Self-referenced liquid crystal metasurface tunable device and polarization decoupling method

Abstract

The application discloses a self-referenced liquid crystal metasurface adjustable device and a polarization decoupling method, and relates to the field of liquid crystal controlled metasurfaces. The device comprises a first transparent electrode, a nematic liquid crystal layer, a transparent substrate and a second transparent electrode arranged in sequence from top to bottom; the upper surface of the transparent substrate is provided with a metasurface nano structure immersed in the nematic liquid crystal layer; the metasurface nano structure comprises a plurality of periodically arranged metasurface units, each of which comprises two silicon nanocylinders with the same geometric size; the metasurface unit is used for introducing in-plane symmetry breaking through the relative displacement of the two silicon nanocylinders, realizing polarization decoupling, exciting surface lattice resonance under first polarization incidence as working resonance, and exciting quasi-continuous domain bound state under second polarization incidence as reference resonance. The application can improve the stability and calibrability of the liquid crystal metasurface adjustable device.

Description

Technical Field

[0001] This application relates to the field of liquid crystal tunable metasurface technology, and in particular to a self-referenced liquid crystal metasurface tunable device and polarization decoupling method. Background Technology

[0002] Metasurfaces are a class of two-dimensional optical devices composed of subwavelength artificial micro / nano structural units, capable of modulating the amplitude, phase, polarization, and spectral response of incident light within the subwavelength scale. By rationally designing the geometry, arrangement period, and symmetry of the nanostructures, metasurfaces can excite high-quality factor optical resonance modes such as surface lattice resonance, Fano resonance, and quasi-continuous bound states, thus possessing significant application value in filtering, sensing, optical modulation, beam deflection, polarization control, and integrated photonic devices.

[0003] Liquid crystal materials exhibit significant optical anisotropy and electrically controlled birefringence. By combining liquid crystal materials with metasurfaces, the orientation state of liquid crystal molecules can be modulated by applying an external voltage, thereby altering the effective refractive index of the environment near the metasurface and achieving dynamic adjustment of resonance peak position, transmittance, reflectivity, or phase response. Compared to mechanical tuning, thermal tuning, or phase change material tuning, liquid crystal tuning offers advantages such as low driving voltage, good reversibility, strong control continuity, low cost, and ease of large-area integration. Therefore, tunable devices based on liquid crystal metasurfaces have become an important research direction for tunable nanophotonic devices.

[0004] However, existing tunable liquid crystal metasurface devices typically focus primarily on the tuning capability of a single resonant mode with varying driving voltage, while neglecting the stability and calibrability of the device response under environmental disturbances. For resonant metasurface devices with high quality factors, the resonant peak position is affected not only by the liquid crystal driving voltage but also by factors such as temperature variations, external refractive index changes, humidity variations, encapsulation stress, material aging, and fabrication errors. When the device relies solely on a single resonant peak as the modulation signal, it is difficult to distinguish whether the resonant peak drift originates from liquid crystal electro-tuning or from environmental disturbances or changes in the device's own state. Therefore, in practical applications, single-channel liquid crystal metasurface devices are prone to problems such as misjudgment of modulation state, decreased long-term stability, and insufficient environmental adaptability.

[0005] To address the aforementioned issues, a feasible approach is to introduce a reference resonant channel within the same device, placing the operating resonant channel and the reference resonant channel in the same or similar environment. The operating resonant channel responds to the liquid crystal driving voltage, while the reference resonant channel characterizes environmental disturbances or overall device drift. By comparing the positions, differences, ratios, or relative changes of the two resonant peaks after compensation coefficient correction, the influence of environmental common-mode drift can be mitigated to some extent, achieving self-reference readout and stable modulation. However, achieving a reliable self-reference channel in liquid crystal metasurface devices is not easy. If the reference resonant mode itself is also sensitive to changes in the effective refractive index of the liquid crystal, the reference channel will simultaneously contain voltage tuning information and environmental drift information, making it difficult to serve as a stable environmental reference. Summary of the Invention

[0006] Based on this, it is necessary to provide a self-referenced liquid crystal metasurface tunable device and polarization decoupling method to address the above-mentioned technical problems. By realizing polarization separation between the liquid crystal effective refractive index change-sensitive modulation channel and the liquid crystal effective refractive index change-insensitive / weakly sensitive reference channel in the same liquid crystal metasurface device, the stability and calibrability of the liquid crystal metasurface tunable device can be improved.

[0007] In a first aspect, this application provides a self-referenced liquid crystal metasurface tunable device, comprising:

[0008] The first transparent electrode, the nematic liquid crystal layer, the transparent substrate, and the second transparent electrode are arranged sequentially from top to bottom;

[0009] A metasurface nanostructure immersed in a nematic liquid crystal layer is disposed on the upper surface of a transparent substrate; the metasurface nanostructure includes several periodically arranged metasurface units, each metasurface unit including two silicon nanocylinders of the same geometric size;

[0010] The metasurface unit introduces in-plane symmetry disruption by the relative displacement of two silicon nanocylinders, achieving polarization decoupling. This allows the device to excite surface lattice resonance under the first polarization incident radiation and excite quasi-continuous domain bound states under the second polarization incident radiation.

[0011] Among them, the surface lattice resonance is used as the working resonance, the quasi-continuous domain bound state is used as the reference resonance, and the reference resonance is less sensitive to the change in the effective refractive index of the nematic liquid crystal layer than the working resonance.

[0012] In one embodiment, the first polarization and the second polarization are mutually orthogonal linear polarizations.

[0013] In one embodiment, two silicon nanocylinders in the same metasurface unit are arranged in a non-centrosymmetric manner with respect to the center of the metasurface unit.

[0014] In one embodiment, the relative displacement includes relative displacement along a first direction, relative displacement along a second direction, and a combination of the first and second directions; wherein the first direction is perpendicular to the long axis of the nematic liquid crystal layer in the initial state, and the second direction is parallel to the long axis of the nematic liquid crystal layer in the initial state.

[0015] In one embodiment, the relative displacement includes one of the two silicon nanocylinders being stationary while the other is moving, or the two silicon nanocylinders moving simultaneously but at different speeds or in different directions.

[0016] In one embodiment, when two silicon nanocylinders in the same metasurface unit undergo in-plane relative displacement along a first direction, a non-fully polarized decoupled structure is formed.

[0017] In one embodiment, when two silicon nanocylinders in the same metasurface unit are arranged along a second direction and undergo in-plane relative displacement only along the second direction, a fully polarized decoupled structure is formed.

[0018] Secondly, the present invention provides a polarization decoupling method based on the above-mentioned device, the method comprising:

[0019] A driving voltage is applied to the device through the first and second transparent electrodes, causing the liquid crystal molecules in the nematic liquid crystal layer to undergo an orientation change.

[0020] Displace at least one silicon nanocylinder in the metasurface unit, obtain the transmission spectrum under the first polarization incident, and determine the peak position of the surface lattice resonance, denoted as the first peak position;

[0021] Displace at least one silicon nanocylinder in the metasurface unit, obtain the transmission spectrum under the second polarization incident, and determine the peak position of the excited quasi-continuous domain bound state, denoted as the second peak position;

[0022] A self-reference readout is constructed based on the first and second peak positions to obtain the modulation parameters after self-reference compensation.

[0023] In one embodiment, the self-reference readout includes at least one of the following: peak position difference between the first peak and the second peak, normalized peak position difference, peak position ratio, and weighted peak position difference corrected by a compensation coefficient.

[0024] In one embodiment, the compensation coefficient includes an environmental compensation coefficient, which is pre-calibrated based on at least one disturbance factor among temperature change, humidity change, external refractive index change, packaging stress change, material aging, or incident light source drift.

[0025] The aforementioned self-referenced liquid crystal metasurface tunable device and polarization decoupling method include: a first transparent electrode, a nematic liquid crystal layer, a transparent substrate, and a second transparent electrode arranged sequentially from top to bottom; a metasurface nanostructure immersed in the nematic liquid crystal layer is disposed on the upper surface of the transparent substrate; the metasurface nanostructure includes several periodically arranged metasurface units, each metasurface unit including two silicon nanocylinders of the same geometric size; the metasurface units are used to introduce in-plane symmetry disruption through the relative displacement of the two silicon nanocylinders to achieve polarization decoupling, thereby exciting surface lattice resonance under the first polarization incident light and quasi-continuous domain bound states under the second polarization incident light; wherein, the surface lattice resonance serves as the working resonance, the quasi-continuous domain bound states serve as the reference resonance, and the reference resonance is less sensitive to changes in the effective refractive index of the nematic liquid crystal layer than the working resonance. This invention excites different resonance modes through different polarization channels in the same liquid crystal metasurface device, so that one polarization channel forms a working resonance that is sensitive to changes in the effective refractive index of the liquid crystal, and another polarization channel forms a reference resonance that is insensitive or weakly sensitive to changes in the effective refractive index of the liquid crystal. In this way, while maintaining the electronic tuning capability of the liquid crystal, on-chip self-reference readout and environmental drift compensation are achieved, thereby improving modulation stability. Attached Figure Description

[0026] Figure 1 The following is a schematic diagram of the device structure of a non-fully polarized decoupling structure in one embodiment: (a) is a three-dimensional overall structure diagram, (b) is a cross-sectional view in the xz plane, and (c) is a top view.

[0027] Figure 2 The following is a schematic diagram of the device structure of a fully polarization decoupling structure in one embodiment: (a) is a three-dimensional overall structure diagram, (b) is a cross-sectional view in the xz plane, and (c) is a top view.

[0028] Figure 3 This is a schematic diagram of the transmission spectrum of a non-fully polarized decoupled structure under different effective refractive index states of liquid crystals in one embodiment. (a) is a curve of transmittance in the x direction as a function of wavelength, and (b) is a curve of transmittance in the y direction as a function of wavelength.

[0029] Figure 4 This is a schematic diagram of the transmission spectrum of a fully polarized decoupled structure under different effective refractive index states of liquid crystals in one embodiment. (a) is a curve of transmittance in the x direction as a function of wavelength, and (b) is a curve of transmittance in the y direction as a function of wavelength.

[0030] Figure 5 This is a schematic diagram comparing the normalized electric field amplitude distribution of a non-fully polarized decoupling structure and a fully polarized decoupling structure in one embodiment. (a) corresponds to the non-fully polarized decoupling structure, and (b) corresponds to the fully polarized decoupling structure.

[0031] Figure 6 This is a flowchart illustrating a self-reference readout method in one embodiment.

[0032] Explanation of reference numerals in the attached figures: 10, first transparent electrode; 11, second transparent electrode; 20, nematic liquid crystal layer; 21, silicon nanocylinder; 30, transparent substrate. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0034] This application provides a self-referenced liquid crystal metasurface tunable device that can be widely used in cutting-edge fields such as wavelength division multiplexing optical communication systems, high-resolution spatial light modulators, solid-state lidar optical phased arrays, and high-precision markerless optical sensing.

[0035] like Figure 1 As shown, the device includes: a first transparent electrode 10 and a second transparent electrode 11 disposed at the top and bottom of the device, respectively; a nematic liquid crystal layer 20 disposed below the first transparent electrode 10; a metasurface structure disposed in the nematic liquid crystal layer 20; and a transparent substrate 30 disposed below the nematic liquid crystal layer 20 and the metasurface structure. The metasurface structure includes a plurality of periodically arranged metasurface units, each metasurface unit including two silicon nanocylinders 21, and the two silicon nanocylinders 21 in the same metasurface unit have the same height and the same radius.

[0036] For ease of explanation, the following coordinate system is established in the following embodiments: the plane containing the metasurface unit is... Planar, with the thickness direction of the device as Direction; along the initial major axis direction of the nematic liquid crystal. Direction; voltage application direction along Orientation; the tilt angle of liquid crystal molecules is 0° when no driving voltage is applied, and changes relative to the initial orientation after the driving voltage is applied, and approaches 90° under saturation driving voltage.

[0037] In the aforementioned self-referenced liquid crystal metasurface tunable device, the first transparent electrode 10 and the second transparent electrode 11 are disposed opposite to each other and are used to apply a driving electric field to the nematic liquid crystal layer 20. In a specific embodiment, the first transparent electrode 10 and the second transparent electrode 11 are preferably ITO (Indium Tin Oxide Electrode) electrodes. The thickness of the transparent electrodes can be selected according to the device transmittance, conductivity, and process conditions; the present invention does not limit their specific thickness.

[0038] A transparent substrate 30 is used to support the silicon nanocylinders 21. In one embodiment, the transparent substrate 30 is preferably a glass substrate. The silicon nanocylinders 21 are disposed on the transparent substrate 30 and immersed in the nematic liquid crystal layer 20.

[0039] A nematic liquid crystal layer 20 fills the space between the first transparent electrode 10 and the transparent substrate 30, and at least covers the silicon nanopillars 21, allowing the resonant modes excited by the silicon nanopillars 21 to interact with the anisotropic refractive index environment of the liquid crystal. In one specific embodiment, the ordinary refractive index of the nematic liquid crystal layer 20 is... unusual refractive index The thickness of the nematic liquid crystal layer 20 can be set according to the operating band, driving voltage, and liquid crystal response requirements; the present invention does not limit its specific value.

[0040] The periodicity of the metasurface unit cell satisfies: That is, metasurface units in direction and The period in both directions is From a top-down view, the unit is a square periodic unit.

[0041] Nematic liquid crystals exhibit optical anisotropy, and their effective refractive index depends on the relationship between the electric field direction and the long axis of the liquid crystal. When the electric field component is distributed along the long axis of the liquid crystal, the electric field is extremely sensitive to changes in the effective refractive index of the liquid crystal; when the electric field component is mainly distributed perpendicular to the long axis of the liquid crystal, the sensitivity to changes in the effective refractive index of the liquid crystal is relatively low.

[0042] Based on the above principles, this invention proposes a scheme that differs from conventional methods that break symmetry by changing the dimensions of the two nanopillars. Instead, it introduces in-plane symmetry breaking by altering the relative positions of the two silicon nanopillars 21 within the unit plane during fabrication. This allows for the control of the electric field direction and refractive index sensitivity of different polarization resonance modes while maintaining the geometric consistency of the nanopillars.

[0043] Based on the above scheme, the tunable liquid crystal metasurface device is configured to: excite surface lattice resonance under a first polarized incident radiation, and excite quasi-continuous bound states under a second polarized incident radiation. The first polarization channel serves as the working channel sensitive to changes in the effective refractive index of the liquid crystal, while the second polarization channel serves as a self-reference channel insensitive to / weakly sensitive to changes in the effective refractive index of the liquid crystal, thereby achieving polarization decoupling and self-reference readout of the liquid crystal metasurface device. It should be noted that the sensitivity here emphasizes the comparison between the sensitivity of surface lattice resonance and the excitation of quasi-continuous bound states to changes in the effective refractive index of the liquid crystal, rather than an absolute comparison.

[0044] The first polarization and the second polarization mentioned above are mutually orthogonal linear polarizations. In one specific embodiment, the first polarization is s-polarization and the second polarization is p-polarization, but the present invention is not limited to this specific naming convention.

[0045] In one specific embodiment, the surface lattice resonance excited under the first polarized incident radiation is the operating resonance. The electric field of this resonance mode is at least partially along... The directional distribution means that when the effective refractive index changes, the surface lattice resonance peak in the first polarization channel will drift significantly.

[0046] The quasi-continuous bound-state resonance excited under the second polarization incident radiation serves as the reference resonance. By appropriately selecting the in-plane symmetry breaking method, the electric field of this quasi-continuous bound-state resonance mode can be made to primarily propagate along the plane. The directional distribution of this reference resonance makes it less sensitive to changes in the effective refractive index of the liquid crystal, making it suitable as a self-reference channel.

[0047] It should be noted that quasi-continuous bound state resonance itself is not necessarily immune to changes in the effective refractive index of liquid crystal. The key to this invention lies not in simply introducing quasi-continuous bound states, but in making the quasi-continuous bound states weakly or insensitive to changes in the effective refractive index of liquid crystal through polarization decoupling design. That is, theoretically, any resonance can be used to create a reference channel that is weakly or insensitive to changes in the effective refractive index of liquid crystal through the polarization decoupling design of this invention.

[0048] In one embodiment, the relative displacement of the two silicon nanocylinders 21 can be such that one is stationary while the other moves, or that both move simultaneously but at different speeds or in different directions, thus forming a relative displacement. The direction of the relative displacement includes, but is not limited to, relative displacement along the long axis of the liquid crystal, relative displacement perpendicular to the long axis of the liquid crystal, or a combination of both.

[0049] In a partially polarized decoupled structure, one silicon nanocylinder 21 is located at a first position within the unit plane and remains stationary, while another silicon nanocylinder 21 is displaced in a direction perpendicular to the long axis of the liquid crystal. This structure can excite quasi-continuous bound states under second polarized incident light, but the reference resonance will still experience a certain peak shift with changes in the effective refractive index of the liquid crystal.

[0050] Figure 1 This is a schematic diagram of a device structure with a non-fully polarized decoupling structure. In this embodiment, the two silicon nanocylinders 21 have the same height and the same radius. One silicon nanocylinder 21 is located within the unit plane. , One silicon nanocylinder 21 is fixed at one location, and another silicon nanocylinder 21 is located at the other location. place and along An in-plane displacement occurs in the direction. This results in a symmetry breaking within the plane, allowing the excitation of quasi-continuous bound states under the second polarized incident radiation. However, as... Figure 5 As shown in (a), in this insufficiently polarized decoupling structure, although the second polarization resonance mode is dominated by the electric field component in the y-direction, there is still a certain electric field leakage along the long axis of the liquid crystal. This electric field leakage allows the reference resonance mode to still sense the change in effective refractive index, thus the reference resonance peak changes with the change in the effective refractive index of the liquid crystal as shown in (a). Figure 3 The drift shown in (b) is as follows. In the insufficiently polarized decoupling structure, the first polarization channel can achieve the following: Figure 3 As shown in (a), dynamic tuning is achieved, but strong crosstalk still exists in the second polarization channel. That is, the second polarization channel still has a certain effective refractive index sensitivity; therefore, the reference resonance peak will still drift with changes in the liquid crystal refractive index. Thus, this embodiment illustrates the necessity of polarization decoupling design for forming a stable reference channel.

[0051] In a fully polarized decoupled structure, two silicon nanocylinders 21 are located on the same lateral coordinate line. One silicon nanocylinder 21 is located at a predetermined position and remains stationary, while the other silicon nanocylinder 21 is displaced along the long axis of the liquid crystal. The two silicon nanocylinders 21 do not undergo relative displacement in the direction perpendicular to the long axis of the liquid crystal. This structure allows the change in the effective refractive index of the liquid crystal to be largely ignored for the second polarization resonance mode.

[0052] Figure 2 This is a schematic diagram of the device structure for a fully polarization-decoupled structure. In this embodiment, the two silicon nanocylinders 21 still have the same height and the same radius. Unlike Embodiment 1, one of the silicon nanocylinders 21 is located... , Fixed at one point, another silicon nanocylinder 21 along The direction involves in-plane displacement. For example... Figure 5 As shown in (b), the electric field distribution of the second polarization resonance mode is mainly along the y-direction. Therefore, in a fully polarized decoupled structure, the second polarization mode is insensitive to changes in the liquid crystal refractive index, and thus can be used as a reference resonance that is insensitive / weakly sensitive to changes in the effective refractive index of the liquid crystal. Figure 4 As shown in (a), during the process of the liquid crystal changing from the minimum refractive index to the maximum refractive index, the surface lattice resonance peak under the first polarized incident light exhibits a significant redshift (the resonance peak shifts towards the infrared region in the spectrum), while as Figure 4As shown in (b), the quasi-continuous bound-state resonance peak under the second polarization incident radiation shows almost no drift. Therefore, in the fully polarized decoupling structure, the first polarization channel still maintains significant dynamic tuning capability, while the sensitivity of the second polarization channel to changes in the liquid crystal refractive index is significantly suppressed. Compared to the significant redshift of the second polarization channel in the device with a non-fully polarized decoupling structure, the fully polarized decoupling structure shows almost no drift, indicating that by displacing another silicon nanocylinder 21 along the long axis of the liquid crystal but not in the direction perpendicular to the long axis of the liquid crystal, polarization decoupling between the working channel and the reference channel can be effectively achieved. Therefore, this structure can be considered a preferred embodiment of the present invention.

[0053] Based on a self-referenced liquid crystal metasurface tunable device, embodiments of this application also provide a polarization decoupling method. For example... Figure 6 As shown, the method includes the following steps:

[0054] S1. A driving voltage is applied to the device through the first transparent electrode 10 and the second transparent electrode 11 to cause the liquid crystal molecules in the nematic liquid crystal layer 20 to undergo an orientation change.

[0055] S2. Displace at least one silicon nanocylinder 21 in the metasurface unit, obtain the transmission spectrum under the first polarized incident light, and determine the peak position of the surface lattice resonance, denoted as the first peak position. ;

[0056] S3. Displace at least one silicon nanocylinder 21 in the metasurface unit, obtain the transmission spectrum under the second polarization incident light, and determine the peak position of the excited quasi-continuous domain bound state, denoted as the second peak position. ;

[0057] S4. Construct a self-reference readout based on the first peak position and the second peak position to obtain the modulation parameters after self-reference compensation.

[0058] The self-reference readout includes at least one of the following: peak position difference, normalized peak position difference, peak position ratio, or weighted peak position difference corrected by compensation coefficient.

[0059] In one implementation, the self-reference readout is the peak position difference: .in, This represents the difference between the working resonance peak and the reference resonance peak.

[0060] In one implementation, the self-reference readout is the normalized peak position difference: .in, This represents the normalized self-reference readout.

[0061] In one implementation, the self-reference readout is the weighted peak position difference corrected for compensation coefficients: .in, This represents the modulation parameters after self-reference compensation. This is the environmental compensation coefficient. Pre-calibration can be performed based on at least one of the disturbance factors, such as temperature change, humidity change, external refractive index change, packaging stress change, material aging, or incident light source drift.

[0062] When the environment in which the device operates changes, both the first polarization operating resonance and the second polarization reference resonance may be affected by environmental disturbances, resulting in resonance peak shift. Since the second polarization reference resonance is insensitive to / weakly sensitive to changes in the effective refractive index of the liquid crystal, its peak position change can be used to characterize changes in the device's environment or the overall state of the device. By performing differential, normalized, or weighted differential processing on the peak positions of the first polarization operating resonance and the second polarization reference resonance, the influence of environmental common-mode drift on the determination of the operating resonance modulation state can be reduced.

[0063] It should be noted that this invention does not require the reference resonance to remain constant in the face of all environmental factors. On the contrary, as a self-reference channel, the reference resonance can drift with environmental disturbances, but it should remain insensitive to / weakly sensitive to changes in the effective refractive index of the liquid crystal. Only in this way can the reference resonance reflect environmental drift without significantly incorporating voltage modulation information, thereby facilitating stable self-reference readout.

[0064] In this manner, the first polarization channel is mainly used to respond to changes in the effective refractive index of the liquid crystal, while the second polarization channel is mainly used to provide a reference peak position under the same wafer environment. When the device is subjected to environmental disturbances, both the operating resonance and the reference resonance may drift as a whole; by comparing their relative changes, the influence of environmental common-mode drift on the voltage modulation state judgment can be weakened or eliminated.

[0065] Compared with the prior art, the present invention has the following significant advantages:

[0066] (1) This invention introduces a working resonance and a reference resonance in the same liquid crystal metasurface device. The first polarization channel excites the surface lattice resonance and serves as the working channel sensitive to changes in the effective refractive index of the liquid crystal, while the second polarization channel excites the quasi-continuous domain bound state and serves as the self-reference channel. As a result, the device no longer relies on a single resonance peak to determine the modulation state, but can improve modulation stability through dual-channel relative readout.

[0067] (2) The present invention achieves polarization decoupling by controlling the in-plane displacement of the two silicon nanocylinders. Since the two silicon nanocylinders have the same height and radius, the present invention does not rely on the difference in nanocylinder size to generate mode splitting or asymmetric response, but introduces in-plane symmetry breaking through position displacement, which is beneficial to maintaining the simplicity of structural design and the consistency of processing.

[0068] (3) The present invention can reduce the crosstalk of reference resonance to the change of effective refractive index of liquid crystal. Especially in fully polarized decoupled structures, it significantly reduces the peak position drift caused by the change of effective refractive index of liquid crystal.

[0069] (4) The present invention can improve the environmental adaptability of liquid crystal metasurface tunable devices. By obtaining the working resonance peak position and the reference resonance peak position, and calculating the peak position difference, peak position ratio or weighted peak position difference after compensation coefficient correction, the resonance peak drift caused by factors such as temperature change, humidity change, external refractive index change, packaging stress change, material aging or incident light source drift can be compensated.

[0070] (5) The polarization decoupling method described in this invention has strong design versatility. By changing the in-plane displacement direction and displacement amount of the double cylindrical nanopillars, the coupling strength between different polarization resonance modes and changes in the effective refractive index of the liquid crystal can be controlled, thereby achieving functional separation of the liquid crystal effective refractive index-sensitive working channel and the liquid crystal effective refractive index-insensitive / weakly sensitive reference channel in different working bands, different period sizes, and different liquid crystal material systems.

[0071] (6) This invention is applicable to applications such as tunable filtering, tunable light modulation, spectral detection, environmental self-reference sensing, beam control and integrated photonic devices, and can provide a structural design scheme for liquid crystal metasurface devices that has tunability, stability and self-reference capability.

[0072] It should be understood that the steps involved in the method embodiments described above are not necessarily executed in a sequential order. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps involved in the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but may be executed at different times. The execution order of these steps or stages is not necessarily sequential, but may be performed alternately or in turn with other steps or at least some of the steps or stages in other steps.

[0073] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0074] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A self-referencing liquid crystal metasurface tunable device, characterized in that, include: The first transparent electrode, the nematic liquid crystal layer, the transparent substrate, and the second transparent electrode are arranged sequentially from top to bottom; The upper surface of the transparent substrate is provided with a metasurface nanostructure immersed in the nematic liquid crystal layer; the metasurface nanostructure includes a plurality of periodically arranged metasurface units, each of the metasurface units including two silicon nanocylinders of the same geometric size; The metasurface unit introduces in-plane symmetry disruption through the relative displacement of the two silicon nanocylinders, achieving polarization decoupling. This allows the device to excite surface lattice resonance under a first polarization incident radiation and to excite a quasi-continuous domain bound state under a second polarization incident radiation. The relative displacement occurs when the two silicon nanocylinders in the same metasurface unit are arranged along a second direction, and only in-plane relative displacement occurs along the second direction, with no relative displacement along the first direction, thus forming a fully polarization-decoupled structure. The first direction is perpendicular to the long axis of the nematic liquid crystal layer in the initial state, and the second direction is parallel to the long axis of the nematic liquid crystal layer in the initial state. In this system, the surface lattice resonance serves as the working resonance, the quasi-continuous domain bound state serves as the reference resonance, and the reference resonance is less sensitive to changes in the effective refractive index of the nematic liquid crystal layer than the working resonance. The electric field of the first polarization resonance mode is at least partially distributed along the long axis of the liquid crystal, and the electric field of the second polarization resonance mode is mainly distributed along the direction perpendicular to the long axis of the liquid crystal.

2. The device according to claim 1, characterized in that: The first polarization and the second polarization are mutually orthogonal linear polarizations.

3. The device according to claim 1, characterized in that: The two silicon nanocylinders in the same metasurface unit are arranged in a non-centrosymmetric manner with respect to the center of the metasurface unit.

4. The device of claim 1, wherein: The resonance peak of the surface lattice resonance changes position with the change of the effective refractive index of the liquid crystal, and the peak position change of the resonance peak of the quasi-continuous domain bound state with the change of the effective refractive index of the liquid crystal is smaller than that of the resonance peak of the surface lattice resonance.

5. The device according to claim 1, characterized in that: The relative displacement includes one of the two silicon nanocylinders being stationary while the other is moving, or the two silicon nanocylinders moving simultaneously but at different speeds or in different directions.

6. The device according to claim 4, characterized in that: The nematic liquid crystal layer changes the orientation state of the liquid crystal molecules under the action of the driving voltage, so as to adjust the position of the resonance peak of the surface lattice resonance.

7. The device according to claim 4, characterized in that: The self-reference readout is constructed based on the peak position of the working resonance and the peak position of the reference resonance to obtain the modulation parameters after self-reference compensation.

8. A polarization decoupling method, characterized in that, Based on the device according to any one of claims 1 to 7, the method comprises: A driving voltage is applied to the device through the first transparent electrode and the second transparent electrode, causing the liquid crystal molecules in the nematic liquid crystal layer to undergo an orientation change. Displace at least one of the silicon nanocylinders in the metasurface unit, obtain the transmission spectrum under the first polarized incident light, and determine the peak position of the surface lattice resonance, denoted as the first peak position; Displace at least one of the silicon nanocylinders in the metasurface unit, obtain the transmission spectrum under the second polarization incident, and determine the peak position of the excited quasi-continuous domain bound state, denoted as the second peak position; A self-reference readout is constructed based on the first peak and the second peak to obtain the modulation parameters after self-reference compensation.

9. The method of claim 8, wherein: The self-reference readout includes at least one of the following: peak position difference between the first peak and the second peak, normalized peak position difference, peak position ratio, and weighted peak position difference after compensation coefficient correction.

10. The method of claim 9, wherein: The compensation coefficient includes an environmental compensation coefficient, which is pre-calibrated based on at least one disturbance factor among temperature change, humidity change, external refractive index change, packaging stress change, material aging, or incident light source drift.

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