A pixel structure, a metasurface and a method of controlling a pixel structure

Abstract

The application provides a pixel structure, a metasurface and a method for controlling the pixel structure, wherein the pixel structure comprises: a plurality of phase change units which are identical in structure and arranged in an array; each phase change unit comprises an excitation element and a phase change element, the excitation element is used to apply independent excitation to the phase change element to change the phase change state of the phase change element; the phase change element comprises at least one nanostructure made of a phase change material; the phase change state of the phase change element comprises a crystal state and an amorphous state, and the phase change state of the pixel structure is in one-to-one correspondence with the number of phase change states of the phase change units in the pixel structure. The pixel structure, the metasurface and the method for controlling the pixel structure provided by the embodiment of the application can conveniently realize quasi-continuous adjustment of the pixel structure; and the excitation element can quickly and accurately control the phase change unit to switch between limited phase change states, so that the pixel structure can be quickly and accurately regulated and controlled.

Description

Technical Field

[0001] This invention relates to the field of optical element technology, and more specifically, to a pixel structure, a metasurface, and a method for controlling the pixel structure. Background Technology

[0002] The optical properties of metasurfaces are mainly determined by two factors: ① the geometry and size of the structural units; ② the dielectric constant of the material. Once a metasurface device is fabricated, its geometry and size are difficult to change. Therefore, the optical properties of the device can be controlled or reconstructed by altering the dielectric constant of the material. Phase change materials can change their internal lattice under external stimulation (such as heat, laser, or applied voltage), which can significantly alter their dielectric constant.

[0003] Phase change materials (PCMs) can transform between crystalline and amorphous states, and different PCM states can achieve different modulation effects. For example, when a beam of light is incident on a PCM, if the PCM is in an amorphous state, the emitted left-handed light is deflected to the right; if the PCM is in a crystalline state, the emitted light is deflected to the left, achieving binary modulation. Furthermore, some schemes utilize the partial crystallization characteristic of PCMs, making the transition from amorphous to crystalline a gradual process, thereby achieving continuous control of the reflection phase.

[0004] Existing mature strategies involve switching between the crystalline and amorphous states of phase change materials, but this is only binary modulation (with only two controllable states, also known as phase change states), limiting its applications. On the other hand, although partial crystallization solves the problem of traditional phase change materials having only two controllable states, the degree of crystallinity is difficult to control, resulting in low precision and immature solutions, failing to achieve stable and continuously tunable phase. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a pixel structure, a metasurface, and a method for controlling the pixel structure.

[0006] In a first aspect, embodiments of the present invention provide a pixel structure, comprising: a plurality of phase transition units with identical structures, wherein the plurality of phase transition units are arranged in an array;

[0007] The phase transition unit includes an excitation element and a phase transition element. The excitation element is used to apply independent excitation to the phase transition element to change the phase transition state of the phase transition element.

[0008] The phase change element includes at least one nanostructure made of a phase change material;

[0009] The phase transition state of the phase transition element includes crystalline and amorphous states; there is a one-to-one correspondence between the phase transition state of the pixel structure and the number of phase transition states of the phase transition unit in the pixel structure, and the number of phase transition states includes the number of crystalline phase transition units and / or the number of amorphous phase transition units.

[0010] In one possible implementation, the number of phase change units does not exceed 25.

[0011] In one possible implementation, the excitation element of each phase change unit includes a first electrode and a second electrode spaced apart; the first electrode and the second electrode are electrically connected through an intermediary of the phase change unit.

[0012] A potential difference can be formed between the first electrode and the second electrode, and the temperature of the intermediate component located between the first electrode and the second electrode can be changed by electrothermal conversion, thereby changing the temperature of the phase change element.

[0013] In one possible implementation, the middleware includes a first metallic reflective layer;

[0014] The phase change element is located on the reflective side of the first metal reflective layer;

[0015] The first electrode and the second electrode are electrically connected to the first metal reflective layer, respectively, and are located on both sides of the phase change element.

[0016] In one possible implementation, the phase change unit further includes: a first dielectric layer;

[0017] The first dielectric layer is located between the first metal reflective layer and the phase change element, and abuts against the first metal reflective layer and the phase change element.

[0018] In one possible implementation, the phase change unit further includes: a first insulating layer;

[0019] The first insulating layer is located on one side of the first metal reflective layer, and the phase change element, the first electrode, and the second electrode are all located on the side of the first metal reflective layer away from the first insulating layer.

[0020] In one possible implementation, the phase transition unit further includes a filler that is transparent in the operating wavelength band;

[0021] The filler is filled between the nanostructures of the phase change element.

[0022] In one possible implementation, the middleware includes the phase change element;

[0023] The first electrode is electrically connected to one side of the phase change element, and the second electrode is electrically connected to the other side of the phase change element.

[0024] In one possible implementation, the first electrode has a layered structure and is transparent in the operating wavelength band;

[0025] The phase change element is located on one side of the first electrode; the second electrode is electrically connected to the side of the phase change element away from the first electrode.

[0026] In one possible implementation, the excitation element further includes a connection layer, and the connection layer is transparent in the operating wavelength band;

[0027] The connecting layer is located on the side of the phase change element away from the first electrode and is electrically connected to the phase change element;

[0028] The second electrode is located between the first electrode and the connecting layer, and is electrically connected to the connecting layer.

[0029] In one possible implementation, the first electrodes of the plurality of phase change units are coplanar and are an integral structure.

[0030] In one possible implementation, the phase change unit further includes: a second insulating layer;

[0031] The second insulating layer is located between the first electrode and the second electrode, and abuts against the first electrode and the second electrode.

[0032] In one possible implementation, the pixel structure further includes: a substrate; the substrate is transparent in the operating wavelength band;

[0033] The plurality of phase change units are located on at least one side of the substrate.

[0034] In one possible implementation, the phase change unit further includes: a second metal reflective layer;

[0035] The second metal reflective layer is located on the side of the first electrode away from the phase change element, or it is located between the first electrode and the phase change element;

[0036] The side of the second metal reflective layer closest to the phase change element is the reflective side.

[0037] In one possible implementation, the first electrode includes a third metallic reflective layer;

[0038] The phase change element is located on the reflective side of the third metal reflective layer; the second electrode is electrically connected to the side of the phase change element away from the third metal reflective layer.

[0039] In one possible implementation, the third metal reflective layers of the plurality of phase change units are coplanar and are an integral structure.

[0040] In one possible implementation, the phase change unit further includes: a third insulating layer;

[0041] The third insulating layer is located between the third metal reflective layer and the second electrode, and abuts against the third metal reflective layer and the second electrode.

[0042] In one possible implementation, the phase change unit further includes: a second dielectric layer capable of conducting electricity;

[0043] The second dielectric layer is located between the third metal reflective layer and the phase change element, and abuts against the third metal reflective layer and the phase change element.

[0044] In one possible implementation, one of the first electrode and the second electrode has a fixed potential.

[0045] In one possible implementation, the electrode having the fixed potential is grounded.

[0046] In one possible implementation, the nanostructure is a polarization-independent structure.

[0047] In one possible implementation, the nanostructure includes at least one of the following: a nanocylindrical structure, a hollow nanocylindrical structure, a nanocircular pore structure, a nanoring pore structure, a nanosquare cylindrical structure, a nanosquare pore structure, a nanosquare ring structure, and a nanosquare ring pore structure.

[0048] Secondly, embodiments of the present invention also provide a metasurface comprising a plurality of pixel structures as described above, wherein the plurality of pixel structures are arranged in an array.

[0049] Thirdly, embodiments of the invention also provide a method for controlling the pixel structure as described above, comprising:

[0050] A one-to-one correspondence is predetermined between the number of phase transition states of phase transition units in the pixel structure and the phase transition states of the pixel structure;

[0051] Determine the phase transition state of the pixel structure corresponding to the current control phase, and determine the target number of phase transition states of the phase transition unit corresponding to the current control phase based on the correspondence.

[0052] The electrodes of at least some phase transition units are individually controlled to change the phase transition state of the at least some phase transition units, and the number of phase transition states of the controlled phase transition units is consistent with the target number of phase transition states.

[0053] In the solution provided by the first aspect of the present invention, the pixel structure includes multiple phase transition units with identical structures. Each phase transition unit is provided with an independent excitation element, which can independently excite the nanostructure made of phase transition material, thereby independently controlling and changing the phase transition state of each phase transition unit, and thus adjusting the overall phase transition state of the pixel structure. Furthermore, all phase transition units have the same structure. The phase transition units control the propagation phase and are not sensitive to the polarization direction of light. The equivalent refractive index of the pixel structure as a whole is only related to the number of phase transition units with different phase transition states and is independent of the arrangement. Therefore, by adjusting the phase transition states of phase transition units at different positions of the pixel structure, the phase transition state of the pixel structure can be adjusted while only focusing on the quantity. Even when the types of phase transition states of the phase transition units are limited, quasi-continuous tunability of the pixel structure can be easily achieved. Moreover, the excitation element can quickly and accurately control the phase transition units to switch between a limited number of phase transition states, thereby enabling rapid and accurate control of the pixel structure.

[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This diagram illustrates a pixel structure provided in an embodiment of the present invention.

[0057] Figure 2 A schematic diagram of the phase transition state of the 2×2 pixel structure provided in an embodiment of the present invention is shown;

[0058] Figure 3 This diagram illustrates the phase transition state of the 3×3 pixel structure provided in an embodiment of the present invention.

[0059] Figure 4 This invention provides a schematic diagram illustrating various arrangement methods corresponding to a phase transition state of the pixel structure.

[0060] Figure 5 This diagram illustrates the control wiring of the pixel structure provided in an embodiment of the present invention.

[0061] Figure 6 A schematic diagram of the first structure of the phase change unit provided in an embodiment of the present invention is shown;

[0062] Figure 7A A schematic diagram of the second structure of the phase change unit provided in an embodiment of the present invention is shown;

[0063] Figure 7B A schematic diagram of the third structure of the phase change unit provided in an embodiment of the present invention is shown;

[0064] Figure 8A A schematic diagram of the fourth structure of the phase change unit provided in an embodiment of the present invention is shown;

[0065] Figure 8B A fifth structural schematic diagram of the phase change unit provided in an embodiment of the present invention is shown;

[0066] Figure 8C A sixth structural schematic diagram of the phase change unit provided in an embodiment of the present invention is shown;

[0067] Figure 9A A seventh structural schematic diagram of the phase change unit provided in an embodiment of the present invention is shown;

[0068] Figure 9B The eighth structural schematic diagram of the phase change unit provided in the embodiment of the present invention is shown;

[0069] Figure 10 A schematic diagram of phase modulation of the pixel structure provided in an embodiment of the present invention is shown.

[0070] icon:

[0071] 1-Phase change unit, 1a-Amorphous phase change unit, 1c-Crystallic phase change unit, 10-Excitation element, 101-First electrode, 102-Second electrode, 103 Connecting layer, 20-Phase change element, 201-Nanostructure, 301-First metal reflective layer, 302-Second metal reflective layer, 303-Third metal reflective layer, 401-First dielectric layer, 402-Second dielectric layer, 501-First insulating layer, 502-Second insulating layer, 503-Third insulating layer, 504-Fourth insulating layer, 60-Fill, 70-Substrate. Detailed Implementation

[0072] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0073] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0074] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] This invention provides a pixel structure, see [link to relevant documentation]. Figure 1 As shown, the pixel structure includes multiple phase transition units 1 with the same structure, and the multiple phase transition units 1 are arranged in an array. Figure 1 In this pixel structure, there are four phase transition units 1, which are arranged in a 2×2 array.

[0076] like Figure 1 As shown, the phase change unit 1 includes an excitation element 10 and a phase change element 20, for example, the excitation element 10 and the phase change element 20 are disposed on a substrate 70. The excitation element 10 is used to apply independent excitation to the phase change element 20 to change the phase change state of the phase change element 20; the phase change state of the phase change element 20 includes a crystalline state and an amorphous state; wherein, the phase change element 20 includes at least one nanostructure 201 made of a phase change material.

[0077] In this embodiment of the invention, the pixel structure is a superpixel comprising multiple phase-change units 1, each of which can be independently controlled. Specifically, as shown... Figure 1 As shown, the phase change unit 1 is a metasurface structure containing at least one nanostructure 201 made of a phase change material. When the excitation element 10 applies excitation to the nanostructure 201, the phase change state of the nanostructure 201 can be controlled and changed by utilizing the property that the phase change material can change its phase change state under excitation, that is, the phase change state of the phase change unit 1 can be changed. Furthermore, the excitation element 10 in each phase change unit 1 is used to independently apply excitation to the phase change element 20 (such as the nanostructure 201), that is, each phase change unit 1 is independently excited, thereby allowing independent control of each phase change unit 1. Figure 1 The excitation element 10 is schematically shown in a spherical shape next to the nanostructure 201, but... Figure 1 This is merely a schematic diagram of the pixel structure and is not intended to define the position and shape of the excitation element 10 and the nanostructure 201.

[0078] In this embodiment of the invention, each phase transition unit 1 has multiple controllable phase transition states, referred to simply as phase transition states; and each phase transition state of phase transition unit 1 is a precisely controllable phase transition state. For example, since the crystalline and amorphous states of the phase transition material can be precisely controlled, in this embodiment, both the crystalline and amorphous states are set as the phase transition states of phase transition unit 1. By controlling the magnitude of the excitation applied by excitation element 10 to phase transition element 20, or whether excitation is applied at all, the phase transition state of each phase transition unit 1 in the pixel structure can be controlled, so that the pixel structure as a whole has different phase transition states. For example, under the action of excitation and trigger 10, each phase transition unit 1 can switch between crystalline and amorphous states. For a pixel structure containing n phase transition units 1, it has n+1 phase transition states, and each phase transition state corresponds to a phase. That is, when phase transition unit 1 is binary controlled (it only has crystalline and amorphous states), the pixel structure can also have more phase transition states, thereby achieving multi-state tunability of the pixel structure, which is referred to as "quasi-continuous tunability" in this embodiment. As the number of phase transition units 1 contained in the pixel structure increases, the pixel structure has more phase transition states.

[0079] For example, see Figure 2 As shown, the pixel structure includes four phase transition units 1, arranged in a 2×2 configuration. Each phase transition unit 1 has two states: crystalline and amorphous. It can switch between the crystalline and amorphous states by controlling its respective excitation element 10. In this embodiment, 1c represents the crystalline phase transition unit, and 1a represents the amorphous phase transition unit. The pixel structure includes five phase transition states: A, B, C, D, and E. Figure 2 And the following Figures 3-5 Amorphous phase transition unit 1a is represented by a white box, and crystalline phase transition unit 1c is represented by a gray box. For example... Figure 2 As shown, when all four phase transition units 1 of the pixel structure are crystalline, the phase transition state of the pixel structure is phase transition state A. In this embodiment, the number of crystalline and amorphous phase transition units is used to represent the phase transition state of the pixel structure; for example, Figure 2 The five phase transition states A, B, C, D, and E of the pixel structure shown are 0a4c, 1a3c, 2a2c, 3a1c, and 4a0c, where a represents the amorphous state and c represents the crystalline state.

[0080] For example, see Figure 3As shown, the pixel structure includes nine phase transition units 1, arranged in a 3×3 configuration. Each phase transition unit 1 has two states: crystalline and amorphous. Figure 3 The ten phase transition states of the pixel structure are shown, in order: 0a9c, 1a8c, 2a7c, 3a6c, 4a5c, 5a4c, 6a3c, 7a2c, 8a1c and 9a0c.

[0081] In this embodiment of the invention, the phase transition state of a pixel structure is related to the number of phase transition units of different phase transition states it contains, for example, the number of crystalline phase transition units and the number of amorphous phase transition units. For ease of description, this embodiment refers to the "number of crystalline phase transition units and / or the number of amorphous phase transition units" as the "number of phase transition states." For example, the number of phase transition states can be the number of crystalline phase transition units, or it can be the number of amorphous phase transition units, or it can be both the number of crystalline phase transition units and the number of amorphous phase transition units, that is, the number of phase transition states includes the number of phase transition units of both phase transition states. Here, a crystalline phase transition unit refers to a phase transition unit that is currently in a crystalline state, and an amorphous phase transition unit refers to a phase transition unit that is currently in an amorphous state.

[0082] There is a one-to-one correspondence between the number of phase transition states of the phase transition unit and the phase transition states of the pixel structure. The correspondence between the two is one-to-one, that is, different numbers of phase transition states correspond to different phase transition states of the pixel structure. Since there can be multiple phase transition states, the pixel structure can have more phase transition states, which can achieve quasi-continuous adjustability.

[0083] Specifically, in this embodiment of the invention, each phase transition unit 1 is used to regulate the propagation phase of light. The phase transition unit 1 (or pixel structure) is insensitive to the polarization direction of light. Furthermore, the multiple phase transition units 1 contained in the pixel structure have the same structure, so the phase transition state of the pixel structure is only related to the number of phase transition units 1 with different phase transition states contained therein, and is independent of the arrangement of the phase transition units 1 with different phase transition states. Optionally, the nanostructure 201 is a polarization-independent structure to be able to regulate the propagation phase of light. For example, the nanostructure 201 includes at least one of the following: a nanocylindrical structure, a hollow nanopillar structure, a nanocircular hole structure, a nanoring hole structure, a nanosquare pillar structure, a nanosquare hole structure, a nanosquare ring structure, and a nanosquare ring hole structure.

[0084] For example, with Figure 3Taking the pixel structure shown as an example, if the phase transition state of the pixel structure is 3a6c, it contains 3 amorphous phase transition units 1a and 6 crystalline phase transition units 1c. This pixel structure can form a total of C(9,3) = 84 arrangements. Since some arrangements correspond to the same arrangement after rotation or mirroring, in this embodiment of the invention, these arrangements are essentially equivalent. See also: [link to embodiment of the invention] Figure 4 As shown, there are 14 possible arrangements of phase transition state 3a6c. Although these 14 arrangements are different from each other, the phase transition state of the corresponding pixel structure is the same, which is 3a6c.

[0085] In this embodiment of the invention, when it is necessary to adjust the phase transition state of the pixel structure, the excitation element 10 in each phase transition unit 1 is controlled to apply excitation to the phase transition element 20 (if the excitation element 10 is not working, it is equivalent to applying zero excitation). This allows the number of phase transition units 1 with different phase transition states in the pixel structure to be adjusted as needed, thereby achieving adjustment of the phase transition state of the pixel structure. Because the phase transition state of the phase transition unit 1 can be quickly and accurately adjusted, the phase transition state of the entire pixel structure can be quickly and accurately adjusted; and because the number of phase transition states in the pixel structure is relatively large, quasi-continuous adjustability can be achieved. For example, this pixel structure is suitable for high-speed, high-efficiency wavefront modulation and has significant potential applications in all-solid-state lidar and other fields.

[0086] In some embodiments, the phase change material used to fabricate the nanostructure 201 can be germanium antimony telluride (Ge X SB Y TE Z Germanium telluride (Ge) X TE Y Antimony telluride (Sb) X TE Y ), silver antimony telluride (Ag) X SB Y TE Z For example, the phase change material is GST (Ge2SB2TE5). Normally, GST is amorphous; after applying excitation to GST (e.g., heating), the amorphous GST will transform into a crystalline state, achieving a rapid amorphous-to-crystalline transition. Furthermore, after crystalline GST is heated above its melting point, it can be rapidly cooled back into an amorphous state; the entire cooling process can be completed rapidly within 10 ns, thus also achieving a rapid crystalline-to-amorphous transition. In this embodiment of the invention, if a nanostructure 201 is fabricated using GST, the temperature of the nanostructure 201 can be changed by the excitation element 10, thereby achieving a crystalline state. Rapid transitions between amorphous states enable rapid modulation of the phase transition states of the pixel structure.

[0087] The pixel structure provided in this embodiment of the invention includes multiple phase transition units 1 with identical structures. Each phase transition unit is provided with an independent excitation element 10, which can independently excite the nanostructure 201 made of phase transition material, thereby independently controlling and changing the phase transition state of each phase transition unit 1, and thus adjusting the overall phase transition state of the pixel structure. Furthermore, all phase transition units 1 have the same structure. The phase transition unit 1 controls the propagation phase and is not sensitive to the polarization direction of light. The equivalent refractive index of the pixel structure as a whole is only related to the number of phase transition units 1 with different phase transition states, and is independent of the arrangement. Therefore, by adjusting the phase transition states of phase transition units 1 at different positions of the pixel structure, the phase transition state of the pixel structure can be adjusted while only focusing on the quantity. Even when the types of phase transition states of phase transition units 1 are limited, quasi-continuous tunability of the pixel structure can be easily achieved. Moreover, the excitation element 10 can quickly and accurately control the phase transition units 1 to switch between a limited number of phase transition states, thereby enabling rapid and accurate control of the pixel structure.

[0088] Optionally, if the pixel structure contains a large number of phase transition units 1, as mentioned above, the number of tunable phase transition states in the middle of the pixel structure is also large, making it closer to continuous tunability. However, a large number of phase transition units 1 will lead to a larger period of the pixel structure (e.g., a larger radius), and when incident light is incident on the large pixel structure, it is easy to generate higher-order diffraction, resulting in the pixel structure being too inefficient to be used. In this embodiment of the invention, in order to effectively avoid generating higher-order diffraction, the number of phase transition units 1 contained in the pixel structure does not exceed 25. For example, the number of phase transition units 1 is 4 (2×2 array) or 9 (3×3 array), etc.

[0089] In some embodiments, the excitation element 10 applies excitation to the phase change element 20 in an electrically controlled manner, heating the phase change element 20 through electrothermal conversion, thereby changing the temperature of the phase change element 20. Specifically, Figure 6 A schematic diagram of a phase change unit 1 is shown. The phase change unit 1 includes an intermediate component for conducting electricity and heating. Each excitation element 10 of the phase change unit 1 includes a first electrode 101 and a second electrode 102 spaced apart, meaning the first electrode 101 and the second electrode 102 are not directly electrically connected to avoid short circuits. The first electrode 101 and the second electrode 102 are electrically connected through the intermediate component of the phase change unit 1. A potential difference can be formed between the first electrode 101 and the second electrode 102, and the temperature of the intermediate component located between the first electrode 101 and the second electrode 102 can be changed by electrothermal conversion, thereby changing the temperature of the phase change element 20. At least one electrode (first electrode 101 or second electrode 102) in different phase change units 1 is independently controlled, allowing excitation to be applied to different phase change units 1 respectively.

[0090] In this embodiment of the invention, the phase change unit 1 includes an intermediate component capable of conducting electricity and heating. This intermediate component is located between the first electrode 101 and the second electrode 102 and is electrically connected to both electrodes (i.e., the first electrode 101 and the second electrode 102). Furthermore, by applying different voltages to the first electrode 101 and the second electrode 102, a potential difference is generated between them. Current flows through the intermediate component, and electrothermal conversion occurs, thereby changing the temperature of the phase change element 20 in the phase change unit 1. Since the phase change material itself is also conductive, the phase change element 20 can be directly used as the intermediate component; alternatively, other intermediate components can be used to achieve conductivity. To effectively heat the phase change element 20, the intermediate component abuts against the phase change element 20.

[0091] For example, see Figure 6 As shown, the phase change element 20 is an intermediate component. The first electrode 101 and the second electrode 102 are respectively disposed on both sides of the nanostructure 201 of the phase change element 20 (e.g., Figure 6 (The top and bottom sides of the nanostructure 201). The voltage of the first electrode 101 is V1, and the voltage of the second electrode is V2. A potential difference ΔV = V1 - V2 can be formed between them. When current flows through the nanostructure 201, the nanostructure 201 generates heat, thereby changing its own temperature and achieving a crystalline state. Rapid transition between amorphous states. Furthermore, the phase transition unit 1 can be either transmissive or reflective; this embodiment does not limit this. Figure 6 The diagram shows a transmission phase change unit. The incident light A is modulated by the phase change unit 1, and the modulated light B is emitted. The light B is the transmitted light.

[0092] Optionally, for ease of wiring, one of the first electrode 101 and the second electrode 102 has a fixed potential. That is, by controlling the voltage of the other electrode, the potential difference between them can be controlled, thereby controlling the magnitude of the excitation. For example, if the potential of the first electrode 101 is fixed, then only the voltage of the second electrode 102 needs to be controlled. Optionally, the fixed potential corresponding to all phase change units 1 is the same; for example, the electrode with the fixed potential is grounded to facilitate wiring.

[0093] For example, one wiring method for a pixel structure can be found in [reference needed]. Figure 5 As shown; Figure 5 In this pixel structure, there are nine phase-change units 1 arranged in a 3×3 pattern. In each phase-change unit 1, one electrode (e.g., the first electrode 101) is grounded, and the other electrode (e.g., the second electrode 102) is connected to a control line, thereby controlling the voltage of the electrode. The electrodes with the same fixed potential can be a single integrated structure for ease of fabrication.

[0094] In one possible implementation, the phase change unit 1 is a reflective phase change unit, i.e., it is used to reflect light. In this embodiment of the invention, the reflection of light can be achieved based on a metal reflective layer, and since the metal reflective layer is made of a conductive metal, it can be used as an intermediate component; for example, the metal reflective layer is made of gold, silver, copper, aluminum, or their alloys. See also Figure 7A The intermediate component of the phase change unit 1 includes a first metal reflective layer 301. The phase change element 20 is located on the reflective side of the first metal reflective layer 301; the first electrode 101 and the second electrode 102 are electrically connected to the first metal reflective layer 301 and are located on both sides of the phase change element 20.

[0095] In this embodiment of the invention, the first metal reflective layer 301 has a reflective side capable of reflecting light, and the phase change element 20 is located on this reflective side to modulate the reflected light. The phase change element 20 may comprise a nanostructure 201, or, as... Figure 2 and Figure 6 As shown, the phase change element 20 may also include multiple nanostructures 201, which are arranged periodically. For ease of description, this embodiment uses a phase change element 20 containing one nanostructure 201 as an example. Figure 7A The phase change element 20 is represented by nanostructure 201. The first electrode 101 and the second electrode 102, which are electrically connected to the first metal reflective layer 301, are located on both sides of the phase change element 20, so that when the first metal reflective layer 301 is energized, the part closest to the nanostructure 201 can generate heat, thereby effectively heating the nanostructure 201.

[0096] To prevent leakage of phase change unit 1, such as Figure 7A As shown, the phase change unit 1 further includes a first insulating layer 501. The first insulating layer 501 is located on one side of the first metal reflective layer 301, and the phase change element 20, the first electrode 101, and the second electrode 102 are all located on the side of the first metal reflective layer 301 away from the first insulating layer 501.

[0097] Optionally, the nanostructure 201 can be directly disposed on the first metal reflective layer 301, i.e., the two are in contact. Alternatively, see... Figure 7AAs shown, the phase change unit 1 further includes a first dielectric layer 401. The first dielectric layer 401 is located between the first metal reflective layer 301 and the phase change element 20, and abuts against the first metal reflective layer 301 and the phase change element 20. The first dielectric layer 401 abuts against the nanostructure 201, and the difference between the refractive index of the first dielectric layer 401 and the refractive index of the nanostructure 201 (or the equivalent refractive index of the nanostructure 201) is less than or equal to a preset threshold, for example, the preset threshold is 1 or 0.5, so that the refractive index of the nanostructure 201 matches the refractive index of the first dielectric layer 401, thereby improving the transmittance of the nanostructure 201. For example, the thickness of the metal reflective layer (e.g., the first metal reflective layer 301) can be 100 nm to 100 μm, and the thickness of the first dielectric layer 401 can be 30 nm to 1000 nm.

[0098] The first dielectric layer 401 is transparent in the operating wavelength range, for example, it can transmit visible light and infrared light. For example, the material of the first dielectric layer 401 can be quartz glass; or, the material of the first dielectric layer 401 can be a conductive and transparent material, such as indium tin oxide (ITO). In this case, the first dielectric layer 401 can also be connected to two electrodes, meaning that the first dielectric layer 401 can also be electrically energized and generate heat. Its structure can be found in [reference needed]. Figure 7B As shown.

[0099] Optionally, see Figure 7B As shown, the phase change unit 1 further includes a filler 60, which is transparent in the operating wavelength band; the filler 60 is filled between the nanostructures 201 of the phase change element 20. In this embodiment of the invention, a transparent material, namely the filler 60, is filled around the nanostructures 201; the filler 60 has high transmittance in the operating wavelength band, and the difference between the refractive index of the filler 60 and the refractive index of the phase change material is not less than 0.5, so as to ensure the modulation effect of the nanostructures 201.

[0100] In this embodiment of the invention, if the initial state of the nanostructure 201 is amorphous, after light A is incident on the reflective phase transition unit 1, the nanostructure 201 can modulate the phase of light A, and... After reflection and emission; if the electrode applies a voltage excitation to the first metal reflective layer 301, the first metal reflective layer 301 becomes conductive and heated, and the heat is conducted to the nanostructure 201, causing the phase change material to undergo a phase change from an amorphous state to a crystalline state. At this time, the incident light ray A, after being modulated by the nanostructure 201, has a phase change of [missing information]. This allows for different modulation effects. Those skilled in the art will understand that the above description only illustrates the working principle of one phase transition unit 1. The working principle is similar for pixel structures containing multiple phase transition units 1, and will not be elaborated here.

[0101] In one possible implementation, the phase change element 20 can be used directly to achieve both electrical conductivity and heating; that is, the intermediate component includes the phase change element 20. See also Figure 6 or Figure 8A As shown, the first electrode 101 is electrically connected to one side of the phase change element 20, and the second electrode 102 is electrically connected to the other side of the phase change element 20. Figure 6 and Figure 8A As shown, the first electrode 101 is electrically connected to the lower side of the nanostructure 201, and the second electrode 102 is electrically connected to the upper side of the nanostructure 201. Under the action of the two electrodes, the nanostructure 201, made of phase change material, directly conducts electricity and generates heat, thereby achieving a phase change.

[0102] Optionally, such as Figure 8A As shown, the first electrode 101 has a layered structure, allowing the phase change element 20 to be directly disposed on one side of the first electrode 101; the first electrode 101 is transparent in the operating wavelength range, avoiding a reduction in light transmittance; the second electrode 102 is electrically connected to the side of the phase change element 20 away from the first electrode 101, for example, as... Figure 8A As shown, the second electrode 102 is electrically connected to the upper side of the nanostructure 201.

[0103] The second electrode 102 can be directly electrically connected to the nanostructure 201; or, as... Figure 8A As shown, the excitation element 10 further includes a connecting layer 103, which is transparent in the operating wavelength range. The connecting layer 103 is located on the side of the phase change element 20 away from the first electrode 101 and is electrically connected to the phase change element 20; the second electrode 102 is located between the first electrode 101 and the connecting layer 103 and is electrically connected to the connecting layer 103. In this embodiment of the invention, both the layered first electrode 101 and the connecting layer 103 are made of conductive and transparent materials, for example, they can be made of ITO.

[0104] For example, to avoid leakage between the spaced-apart first electrode 101 and second electrode 102, see [reference needed]. Figure 8A As shown, the phase change unit 1 further includes a second insulating layer 502; the second insulating layer 502 is located between the first electrode 101 and the second electrode 102, and abuts against the first electrode 101 and the second electrode 102. Optionally, the phase change unit 1 may also include a fourth insulating layer 504 arranged parallel to the nanostructure 201, which can achieve insulation while supporting part of the electrodes. Figure 8A As shown, the fourth insulating layer 504 can serve as a support for the connecting layer 103.

[0105] Optionally, if the first electrode 101 has a layered structure, it can be configured as an electrode with a fixed potential. In this embodiment of the invention, the first electrodes 101 of the plurality of phase change units 1 are coplanar and have an integral structure, that is, the first electrodes 101 of the plurality of phase change units 1 are an integral electrode layer, which is convenient for processing. For example, the first electrode 101 of this integral structure is grounded.

[0106] Alternatively, in conjunction with the above Figure 7B The phase transition unit shown is similar; see [link to relevant documentation]. Figure 8B As shown, the phase change unit 1 may also include: a filler 60, which is transparent in the operating wavelength band; the filler 60 is filled between the nanostructures 201 of the phase change element 20. In this embodiment of the invention, a transparent material, namely the filler 60, is filled around the nanostructures 201; the filler 60 has high transmittance in the operating wavelength band, and the difference between the refractive index of the filler 60 and the refractive index of the phase change material is not less than 0.5, so as to ensure the modulation effect of the nanostructures 201.

[0107] When the electrode is energized to the phase change element 20, the phase change unit 1 can be a transmission-type phase change unit. For example... Figure 8A and Figure 8B As shown, light ray A enters phase change unit 1, which modulates the phase of light ray A and emits modulated light ray B, which is transmitted light. Alternatively, a metal reflective layer can be provided for phase change unit 1 to form a reflective phase change unit.

[0108] Optionally, see Figure 8C As shown, the phase change unit 1 further includes a second metal reflective layer 302. The second metal reflective layer 302 is located on the side of the first electrode 101 away from the phase change element 20, or between the first electrode 101 and the phase change element 20; the side of the second metal reflective layer 302 closest to the phase change element 20 is the reflective side.

[0109] In this embodiment of the invention, a second metal reflective layer 302 is provided that abuts against the first electrode 101, thereby achieving light reflection. Wherein, as... Figure 8C As shown, the second metal reflective layer 302 is located on the side of the first electrode 101 away from the phase change element 20, that is, the second metal reflective layer 302 and the phase change element 20 are located on opposite sides of the first electrode 101. Alternatively, the second metal reflective layer 302 can also be located between the first electrode 101 and the phase change element 20, and abut against the first electrode 101. By utilizing the conductive properties of metal, power can also be supplied to the nanostructure 201.

[0110] Alternatively, for Figure 8CIn the embodiment shown, since both the second metal reflective layer 302 and the first electrode 101 can conduct electricity, the removal of... Figure 8C In the case of the first electrode 101, a phase-change unit capable of reflecting light can also be realized, that is, the second metal reflective layer 302 can be directly used as the first electrode 101. Therefore, the metal reflective layer can be directly used as one of the electrodes. See Figure 9A As shown, the first electrode 101 includes a third metal reflective layer 303. Figure 9A The first electrode 101 is represented by the third metal reflective layer 303. The phase change element 20 is located on the reflective side of the third metal reflective layer 303; the second electrode 102 is electrically connected to the side of the phase change element 20 away from the third metal reflective layer 303.

[0111] In this embodiment of the invention, the working principle of the phase change unit 1 is the same as described above. Figure 8C The principle of the phase transition unit 1 shown is the same. The third metal reflective layer 303 is the same as described above. Figure 8C The second metal reflective layer 302 in the illustrated embodiment is essentially the same. For example, both are similar to the first metal reflective layer 301, and can be layered structures made of metals such as gold and silver.

[0112] Optionally, with the above Figure 7A The phase change unit shown includes a first insulating layer 501, similar to [see also...] Figure 9A As shown, the phase change unit 1 further includes a third insulating layer 503; the third insulating layer 503 is located between the third metal reflective layer 303 and the second electrode 102, and abuts against the third metal reflective layer 303 and the second electrode 102. By providing the third insulating layer 503, leakage current can be effectively prevented.

[0113] Optionally, with the above Figure 7A The phase change unit shown includes a first dielectric layer 401, similar to [see also...] Figure 9A As shown, the phase change unit 1 further includes a second dielectric layer 402 capable of conducting electricity. The second dielectric layer 402 is located between the third metal reflective layer 303 and the phase change element 20, and abuts against the third metal reflective layer 303 and the phase change element 20. The second dielectric layer 402 is transparent in the operating wavelength range, for example, it can transmit visible light and infrared light. For example, the material of the second dielectric layer 402 can be quartz glass; or, the material of the second dielectric layer 402 can be a conductive and transparent material, such as indium tin oxide (ITO).

[0114] Optionally, with the above Figure 8A The phase change unit shown includes a second insulating layer 502 and a fourth insulating layer 504, similar to those described above. Figure 9AAs shown, the phase change unit may also include a second insulating layer 502 and a fourth insulating layer 504 to effectively prevent leakage between the first electrode 101 and the second electrode 102.

[0115] Optionally, since the third metal reflective layer 303 has a layered structure, it can be set to a fixed potential, for example, grounded. In this case, the third metal reflective layers 303 of the multiple phase change units 1 are coplanar and have an integral structure, which facilitates the overall fabrication and processing of the pixel structure.

[0116] Optionally, see Figure 9B As shown, the phase change unit 1 further includes a filler 60, which is transparent in the operating wavelength band; the filler 60 is filled between the nanostructures 201 of the phase change element 20. In this embodiment of the invention, a transparent material, namely the filler 60, is filled around the nanostructures 201; the filler 60 has high transmittance in the operating wavelength band, and the difference between the refractive index of the filler 60 and the refractive index of the phase change material is not less than 0.5, so as to ensure the modulation effect of the nanostructures 201.

[0117] Based on the above embodiments, such as Figure 1 As shown, the pixel structure also includes a substrate 70. All phase transition units 1 can share the same substrate 70, meaning that multiple phase transition units 1 are arranged in an array on one side of the substrate 70. The substrate 70 is located on the outermost side of the phase transition units 1; as shown... Figure 6 As shown, the lower side of the first electrode 101 and the upper side of the second electrode 102 are the outermost sides of the phase change unit 1, and the substrate 70 can be disposed on the lower side of the first electrode 101 (e.g., Figure 6 (As shown), it can also be set on the upper side of the second electrode 102.

[0118] Optionally, to avoid the substrate 70 affecting the modulation of light incident on the phase change unit 1, the substrate 70 is transparent in the operating wavelength range. For example, if the phase change unit 1 is a transmissive phase change unit, or if the substrate 70 is located on the side of the nanostructure 201 away from the metal reflective layer, the substrate 70 needs to be a transparent substrate; for example, the substrate 70 can be made of silicon, quartz or other glass materials.

[0119] The modulation effect of this pixel structure will be described in detail below through an example.

[0120] In this embodiment of the invention, the pixel structure comprises four phase transition units 1 arranged in a 2×2 pattern. Each phase transition unit 1 is transmissive and contains one nanostructure 201, which is a columnar structure and can be simply referred to as a nanopillar. The period of the nanostructure 201 is 500 nm, and the height of the nanostructure 201 is 1200 nm. The phase modulation of the pixel structure differs for nanostructures 201 with different diameters. The relationship between the phase modulation (rad) of the pixel structure and the diameter (nm) of the nanostructure 201 under different combinations of crystalline and amorphous phase transition units 1 is described in [reference needed]. Figure 10 As shown. Figure 10 In the diagram, 0a4c, 1a3c, 2a2c, 3a1c, and 4a0c represent the five phase transition states of the pixel structure, and their corresponding phase modulations are as follows: Figure 10 As shown. The 2×2 pixel structure can modulate 5 phases, and is composed of... Figure 10 It can be seen that this pixel structure has a maximum phase modulation capability of 1.5π.

[0121] Based on the same inventive concept, embodiments of the present invention also provide a metasurface, which includes a plurality of pixel structures as provided in any of the above embodiments, and the plurality of pixel structures are arranged in an array. Each pixel structure in the metasurface can achieve polymorphic quasi-continuous tunability and can be applied to multiple scenarios. For example, the metasurface can be applied to all-solid-state lidar, color displays, wavefront correctors, spatial light modulators, beamformers, etc.

[0122] This invention also provides a method for controlling the pixel structure provided in any of the above embodiments, the method comprising:

[0123] Step A1: Predetermine the one-to-one correspondence between the number of phase transition states of phase transition units in the pixel structure and the phase transition states of the pixel structure.

[0124] As described above, in this embodiment of the invention, there is a one-to-one correspondence between the number of phase transition states of the phase transition unit and the phase transition states of the pixel structure. That is, different numbers of phase transition states correspond to different phase transition states of the pixel structure, enabling the pixel structure to have more phase transition states and achieve quasi-continuous adjustability. Furthermore, this correspondence can be predetermined. For example, after determining the structure of the phase transition unit, the phase transition states of the pixel structure corresponding to different numbers of phase transition states can be determined through theoretical derivation or simulation. For example, with... Figure 10 Taking the illustrated embodiment as an example, the diameter of the nanostructure in the phase change unit is fixed, based on... Figure 10 This allows us to determine the phase transition state of the pixel structure corresponding to different numbers of phase transition states, i.e., the phase that the pixel structure can modulate.

[0125] Step A2: Determine the phase transition state of the pixel structure corresponding to the current control phase, and determine the target number of phase transition states of the phase transition unit corresponding to the current control phase based on the correspondence.

[0126] In this embodiment of the invention, the current modulation phase refers to the phase that the pixel structure needs to be modulated at the current moment. The phase that the pixel structure needs to be modulated may be different at different times. Based on this current modulation phase, the phase transition state of the pixel structure closest to this modulation phase can be determined, and this phase transition state can be taken as the phase transition state of the pixel structure corresponding to the current modulation phase. For example, the phase transition states of the pixel structure include -2, -1, 0, 1, and 2 (the unit is rad); if the current modulation phase is 1.2, then the phase transition state of the pixel structure corresponding to 1 rad can be taken as the phase transition state of the pixel structure corresponding to the current modulation phase.

[0127] Furthermore, based on the correspondence between the phase transition states of the pixel structure and the number of phase transition states of the phase transition unit, the number of phase transition states of the phase transition unit corresponding to the current control phase can be determined. For ease of description, this embodiment refers to the number of phase transition states of the phase transition unit corresponding to the current control phase as the "target number of phase transition states", which can determine the number of crystalline phase transition units and / or the number of amorphous phase transition units required at present.

[0128] Step A3: Individually regulate the electrodes of at least some phase transition units to change the phase transition state of at least some phase transition units, and the number of phase transition states of the regulated phase transition units is consistent with the target number of phase transition states.

[0129] In this embodiment of the invention, each phase transition unit in the pixel structure includes individually controllable electrodes (first electrode 101 and second electrode 102). After determining the target number of phase transition states, the phase transition states of at least some phase transition units can be changed by individually controlling the phase transition unit electrodes, so that the number of phase transition states of the phase transition units after regulation is consistent with the target number of phase transition states, so that the regulated pixel structure can perform phase modulation according to the current regulation phase.

[0130] For example, this pixel structure includes four phase transition units, each capable of switching between crystalline and amorphous states. The pixel structure has five phase transition states: 0a4c, 1a3c, 2a2c, 3a1c, and 4a0c, with corresponding phases of -2, -1, 0, 1, and 2, respectively; where 'a' represents amorphous and 'c' represents crystalline. If the current phase transition state of the pixel structure is 1a3c (one amorphous phase transition unit and three crystalline phase transition units), it is used to achieve a modulation effect with a phase of -1. If the desired modulation phase is 1.3, meaning the current modulation phase is 1.3, then the phase transition state of the pixel structure needs to be adjusted to 3a1c, with a target number of three amorphous phase transition units and one crystalline phase transition unit. At this point, by controlling two of the original three crystalline phase transition units to change these two phase transition units from crystalline to amorphous, the phase transition state of the pixel structure can be adjusted to 3a1c, so that the number of phase transition states of the phase transition units after adjustment is the same as the target number of phase transition states.

[0131] The method for controlling pixel structure provided in this invention controls the electrodes of at least some phase transition units electronically, enabling quasi-continuous adjustable phase transition states of the entire pixel structure. Furthermore, the phase transition units can respond quickly to electronic excitation and rapidly switch between crystalline and amorphous states, thereby achieving rapid switching of the pixel structure's phase transition states. Moreover, the phase transition states of the pixel structure are only related to the number of phase transition states of the phase transition units. When the phase transition states of the phase transition units can be precisely controlled, the phase transition states of the pixel structure can also be precisely controlled, achieving high-speed and precise quasi-continuous phase modulation effects.

[0132] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A pixel structure, characterized by, The application relates to a pixel structure, which comprises: a plurality of phase change units (1) which are arranged in an array and are identical in structure; the phase change units (1) are used for regulating the phase of light propagation and are not sensitive to the polarization direction of light; the phase change unit (1) comprises an excitation element (10) and a phase change element (20); the excitation element (10) is used for applying independent excitation to the phase change element (20) so as to change the phase change state of the phase change element (20); the phase change element (20) comprises at least one nanostructure (201) made of a phase change material; the phase change state of the phase change element (20) comprises a crystal state and an amorphous state; the phase change state of the pixel structure is in one-to-one correspondence with the number of phase change states of the phase change units (1) in the pixel structure; the number of phase change states comprises the number of crystal phase change units and / or the number of amorphous phase change units; wherein the phase change state of the pixel structure is only related to the number of phase change units (1) with different phase change states contained in the pixel structure and is not related to the arrangement mode of the phase change units (1) with different phase change states.

2. The pixel structure of claim 1, wherein, The number of phase change units (1) is not more than 25.

3. The pixel structure of claim 1, wherein, The excitation element (10) of each phase change unit (1) comprises a first electrode (101) and a second electrode (102) which are arranged at intervals; the first electrode (101) and the second electrode (102) are electrically connected through the intermediate part of the phase change unit (1); an electric potential difference can be formed between the first electrode (101) and the second electrode (102); the temperature of the intermediate part between the first electrode (101) and the second electrode (102) is changed by using electro-thermal conversion so as to change the temperature of the phase change element (20).

4. The pixel structure of claim 3, wherein, The intermediate part comprises a first metal reflection layer (301); the phase change element (20) is located on the light reflection side of the first metal reflection layer (301); the first electrode (101) and the second electrode (102) are respectively electrically connected with the first metal reflection layer (301) and are located on the two sides of the phase change element (20).

5. The pixel structure of claim 4, wherein, The phase change unit (1) further comprises a first dielectric layer (401); the first dielectric layer (401) is located between the first metal reflection layer (301) and the phase change element (20) and abuts against the first metal reflection layer (301) and the phase change element (20).

6. The pixel structure of claim 4, wherein, The phase change unit (1) further comprises a first insulating layer (501); the first insulating layer (501) is located on one side of the first metal reflection layer (301); the phase change element (20), the first electrode (101) and the second electrode (102) are located on the side of the first metal reflection layer (301) which is away from the first insulating layer (501).

7. The pixel structure of claim 4, wherein, The phase change unit (1) further comprises a filler (60); the filler (60) is transparent in a working wave band; the filler (60) is filled between the nanostructures (201) of the phase change element (20).

8. The pixel structure of claim 3, wherein, The intermediate part comprises the phase change element (20); The first electrode (101) is electrically connected to one side of the phase change element (20), and the second electrode (102) is electrically connected to the other side of the phase change element (20).

9. The pixel structure of claim 8, wherein, The first electrode (101) is in a layer structure and is transparent in a working waveband. The phase change element (20) is located on one side of the first electrode (101), and the second electrode (102) is electrically connected to the side of the phase change element (20) away from the first electrode (101).

10. The pixel structure of claim 9, wherein, The excitation element (10) further comprises a connecting layer (103), and the connecting layer (103) is transparent in a working waveband. The connecting layer (103) is located on the side of the phase change element (20) away from the first electrode (101) and is electrically connected to the phase change element (20). The second electrode (102) is located between the first electrode (101) and the connecting layer (103) and is electrically connected to the connecting layer (103).

11. The pixel structure of claim 9, wherein, The first electrodes (101) of a plurality of the phase change units (1) are coplanar and are in an integrated structure.

12. The pixel structure of claim 9, wherein, The phase change unit (1) further comprises a second insulating layer (502). The second insulating layer (502) is located between the first electrode (101) and the second electrode (102) and abuts the first electrode (101) and the second electrode (102).

13. The pixel structure according to any one of claims 8-12, characterized in that, Further comprising: A substrate (70); the substrate (70) is transparent in a working waveband; A plurality of the phase change units (1) are located on at least one side of the substrate (70).

14. The pixel structure of claim 9, wherein, The phase change unit (1) further comprises a second metal reflection layer (302). The second metal reflection layer (302) is located on the side of the first electrode (101) away from the phase change element (20) or between the first electrode (101) and the phase change element (20). The side of the second metal reflection layer (302) close to the phase change element (20) is a light reflection side.

15. The pixel structure of claim 8, wherein, The first electrode (101) comprises a third metal reflection layer (303). The phase change element (20) is located on the light reflection side of the third metal reflection layer (303), and the second electrode (102) is electrically connected to the side of the phase change element (20) away from the third metal reflection layer (303).

16. The pixel structure of claim 15, wherein, The third metal reflection layers (303) of a plurality of the phase change units (1) are coplanar and are in an integrated structure.

17. The pixel structure of claim 15, wherein, The phase change unit (1) further comprises a third insulating layer (503). The third insulating layer (503) is located between the third metal reflection layer (303) and the second electrode (102) and abuts the third metal reflection layer (303) and the second electrode (102).

18. The pixel structure of claim 15, wherein, The phase change unit (1) further comprises a second dielectric layer (402) capable of conducting electricity. The second dielectric layer (402) is located between the third metal reflection layer (303) and the phase change element (20) and abuts the third metal reflection layer (303) and the phase change element (20).

19. The pixel structure of claim 3, wherein, One of the first electrode (101) and the second electrode (102) has a fixed potential.

20. The pixel structure of claim 19, wherein, The electrode with the fixed potential is grounded.

21. The pixel structure of claim 1, wherein, The nanostructure (201) is a polarization-unrelated structure.

22. The pixel structure of claim 21, wherein, The nanostructure (201) comprises at least one of a nano-cylinder structure, a hollow nano-pillar structure, a nano-hole structure, a nano-ring-hole structure, a nano-square-pillar structure, a nano-square-hole structure, a nano-square-ring structure, and a nano-square-ring-hole structure.

23. A metasurface, characterized in that, The pixel structure comprises a plurality of pixel structures as claimed in any one of claims 1-20, and the plurality of pixel structures are arranged in an array form.

24. A method of controlling a pixel structure as claimed in any one of claims 3-20, characterized in that The pixel structure comprises: a predetermined one-to-one correspondence between a number of phase change states of the phase change unit in the pixel structure and phase change states of the pixel structure; determining a phase change state of the pixel structure corresponding to a current control phase, and determining a target number of phase change states of the phase change unit corresponding to the current control phase according to the correspondence; individually controlling electrodes of at least part of the phase change units to change phase change states of the at least part of the phase change units, and the number of phase change states of the phase change units after the control is consistent with the target number of phase change states.

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