. The polarization independent device of claim 15, wherein, The plurality of adjustment structures form a metasurface structure.

17. The polarization independent device according to any of claims 1 to 16, characterized in that The propagation paths of the light components of the first polarization direction before and after passing through the liquid crystal layer are both located in a first plane, and the propagation paths of the first light beam and the second light beam from the adjustment layer to the liquid crystal layer are both located in a second plane. The first plane and the second plane are coplanar, or the angle between the first plane and the second plane is greater than zero degrees.

18. The polarization independent device of claim 17, wherein, The angle between the first plane and the second plane is 90 degrees.

19. The polarization independent device according to any of claims 1 to 18, characterized in that The second light beam passes through a third phase adjustment different from the second phase adjustment in the adjustment layer.

20. The polarization independent device according to any of claims 1 to 19, characterized in that The first polarization direction is parallel to the long axis of the liquid crystal in the liquid crystal layer when no electric field is applied.

21. The polarization independent device according to any of claims 1 to 20, characterized in that The adjustment layer includes a functional layer and a reflective layer stacked in sequence in the direction away from the liquid crystal layer, and the reflective surface of the reflective layer faces the functional layer; the second phase adjustment and the polarization direction adjustment occur in the functional layer.

22. The polarization independent device of claim 21, wherein, The polarization independent device further includes a transparent electrode layer and a liquid crystal driving circuit, the transparent electrode layer is located on the side of the liquid crystal layer away from the reflective layer, and the liquid crystal driving circuit is located on the side of the reflective layer away from the liquid crystal layer; the reflective layer is conductive. The liquid crystal driving circuit is configured to apply a voltage to the transparent electrode layer and the reflective layer to form the electric field between the transparent electrode layer and the reflective layer.

23. The polarization independent device of claim 22, wherein, The polarization independent device includes the transparent electrode layer, a first alignment layer, the liquid crystal layer, a second alignment layer, a flat layer, the functional layer, a passivation layer, the reflective layer and the liquid crystal driving circuit stacked in sequence.

24. An optical adjustment device, characterized by The light adjustment apparatus includes the polarization independent device of any one of claims 1 to 23, and the light adjustment apparatus is configured to adjust the phase of the light by using the polarization independent device.

25. The light conditioning device of claim 24, wherein, The light adjustment apparatus further includes a plurality of ports. The plurality of ports includes an input port and a plurality of output ports, the input port is configured to provide light to the side of the liquid crystal layer in the polarization independent device, the polarization independent device is configured to direct the first light beam after passing through the liquid crystal layer to the output port, and direct the second light beam after passing through the liquid crystal layer to a direction deviating from the output port.

26. The light conditioning device of claim 25, wherein, The first polarization direction light component is in a first plane before and after passing through the liquid crystal layer, and the first light beam and the second light beam are in a second plane when propagating from the adjusting layer to the liquid crystal layer; the first plane and the second plane are coplanar. The input port and the plurality of output ports are arranged in sequence along a direction parallel to the first plane and the polarization independent device, and the polarization independent device is perpendicular to the first plane.

27. The light conditioning device of claim 25, wherein, The first polarization direction light component is in a first plane before and after passing through the liquid crystal layer, and the first light beam and the second light beam are in a second plane when propagating from the adjusting layer to the liquid crystal layer; the first plane and the second plane are coplanar. The plurality of ports are arranged in sequence along a direction parallel to the first plane and a reference plane, and the reference plane is perpendicular to the first plane; the polarization independent device is rotated by -θ / 2 relative to the reference plane; θ=α-β, α represents an adjusting angle of the polarization independent device to the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjusting layer; and β represents an adjusting angle of a part of the polarization independent device other than the adjusting layer to the propagation direction of the first light beam before sequentially passing through the liquid crystal layer and the adjusting layer.

28. The light conditioning device of any one of claims 25 to 27, wherein, The optical adjustment device further comprises a lens between the polarization independent device and the plurality of ports.

29. An optical network system, characterized by The optical network system comprises the optical adjustment device according to any one of claims 24 to 28.

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