A polarization-insensitive liquid crystal on silicon device

Abstract

The utility model relates to optical super-structured surface technical field especially, and it is a kind of polarization-insensitive silicon-based liquid crystal device.The silicon-based liquid crystal device: first transparent electrode receives incident light and output polarization conversion and phase modulation light beam, and incident light includes polarization state orthogonal first polarization direction linearly polarized light and second polarization direction linearly polarized light;First layer liquid crystal cooperates first transparent electrode and carries out phase modulation to first polarization direction linearly polarized light;Second layer liquid crystal cooperates second transparent electrode and carries out phase modulation to first polarization direction linearly polarized light;Super-structured surface quarter-wave plate cooperates silica dielectric layer, metal reflection layer and converts first polarization direction linearly polarized light into second polarization direction linearly polarized light, and second polarization direction linearly polarized light is converted into first polarization direction linearly polarized light, to realize a kind of polarization-insensitive silicon-based liquid crystal technical scheme that can realize polarization conversion and can carry out phase modulation.

Description

Technical Field

[0001] This invention relates to the field of optical metasurface technology, and in particular to a polarization-insensitive silicon-based liquid crystal device. Background Technology

[0002] LCOS (Liquid Crystal on Silicon) is a small reflective display device based on liquid crystal technology, also known as a spatial light modulator. This device works by controlling the phase or intensity of light through a liquid crystal layer, thus offering features such as flexible light field manipulation, reprogrammability, and high resolution. Due to its high efficiency and compact design, LCOS technology is widely used in projection displays, optical sensing, optical communication, and many other fields.

[0003] Traditional LCOS devices use nematic liquid crystals as modulation materials. These liquid crystal molecules have a typical uniaxial crystal structure and can undergo orientation changes when an electric field is applied. For example, assuming no external voltage is applied, all liquid crystal molecules in the liquid crystal layer are distributed in the XY plane, with the Z-axis perpendicular to the XY plane, and the long axes of the liquid crystal molecules roughly aligned along the X-axis. When a voltage is applied to the liquid crystal molecules, they rotate, gradually adjusting from the X-axis direction to the Z-axis direction. This rotation angle is directly related to the magnitude of the applied voltage. This phenomenon causes a change in the refractive index of the liquid crystal layer, thereby achieving phase modulation of polarized light. For incident light polarized along the X-axis (commonly called extraordinary light or e-ray), the refractive index changes with the orientation of the liquid crystal molecules, so phase control can be achieved by adjusting the voltage. However, for incident light polarized along the Y-axis (i.e., ordinary light or o-ray), since the refractive index does not change with the orientation of the liquid crystal molecules, phase modulation is not possible. When the incident light contains polarization components in both the X and Y directions, additional optical elements are often required to perform polarization decomposition and conversion processing on the optical signal. These additional optical components not only increase the complexity of the device but also take up more space, leading to an increase in the overall system cost and size.

[0004] Therefore, a phase modulation scheme for silicon-based liquid crystals that is polarization-independent on the incident light is needed. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a polarization-insensitive silicon-based liquid crystal device.

[0006] The present invention provides a polarization-insensitive silicon-based liquid crystal device, comprising a first transparent electrode, a first liquid crystal layer, a second transparent electrode, a second liquid crystal layer, a metasurface quarter-wave plate, a silicon dioxide dielectric layer, a metal reflective layer, and a silicon substrate.

[0007] The first transparent electrode is disposed on the first surface of the first liquid crystal layer;

[0008] The second transparent electrode is disposed between the second surface of the first liquid crystal layer and the first surface of the second liquid crystal layer;

[0009] The second surface of the second layer of liquid crystal is disposed on the first surface of the metasurface quarter-wave plate;

[0010] The second surface of the metasurface quarter-wave plate is disposed on the first surface of the silicon dioxide dielectric layer;

[0011] The second surface of the silicon dioxide dielectric layer is disposed on the first surface of the metal reflective layer;

[0012] The second surface of the metal reflective layer is disposed on the silicon substrate;

[0013] The first transparent electrode is used to receive incident light and output polarization-converted and phase-modulated beams. The incident light includes linearly polarized light with orthogonal polarization states in a first polarization direction and linearly polarized light with orthogonal polarization states in a second polarization direction.

[0014] The first layer of liquid crystal is used in conjunction with the first transparent electrode to perform phase modulation on linearly polarized light in the first polarization direction;

[0015] The second layer of liquid crystal is used in conjunction with the second transparent electrode to perform phase modulation on linearly polarized light in the first polarization direction;

[0016] The metasurface quarter-wave plate is used in conjunction with the silicon dioxide dielectric layer and the metal reflective layer to convert linearly polarized light in the first polarization direction into linearly polarized light in the second polarization direction, and to convert linearly polarized light in the second polarization direction into linearly polarized light in the first polarization direction.

[0017] In one possible implementation, the metasurface quarter-wave plate is composed of a periodically arranged array of cross-shaped silicon nanopillars.

[0018] In one possible implementation, the thickness of the metal reflective layer is 100~300nm.

[0019] In one possible implementation, the thickness of the silicon dioxide dielectric layer is 300~500 nm.

[0020] In one possible implementation, the period of the cross-shaped silicon nanopillar array is 700 nm.

[0021] In one possible implementation, each nanopillar in the cross-shaped silicon nanopillar array has a height of 800-1000 nm, a cross-shaped cross-section, a length of 200-400 nm, and a width of 200-400 nm.

[0022] In one possible implementation, the long axis of the cross-section of the nanopillar forms an angle of 45° ± 5° with the first polarization direction.

[0023] In one possible implementation, the orientation planes of the first liquid crystal layer and the second liquid crystal layer are at an angle of 0°.

[0024] This invention also provides another polarization-insensitive silicon-based liquid crystal device, including a first transparent electrode, a first liquid crystal layer, a second transparent electrode, a second liquid crystal layer, a metasurface quarter-wave plate, a silicon dioxide dielectric layer, a metal reflective layer, and a silicon substrate.

[0025] The first transparent electrode is disposed on the first surface of the first liquid crystal layer;

[0026] The second transparent electrode is disposed between the second surface of the first liquid crystal layer and the first surface of the second liquid crystal layer;

[0027] The second surface of the second layer of liquid crystal is disposed on the first surface of the metasurface quarter-wave plate;

[0028] The second surface of the metasurface quarter-wave plate is disposed on the first surface of the silicon dioxide dielectric layer;

[0029] The second surface of the silicon dioxide dielectric layer is disposed on the first surface of the metal reflective layer;

[0030] The second surface of the metal reflective layer is disposed on the silicon substrate;

[0031] The first transparent electrode is used to receive incident light and output polarization-converted and phase-modulated beams. The incident light includes linearly polarized light with orthogonal polarization states in a first polarization direction and linearly polarized light with orthogonal polarization states in a second polarization direction.

[0032] The first layer of liquid crystal is used in conjunction with the first transparent electrode to perform phase modulation on linearly polarized light in the first polarization direction;

[0033] The second layer of liquid crystal is used in conjunction with the second transparent electrode to perform phase modulation on linearly polarized light in the second polarization direction;

[0034] The metasurface quarter-wave plate is used in conjunction with the silicon dioxide dielectric layer and the metal reflective layer to convert linearly polarized light in the first polarization direction into linearly polarized light in the second polarization direction, and to convert linearly polarized light in the second polarization direction into linearly polarized light in the first polarization direction.

[0035] In one possible implementation, the orientation planes of the first liquid crystal layer and the second liquid crystal layer are at an angle of 90°.

[0036] The technical solution provided by this utility model has at least the following beneficial effects:

[0037] Through the synergistic effect of devices such as the first layer of liquid crystal, the second layer of liquid crystal, and the metasurface quarter-wave plate, the combination of metasurface and liquid crystal modulation technology in silicon-based liquid crystal is realized, which can achieve both polarization conversion and phase modulation, making the application prospects of silicon-based liquid crystal in various optical systems more extensive. Attached Figure Description

[0038] Figure 1 A schematic diagram of the structure of a polarization-insensitive silicon-based liquid crystal device provided for an embodiment of this utility model;

[0039] Figure 2 A perspective view of the square lattice of the reflective polarization conversion device provided in the embodiment of this utility model;

[0040] Figure 3 A top view of a reflective polarization converter device provided in an embodiment of this utility model;

[0041] Figure 4 A side view of a reflective polarization converter device provided in an embodiment of this utility model;

[0042] Figure 5 A schematic diagram of another polarization-insensitive silicon-based liquid crystal device provided for an embodiment of this utility model;

[0043] In the attached diagram:

[0044] 10. Silicon-based liquid crystal device; 11. First transparent electrode; 12. First liquid crystal layer; 13. Second transparent electrode; 14. Second liquid crystal layer; 15. Metasurface quarter-wave plate; 16. Silicon dioxide dielectric layer; 17. Metal reflective layer; 18. Silicon substrate. Detailed Implementation

[0045] To enhance understanding of this utility model, it will be described in further detail below with reference to the accompanying drawings and embodiments. These embodiments are only used to explain this utility model and do not limit the scope of protection of this utility model.

[0046] Please refer to Figures 1 to 5 The present invention provides a polarization-insensitive silicon-based liquid crystal device 10, comprising a first transparent electrode 11, a first liquid crystal layer 12, a second transparent electrode 13, a second liquid crystal layer 14, a metasurface quarter-wave plate 15, a silicon dioxide dielectric layer 16, a metal reflective layer 17, and a silicon substrate 18.

[0047] The first transparent electrode 11 is disposed on the first surface of the first liquid crystal layer 12;

[0048] The second transparent electrode 13 is disposed between the second surface of the first liquid crystal layer 12 and the first surface of the second liquid crystal layer 14;

[0049] The second surface of the second layer of liquid crystal 14 is disposed on the first surface of the metasurface quarter-wave plate 15;

[0050] The second surface of the metasurface quarter-wave plate 15 is disposed on the first surface of the silicon dioxide dielectric layer 16;

[0051] The second surface of the silicon dioxide dielectric layer 16 is disposed on the first surface of the metal reflective layer 17;

[0052] The second surface of the metal reflective layer 17 is disposed on the silicon substrate 18;

[0053] The first transparent electrode 11 is used to receive incident light and output polarization-converted and phase-modulated beams. The incident light includes linearly polarized light with orthogonal polarization states in a first polarization direction and linearly polarized light with orthogonal polarization states in a second polarization direction.

[0054] The first layer of liquid crystal 12 is used in conjunction with the first transparent electrode 11 to perform phase modulation on linearly polarized light in the first polarization direction;

[0055] The second layer of liquid crystal 14 is used in conjunction with the second transparent electrode 13 to perform phase modulation on linearly polarized light in the first polarization direction;

[0056] The metasurface quarter-wave plate 15 is used in conjunction with the silicon dioxide dielectric layer 16 and the metal reflective layer 17 to convert linearly polarized light in the first polarization direction into linearly polarized light in the second polarization direction, and to convert linearly polarized light in the second polarization direction into linearly polarized light in the first polarization direction.

[0057] In this embodiment, the first liquid crystal layer 12 and the second liquid crystal layer 14 can adopt a conventional liquid crystal cell structure containing nematic liquid crystals. The first liquid crystal layer 12 cooperates with the first transparent electrode 11, and the second liquid crystal layer 14 cooperates with the second transparent electrode 13, realizing precise control of the electric field strength of the liquid crystal molecules in the first liquid crystal layer 12 and the second liquid crystal layer 14, thereby achieving efficient phase modulation of linearly polarized light in the first polarization direction. For example, in the liquid crystal cell structure, the liquid crystal molecules can be disposed on the pixelation electrode, which can be driven by the driving circuit to form an electric field with the external electrode (such as the first transparent electrode 11 and the second transparent electrode 13), thereby driving the liquid crystal molecules to rotate. The orientation plane angle between the first liquid crystal layer 12 and the second liquid crystal layer 14 is 0°. Figure 1 and Figure 3The first polarization direction is the X-axis, and the second polarization direction is the Y-axis. The working plane of the silicon-based liquid crystal device 10 is defined as the XY plane, where the Z-axis is the normal to the XY plane. In the absence of an electric field, the long axis of the liquid crystal molecules is aligned with the X-axis. When a voltage is applied, the orientation of the liquid crystal molecules rotates from the X-axis to the Z-axis; the magnitude of the voltage determines the angle of rotation. The orientation of the liquid crystal molecules changes within the XZ plane, thus affecting the light propagation characteristics. If the polarization direction of the incident light is the X-axis, the incident light is an extraordinary ray (e-ray), and its refractive index changes with the orientation of the liquid crystal molecules, thus achieving phase modulation. If the polarization direction of the incident light is the Y-axis, the incident light is an ordinary ray (o-ray), and its refractive index does not change with the orientation of the liquid crystal molecules; therefore, phase modulation cannot be achieved by voltage adjustment.

[0058] In one specific implementation, the incident light is represented by optical signal A, and the polarization-converted and phase-modulated beam is represented by optical signal A'. Optical signal A includes linearly polarized light Ax with orthogonal polarization states in a first polarization direction (i.e., the X-axis direction) and linearly polarized light Ay with orthogonal polarization states in a second polarization direction (i.e., the Y-axis direction), denoted as A = Ax + Ay.

[0059] The process of optical signal A being converted into optical signal A' is as follows:

[0060] Optical signal A passes through the first transparent electrode 11 and enters the first liquid crystal layer 12. Linearly polarized light Ax undergoes phase adjustment under the action of the first liquid crystal layer 12, transforming into linearly polarized light Ax(θ-φ1), where θ is the applied phase and φ1 is the phase error. Optical signal A is then transformed into optical signal A1, denoted as A1 = Ax(θ-φ1) + Ay.

[0061] Optical signal A1 passes through the second transparent electrode 13 and enters the second liquid crystal layer 14. The second liquid crystal layer 14 provides a compensating phase φ2 to the linearly polarized light Ax(θ-φ1) that is equal to the phase error φ1. The linearly polarized light Ax(θ-φ1) is transformed into linearly polarized light Ax(θ-φ1+φ2)=Ax(θ). Optical signal A1 is transformed into optical signal A2, denoted as A2=Ax(θ)+Ay.

[0062] Optical signal A2 enters the metasurface quarter-wave plate 15. The metasurface quarter-wave plate 15, the silicon dioxide dielectric layer 16, and the metal reflective layer 17 work together to perform polarization conversion on optical signal A2 (i.e., only the polarization direction changes, the phase remains unchanged). Optical signal A2 is transformed into optical signal A2', denoted as A2'=A'y(θ)+A'x. That is, linearly polarized light Ax(θ) in the first polarization direction is converted into linearly polarized light A'y(θ) in the second polarization direction, and linearly polarized light Ay in the second polarization direction is converted into linearly polarized light A'x in the first polarization direction.

[0063] Optical signal A2' enters the second liquid crystal layer 14 through the metasurface quarter-wave plate 15. The second liquid crystal layer 14 provides a compensating phase φ2 for the linearly polarized light A'x, transforming the linearly polarized light A'x into linearly polarized light A'x(φ2). Optical signal A2' is then transformed into optical signal A1', denoted as A1' = A'y(θ) + A'x(φ2).

[0064] The optical signal A1' passes through the second transparent electrode 13 and enters the first liquid crystal layer 12. The linearly polarized light A'x(φ2) undergoes phase adjustment under the action of the first liquid crystal layer 12, transforming into linearly polarized light A'x(φ2+θ-φ1)=A'x(θ). The optical signal A1' is then transformed into the optical signal A', denoted as A'=A'y(θ)+A'x(θ). The optical signal A', as a polarization-converted and phase-modulated beam, is output from the first transparent electrode 11.

[0065] The LCOS device, or silicon-based liquid crystal device 10, integrates a metasurface quarter-wave plate 15, giving the device greater flexibility and precision in optical signal processing. The key function of the metasurface quarter-wave plate 15 is its ability to convert linearly polarized light into circularly polarized light. This polarization conversion capability allows the LCOS device to precisely control and allocate the polarization state of incident light, thereby achieving high-precision control of the optical signal. Furthermore, through fine manipulation of the liquid crystal molecules in the first liquid crystal layer 12 and the second liquid crystal layer 14, the LCOS device can achieve efficient phase changes during optical signal modulation, thereby optimizing the optical signal processing and conversion process.

[0066] In addition, the metal reflective layer 17 can reflect the transmitted circularly polarized light back to the metasurface quarter-wave plate 15, which can greatly improve the interaction between light and the device and significantly enhance the conversion efficiency of polarized light. The measured efficiency can exceed 90%, achieving maximum light utilization and minimum loss.

[0067] This application, by combining a metasurface quarter-wave plate 15 with a dual-layer liquid crystal (first liquid crystal layer 12 and second liquid crystal layer 14), enables the LCOS device to not only perform precise polarization diversity and conversion of optical signals, but also possesses advantages such as simple metasurface design and small size, thereby effectively reducing the complexity and manufacturing cost of the device. This simplified design not only improves the system integration, but also makes the promotion of this technology easier. Compared with traditional optical systems, the advantages of the LCOS device in this application in terms of size and cost make it more promising for applications requiring efficient optical modulation and spatial optimization, such as display technology, optical communication, and optical imaging.

[0068] In one possible implementation, the metasurface quarter-wave plate 15 is composed of a periodically arranged array of cross-shaped silicon nanopillars.

[0069] In one possible implementation, the thickness of the metal reflective layer 17 is 100~300nm.

[0070] In one possible implementation, the thickness of the silicon dioxide dielectric layer 16 is 300~500 nm.

[0071] In one possible implementation, the period of the cross-shaped silicon nanopillar array is 700 nm.

[0072] In one possible implementation, each nanopillar in the cross-shaped silicon nanopillar array has a height of 800-1000 nm, a cross-shaped cross-section, a length of 200-400 nm, and a width of 200-400 nm.

[0073] In one possible implementation, the long axis of the cross-section of the nanopillar forms an angle of 45° ± 5° with the first polarization direction.

[0074] In this embodiment, as Figures 2 to 4 The combined structure of the metasurface quarter-wave plate 15, the silica dielectric layer 16, and the metal reflective layer 17 can be considered as a reflective polarization conversion device. The preferred materials for the metal reflective layer 17 are aluminum, gold, silver, and copper, with a thickness h3 of 100–300 nm and a reflectivity >95%, serving as an optical reflective substrate. The silica dielectric layer 16 has a thickness h2 of 300–500 nm. The metasurface quarter-wave plate 15 is composed of a cross-shaped array of silicon nanopillars, with a fixed array period P of 700 nm, exhibiting subwavelength characteristics. Each nanopillar has a height h1 between 800 and 1000 nm, a cross-shaped cross-section, a length Ly = 200–400 nm, a width Lx = 200–400 nm, and a width W = 200 nm for the small rectangular blocks. One of the most critical design parameters is that the long axis of the nanopillar's cross-section must form a 45° angle with the incident X-polarization direction, with manufacturing tolerances allowed within ±5°.

[0075] It should be noted that in the metasurface waveplate, a reference coordinate system xoy is established with a horizontal line (X-axis) and a vertical line (Y-axis). Simultaneously, a local coordinate system uov is established based on the major axis (U-axis) and minor axis (V-axis) of the cross-shaped silicon nanopillars, with both coordinate systems sharing the origin o (i.e., the center of the nanopillars). The angle between the U-axis and the X-axis is denoted as θ. Linearly polarized light incident along the X-axis is resolved to the U-axis and V-axis directions due to the birefringence effect of the nanopillars. Because the light wave experiences different phase delays (δ) as it propagates along these two principal axes, the polarization direction of the reconstituted outgoing light rotates. This rotation angle is determined by the angle θ and the phase delay, i.e., the phase difference δ. The entire polarization conversion mechanism can be rigorously described using Jones matrix theory: any incident polarized light is first decomposed in the uv coordinate system, and then each part undergoes specific phase modulation.

[0076] It can be known that:

[0077]

[0078] If a phase difference δ is introduced, the light emitted from the metasurface can be expressed as:

[0079]

[0080] Projecting back onto the X and Y axes, we get:

[0081]

[0082] Therefore, the Jones matrix of this metasurface waveplate can be expressed as:

[0083]

[0084] Here, consider a metasurface with a phase difference of π / 2, i.e., a quarter-wave plate. If the angle between the major axis and the X-axis is 45°, then when linearly polarized light with polarization along the X-axis is incident:

[0085]

[0086] It can be observed that the polarization direction of the emitted light has changed from the X-axis to the Y-axis.

[0087] In one possible implementation, such as Figure 1 The angle between the orientation planes of the first liquid crystal layer 12 and the second liquid crystal layer 14 is 0°.

[0088] like Figure 5Another polarization-insensitive silicon-based liquid crystal device 10 provided by this utility model includes a first transparent electrode 11, a first liquid crystal layer 12, a second transparent electrode 13, a second liquid crystal layer 14, a metasurface quarter-wave plate 15, a silicon dioxide dielectric layer 16, a metal reflective layer 17, and a silicon substrate 18.

[0089] The first transparent electrode 11 is disposed on the first surface of the first liquid crystal layer 12;

[0090] The second transparent electrode 13 is disposed between the second surface of the first liquid crystal layer 12 and the first surface of the second liquid crystal layer 14;

[0091] The second surface of the second layer of liquid crystal 14 is disposed on the first surface of the metasurface quarter-wave plate 15;

[0092] The second surface of the metasurface quarter-wave plate 15 is disposed on the first surface of the silicon dioxide dielectric layer 16;

[0093] The second surface of the silicon dioxide dielectric layer 16 is disposed on the first surface of the metal reflective layer 17;

[0094] The second surface of the metal reflective layer 17 is disposed on the silicon substrate 18;

[0095] The first transparent electrode 11 is used to receive incident light and output polarization-converted and phase-modulated beams. The incident light includes linearly polarized light with orthogonal polarization states in a first polarization direction and linearly polarized light with orthogonal polarization states in a second polarization direction.

[0096] The first layer of liquid crystal 12 is used in conjunction with the first transparent electrode 11 to perform phase modulation on linearly polarized light in the first polarization direction;

[0097] The second liquid crystal layer 14 is used in conjunction with the second transparent electrode 13 to perform phase modulation on linearly polarized light in the second polarization direction;

[0098] The metasurface quarter-wave plate 15 is used in conjunction with the silicon dioxide dielectric layer 16 and the metal reflective layer 17 to convert linearly polarized light in the first polarization direction into linearly polarized light in the second polarization direction, and to convert linearly polarized light in the second polarization direction into linearly polarized light in the first polarization direction.

[0099] In one possible implementation, such as Figure 5 The orientation planes of the first liquid crystal layer 12 and the second liquid crystal layer 14 are angled at 90°.

[0100] In this embodiment, the first liquid crystal layer 12 and the second liquid crystal layer 14 can adopt a conventional liquid crystal cell structure containing nematic liquid crystals. The first liquid crystal layer 12, in conjunction with the first transparent electrode 11, achieves precise control of the electric field strength of the liquid crystal molecules in the first liquid crystal layer 12, thereby efficiently modulating the phase of linearly polarized light in the first polarization direction. The second liquid crystal layer 14, in conjunction with the second transparent electrode 13, achieves precise control of the electric field strength of the liquid crystal molecules in the second liquid crystal layer 14, thereby efficiently modulating the phase of linearly polarized light in the second polarization direction. The first polarization direction is the X-axis direction, and the second polarization direction is the Y-axis direction. The working plane of the silicon-based liquid crystal device 10 is defined as the XY plane, where the Z-axis direction is the normal to the XY plane. In the absence of an electric field, the long axis of the liquid crystal molecules in the first liquid crystal layer 12 is aligned with the X-axis direction, and the long axis of the liquid crystal molecules in the second liquid crystal layer 14 is aligned with the Y-axis direction. When a voltage is applied, the orientation of the liquid crystal molecules rotates. In the first liquid crystal layer 12, the liquid crystal molecules change from the X-axis to the Z-axis, and in the second liquid crystal layer 14, the liquid crystal molecules change from the Y-axis to the Z-axis. The magnitude of the voltage determines the angle of rotation. If the polarization direction of the incident light is along the X-axis, the incident light is an extraordinary ray (e-ray), and its refractive index changes with the orientation of the liquid crystal molecules in the first liquid crystal layer 12, thus achieving phase modulation. If the polarization direction of the incident light is along the Y-axis, the incident light is an ordinary ray (o-ray), and its refractive index changes with the orientation of the liquid crystal molecules in the second liquid crystal layer 14, thus achieving phase modulation.

[0101] In one specific implementation, the incident light is represented by optical signal B, and the polarization-converted and phase-modulated beam is represented by optical signal B'. Optical signal B includes linearly polarized light Bx with orthogonal polarization states in a first polarization direction (i.e., the X-axis direction) and linearly polarized light By with orthogonal polarization states in a second polarization direction (i.e., the Y-axis direction), denoted as B = Bx + By.

[0102] The process by which optical signal B is converted into optical signal B' is as follows:

[0103] The optical signal B passes through the first transparent electrode 11 and enters the first liquid crystal layer 12. The linearly polarized light Bx undergoes phase adjustment under the action of the first liquid crystal layer 12, transforming into linearly polarized light Bx(θ / 2), where θ / 2 is the applied phase. The optical signal B is then transformed into the optical signal B1, denoted as B1 = Bx(θ / 2) + By.

[0104] Optical signal B1 passes through the second transparent electrode 13 and enters the second liquid crystal layer 14. Linearly polarized light By undergoes phase adjustment under the action of the second liquid crystal layer 14, transforming into linearly polarized light By(θ / 2), where θ / 2 is the applied phase. Optical signal B1 is then transformed into optical signal B2, denoted as B2 = Bx(θ / 2) + By(θ / 2).

[0105] Optical signal B2 enters the metasurface quarter-wave plate 15. The metasurface quarter-wave plate 15, the silicon dioxide dielectric layer 16, and the metal reflective layer 17 work together to perform polarization conversion on optical signal B2, transforming optical signal B2 into optical signal B2', denoted as B2'=B'y(θ / 2)+B'x(θ / 2). That is, linearly polarized light Bx(θ / 2) in the first polarization direction is converted into linearly polarized light B'y(θ / 2) in the second polarization direction, and linearly polarized light By(θ / 2) in the second polarization direction is converted into linearly polarized light B'x(θ / 2) in the first polarization direction.

[0106] Optical signal B2' enters the second liquid crystal layer 14 through the metasurface quarter-wave plate 15. Linearly polarized light B'y(θ / 2) undergoes phase adjustment under the action of the second liquid crystal layer 14, transforming into linearly polarized light B'y(θ / 2+θ / 2)=B'y(θ), where θ / 2 is the applied phase. Optical signal B2' is then transformed into optical signal B1', denoted as B1'=B'y(θ)+B'x(θ / 2).

[0107] The optical signal B1' passes through the second transparent electrode 13 and enters the first liquid crystal layer 12. The linearly polarized light B'x(θ / 2) undergoes phase adjustment under the action of the first liquid crystal layer 12, transforming into linearly polarized light B'x(θ / 2+θ / 2)=B'x(θ). The optical signal B1' is then transformed into the optical signal B', denoted as B'=B'y(θ)+B'x(θ). The optical signal B', as a polarization-converted and phase-modulated beam, is output from the first transparent electrode 11.

[0108] The above embodiments should not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent conversion fall within the protection scope of the present invention.

Claims

1. A polarization-insensitive silicon-based liquid crystal device, characterized in that, It includes a first transparent electrode, a first liquid crystal layer, a second transparent electrode, a second liquid crystal layer, a metasurface quarter-wave plate, a silicon dioxide dielectric layer, a metal reflective layer, and a silicon substrate; The first transparent electrode is disposed on the first surface of the first liquid crystal layer; The second transparent electrode is disposed between the second surface of the first liquid crystal layer and the first surface of the second liquid crystal layer; The second surface of the second layer of liquid crystal is disposed on the first surface of the metasurface quarter-wave plate; The second surface of the metasurface quarter-wave plate is disposed on the first surface of the silicon dioxide dielectric layer; The second surface of the silicon dioxide dielectric layer is disposed on the first surface of the metal reflective layer; The second surface of the metal reflective layer is disposed on the silicon substrate; The first transparent electrode is used to receive incident light and output polarization-converted and phase-modulated beams. The incident light includes linearly polarized light with orthogonal polarization states in a first polarization direction and linearly polarized light with orthogonal polarization states in a second polarization direction. The first layer of liquid crystal is used in conjunction with the first transparent electrode to perform phase modulation on linearly polarized light in the first polarization direction; The second layer of liquid crystal is used in conjunction with the second transparent electrode to perform phase modulation on linearly polarized light in the first polarization direction; The metasurface quarter-wave plate is used in conjunction with the silicon dioxide dielectric layer and the metal reflective layer to convert linearly polarized light in the first polarization direction into linearly polarized light in the second polarization direction, and to convert linearly polarized light in the second polarization direction into linearly polarized light in the first polarization direction.

2. The silicon-based liquid crystal device according to claim 1, characterized in that, The metasurface quarter-wave plate is composed of a periodically arranged array of cross-shaped silicon nanopillars.

3. The silicon-based liquid crystal device according to claim 2, characterized in that, The thickness of the metal reflective layer is 100~300nm.

4. The silicon-based liquid crystal device according to claim 2, characterized in that, The thickness of the silicon dioxide dielectric layer is 300~500nm.

5. The silicon-based liquid crystal device according to claim 2, characterized in that, The period of the cross-shaped silicon nanopillar array is 700 nm.

6. The silicon-based liquid crystal device according to claim 2, characterized in that, The height of each nanopillar in the cross-shaped silicon nanopillar array is 800~1000nm, its cross-section is cross-shaped, its length is 200~400nm, and its width is 200~400nm.

7. The silicon-based liquid crystal device according to claim 6, characterized in that, The long axis of the cross-section of the nanopillar forms an angle of 45°±5° with the first polarization direction.

8. The silicon-based liquid crystal device according to claim 1, characterized in that, The angle between the alignment planes of the first liquid crystal layer and the second liquid crystal layer is 0°.

9. A polarization-insensitive silicon-based liquid crystal device, characterized in that, It includes a first transparent electrode, a first liquid crystal layer, a second transparent electrode, a second liquid crystal layer, a metasurface quarter-wave plate, a silicon dioxide dielectric layer, a metal reflective layer, and a silicon substrate; The first transparent electrode is disposed on the first surface of the first liquid crystal layer; The second transparent electrode is disposed between the second surface of the first liquid crystal layer and the first surface of the second liquid crystal layer; The second surface of the second layer of liquid crystal is disposed on the first surface of the metasurface quarter-wave plate; The second surface of the metasurface quarter-wave plate is disposed on the first surface of the silicon dioxide dielectric layer; The second surface of the silicon dioxide dielectric layer is disposed on the first surface of the metal reflective layer; The second surface of the metal reflective layer is disposed on the silicon substrate; The first transparent electrode is used to receive incident light and output polarization-converted and phase-modulated beams. The incident light includes linearly polarized light with orthogonal polarization states in a first polarization direction and linearly polarized light with orthogonal polarization states in a second polarization direction. The first layer of liquid crystal is used in conjunction with the first transparent electrode to perform phase modulation on linearly polarized light in the first polarization direction; The second layer of liquid crystal is used in conjunction with the second transparent electrode to perform phase modulation on linearly polarized light in the second polarization direction; The metasurface quarter-wave plate is used in conjunction with the silicon dioxide dielectric layer and the metal reflective layer to convert linearly polarized light in the first polarization direction into linearly polarized light in the second polarization direction, and to convert linearly polarized light in the second polarization direction into linearly polarized light in the first polarization direction.

10. The silicon-based liquid crystal device according to claim 9, characterized in that, The orientation planes of the first liquid crystal layer and the second liquid crystal layer are at an angle of 90°.

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