Superlens, optical element and light beam modulation method

Abstract

The invention provides a super lens, an optical element and a light beam modulation method, which can be applied to the field of super lenses. The super lens comprises a plurality of micro-units which are arranged at intervals in a first direction; wherein the plurality of micro-units comprise at least one first micro-unit, and the first micro-unit has a first rotating angle relative to the first direction, so that the extension direction of the first micro-unit is vertical to the polarization direction of the first light beam with the first high-order vector mode; the first micro unit is used for selectively allowing the first light beam to transmit under the irradiation of at least two light beams including the first light beam and reflecting other light beams in the at least two light beams; in the process of transmitting the first light beam, wavefront modulation is carried out on the first light beam based on the structure size of the first micro-unit, so that a first target light field is formed based on the modulated first light beam; wherein the at least two light beams have different high-order vector modes with respect to each other.

Description

Technical Field

[0001] This disclosure relates to the field of superlenses, and more specifically to a superlens, optical element, and beam modulation method. Background Technology

[0002] Vertical-cavity surface-emitting lasers (VCSELs) have become one of the most widely used light sources due to their low power consumption, relatively small divergence angle, and ability to be mass-produced on wafers. They can be applied in fields such as semiconductor lasers, laser printing, and lidar. Based on this, the selective output and modulation of beams with multiple high-order vector modes generated by the laser source have attracted widespread attention. Summary of the Invention

[0003] In view of the above problems, this disclosure provides a superlens, an optical element, and a beam modulation method.

[0004] According to one aspect of this disclosure, a superlens is provided, comprising a plurality of micro-units spaced apart in a first direction; wherein the plurality of micro-units includes at least one first micro-unit having a first rotation angle relative to the first direction such that the extension direction of the first micro-unit is perpendicular to the polarization direction of a first beam having a first higher-order vector mode; the first micro-unit is configured to: selectively allow the first beam to be transmitted and reflect other beams of the at least two beams including the first beam under illumination; and, during the transmission of the first beam, perform wavefront modulation of the first beam based on the structural dimensions of the first micro-unit to form a first target optical field based on the modulated first beam; wherein the at least two beams have different higher-order vector modes relative to each other.

[0005] According to another aspect of this disclosure, an optical element is provided, comprising: a substrate; the aforementioned superlens disposed on the substrate; and a vector beam emitter serving as a light source; wherein the vector beam emitter layer and the superlens are respectively disposed on opposite sides of the substrate, or respectively disposed on adjacent sides of the substrate, so that multiple beams emitted by the vector beam emitter layer pass through the substrate and are directed to the superlens; the multiple beams have different higher-order vector modes relative to each other; wherein the vector beam emitter comprises at least one of a photonic crystal structure, a whispering gallery structure, or a metasurface structure capable of emitting vector light.

[0006] According to another aspect of this disclosure, a beam modulation method implemented by the above-described superlens is provided, comprising: a first micro-unit selectively allowing the first beam to be transmitted and reflecting other beams among the at least two beams under illumination by at least two beams including the first beam; wherein the at least two beams have different higher-order vector modes relative to each other; and the first micro-unit performing wavefront modulation on the first beam based on the structural dimensions of the first micro-unit during the transmission of the first beam, so as to form a first target light field based on the modulated first beam.

[0007] According to embodiments of this disclosure, a superlens is provided. In this superlens, since the first micro-unit has a first angle relative to the first direction of the micro-unit arrangement, the extension direction of the first micro-unit can be perpendicular to the polarization direction of the first beam of the first higher-order vector mode. This allows selective transmission of the first beam and reflection of other higher-order vector modes when the first micro-unit is irradiated by beams of at least two higher-order vector modes. Thus, selective output of beams of different higher-order vector modes can be achieved. Simultaneously, during the transmission of the first beam, the first micro-unit can also perform wavefront modulation of the first beam based on its own structural dimensions. Based on this, the superlens of this disclosure improves the ability to perform on-chip manipulation of vector beams, thereby expanding the application scenarios of light sources capable of simultaneously emitting vector beams of multiple higher-order vector modes. Attached Figure Description

[0008] The above-mentioned contents, other objects, features and advantages of this disclosure will become clearer from the following description of embodiments of this disclosure with reference to the accompanying drawings, which will be described in conjunction with the drawings.

[0009] Figure 1 A schematic diagram of a superlens according to an embodiment of the present disclosure is shown.

[0010] Figure 2 A schematic diagram of a superlens according to another embodiment of the present disclosure is shown.

[0011] Figure 3 A schematic diagram of a superlens according to another embodiment of the present disclosure is shown.

[0012] Figure 4 A schematic diagram of a metasurface according to another embodiment of the present disclosure is shown.

[0013] Figure 5 A schematic diagram of an optical element according to an embodiment of the present disclosure is shown.

[0014] Figure 6 A schematic diagram illustrating the features of an optical element according to an embodiment of the present disclosure is shown.

[0015] Figure 7 A schematic diagram illustrating the structural features of a microcell according to an embodiment of the present disclosure is shown.

[0016] Figure 8 A schematic diagram illustrating the features of a superlens according to another embodiment of the present disclosure is shown.

[0017] Figure 9 A schematic diagram illustrating the features of a metasurface according to another embodiment of the present disclosure is shown.

[0018] Figure 10 The present invention illustrates the ability of a mode-selective focusing superlens provided according to embodiments of the present disclosure to select and focus multimode vector beams generated by Dirac vortex cavities with winding numbers w = 2 and w = 3.

[0019] Figure 11 A schematic diagram illustrating the transmission effect of a superlens according to an embodiment of the present disclosure is shown.

[0020] Figure 12 A schematic diagram illustrating the electric field characteristics of a superlens according to an embodiment of the present disclosure is shown.

[0021] Figure 13 A schematic diagram of a beam modulation method according to an embodiment of the present disclosure is shown. Detailed Implementation

[0022] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0024] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0025] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0026] To further improve laser emission capability and beam quality, two-dimensional photonic crystals have been introduced into lasers. In some schemes, the problem of large-area single-mode emission from two-dimensional surface-emitting lasers can be solved using Dirac-vortex topological cavities (hereinafter referred to as Dirac vortex cavities). Specifically, by combining Dirac vortices with generalized Kekulé modulation in a triangular lattice, the displacement or unit cell size of the structure in the photonic crystal can be changed, realizing the emission of large-mode area vector beams. Since the topological modes are located at the center of the band gap, they have the characteristics of a large free spectral range and stable single-mode emission. Based on this, by changing the number of windings in the cavity structure, Dirac vortex cavities can generate high-order multimode vector beams with arbitrary angular momentum and an arbitrary number of modes.

[0027] Furthermore, metasurfaces, as arrays composed of two-dimensional subwavelength artificially patterned micro- and nanostructures, exhibit powerful optical field manipulation capabilities, enabling efficient control of at least one of the physical dimensions of light, such as phase, amplitude, polarization, wavelength, or angular momentum, with subwavelength spatial resolution. Based on this, metasurfaces are widely used in many optical fields, promoting the development of micro- and nano-optical devices, such as holograms, imaging, and polarization detection. The on-chip integration of metasurfaces and photonic crystals has attracted widespread attention, triggering new breakthroughs in integrated optical devices. By designing metasurfaces, the functionality of on-chip light sources can be greatly expanded, integration density enhanced, and optical path complexity reduced in photonic device applications. This allows for the realization of functions such as monolithic holography, cavity mode control, or light source collimation. Therefore, the on-chip integration of these two technologies has a very broad application prospect.

[0028] In view of this, embodiments of the present disclosure provide a superlens and an on-chip integrated high-order vector beam mode selection and wavefront modulation method for beam modulation.

[0029] Figure 1 A schematic diagram of a superlens according to an embodiment of the present disclosure is shown.

[0030] like Figure 1As shown, the superlens of this embodiment may include a plurality of micro-units arranged at intervals along a first direction x. However, it should be understood that the embodiments of this disclosure are not limited thereto. In other embodiments of this disclosure, the plurality of micro-units are arranged in multiple columns along the first direction x and in multiple rows along a second direction y perpendicular to the first direction x, thereby forming a micro-unit array. The plurality of micro-units may be anisotropic relative to each other, but the embodiments of this disclosure are not limited thereto; the plurality of micro-units may also include isotropic micro-units. For example, the first direction x and the second direction y may be horizontal directions, but this disclosure does not limit this.

[0031] Furthermore, in this embodiment of the disclosure, the plurality of micro-units includes at least one first micro-unit. The material of the first micro-unit may include silicon or the like. Based on this, the first micro-unit can be irradiated using at least two light beams. These at least two light beams may be vector beams with different higher-order vector modes relative to each other. It should be further noted that a higher-order vector mode can refer to a mode that is distinct from the basic vector mode and has higher-order spatial distribution characteristics or multiple degrees of freedom coupling in the light vector field.

[0032] Furthermore, the first micro-unit has a first rotation angle relative to the first direction x. Specifically, the micro-unit has multiple extending axes in the plane formed by the first direction x and the second direction y, including the longest major axis, the extension direction of which is used as the extension direction of the micro-unit. Based on this, the first rotation angle of the first micro-unit relative to the first direction x can mean that the major axis of the first micro-unit has a first rotation angle relative to the first direction x, and the same applies below. Moreover, the arrangement direction of the micro-units (i.e., the first direction x) can be perpendicular to the polarization direction of the beam of the higher-order vector mode to be transmitted, but is not limited to this.

[0033] Because the first micro-unit has a first rotation angle relative to the first direction x, its extension direction is perpendicular to the polarization direction of the first beam having a first higher-order vector mode. Therefore, the first micro-unit can select from at least two beams, including the first beam, based on their higher-order vector modes, under illumination. Specifically, the first micro-unit allows the first beam to transmit and reflect other beams among the at least two beams. Furthermore, during the transmission of the first beam, the first micro-unit can perform wavefront modulation on the first beam based on its own structural dimensions, so as to form a first target light field based on the modulated first beam.

[0034] Based on this, in the superlens of this embodiment, since the first micro-unit has a first rotation angle relative to the first direction x of the micro-unit arrangement, the extension direction of the first micro-unit can be perpendicular to the polarization direction of the first beam of the first higher-order vector mode. This allows the first beam to be selectively transmitted when illuminated by beams of at least two higher-order vector modes, while reflecting the transmission of other higher-order vector modes. Thus, selective output of beams of different higher-order vector modes can be achieved. Simultaneously, during the transmission of the first beam, the first micro-unit can also perform wavefront modulation of the first beam based on its own structural dimensions. Based on this, the superlens of this embodiment improves the ability to manipulate vector beams on-chip, thereby expanding the application scenarios of light sources capable of simultaneously emitting vector beams of multiple higher-order vector modes (such as the aforementioned Dirac vortex cavity).

[0035] Figure 2 A schematic diagram of a superlens according to another embodiment of the present disclosure is shown.

[0036] like Figure 2 As shown, in the superlens of this embodiment, the plurality of micro-units further includes at least one second micro-unit. The at least one second micro-unit has a second rotation angle relative to the first direction x that is different from the first rotation angle, so that the at least one second micro-unit has a different transmission capability to the first beam than the first micro-unit.

[0037] For example, the second rotation angle can be perpendicular to the first rotation angle, such that the extension direction of the second micro-unit is parallel to the polarization direction of the first beam and perpendicular to the polarization direction of the second beam having a second higher-order vector mode among at least two beams. It should be understood that, in embodiments of this disclosure, the at least two beams may also have vector beams with other higher-order vector modes, which will not be elaborated upon here.

[0038] Thus, the second micro-unit can select from at least two beams, including the first beam and the second beam, based on the higher-order vector modes of the at least two beams. Specifically, the second micro-unit can allow the second beam to be transmitted and reflect other beams (such as the first beam described above) among the at least two beams, including the first beam and the second beam, under illumination. Furthermore, during the transmission of the second beam, the first micro-unit can perform wavefront modulation on the second beam based on the structural dimensions of the second micro-unit, so as to form a second target optical field based on the modulated first beam and the modulated second beam.

[0039] Based on this, in the embodiments of this disclosure, since the metasurface may include various micro-units tilted at different angles relative to the first direction x, the metasurface can selectively transmit and modulate corresponding high-order vector beams simultaneously with different types of micro-units. This facilitates the realization of specific optical fields.

[0040] Figure 3 A schematic diagram of a superlens according to another embodiment of the present disclosure is shown.

[0041] like Figure 3 As shown, the second micro-unit among the multiple micro-units has a different structural size from the first micro-unit, so that the first micro-unit and the second micro-unit each modulate the phase of the beam penetrating them to different degrees.

[0042] Specifically, the first micro-unit and the second micro-unit have different phase modulation capabilities relative to each other based on their respective structural dimensions, so that the first micro-unit and the second micro-unit can respectively modulate the first beam penetrating the first micro-unit and the second beam penetrating the second micro-unit to perform phase shifts of different degrees, so as to obtain the modulated first beam and the modulated second beam.

[0043] Based on this, in the embodiments of this disclosure, the superlens can selectively transmit higher-order vector beams while also modulating different higher-order vector beams with different wavefronts. Thus, it is possible to simultaneously modulate multiple higher-order vector beams with their wavefronts, facilitating the creation of specific optical fields.

[0044] Figure 4 A schematic diagram of a metasurface according to another embodiment of the present disclosure is shown. It should be understood that... Figure 4 This is just an example.

[0045] like Figure 4 As shown, in this embodiment, the metasurface may further include other micro-units besides the first and second micro-units. For example, the metasurface may further include other micro-units. For ease of description, these other micro-units may be referred to as third micro-units. Further, each of the third micro-units has a corresponding third rotation angle relative to the first direction x. The angle of the third rotation angle is greater than the first rotation angle and less than the second rotation angle. Further still, in embodiments of this disclosure, the third rotation angles of each of the third micro-units may be different relative to each other.

[0046] Furthermore, to achieve the formation of a specific light field, the third rotation angle of the third micro-units arranged along the first direction x can gradually vary sequentially along the first direction x. Similarly, the third rotation angle of the third micro-units arranged along the second direction y can gradually vary sequentially along the second direction y. For example, among multiple third micro-units arranged in at least one of the first or second directions x and y, the third rotation angle of the third micro-unit closer to the first micro-unit will be smaller than that of the third micro-unit farther from the first micro-unit. Moreover, the metasurface also includes multiple regions, each of which includes at least one first micro-unit, at least one second micro-unit, and at least one third micro-unit. These multiple regions can be mirror images of each other. For example, in these multiple regions, any region and another region adjacent to that region in the first direction x can be symmetrical about each other at the boundary between the two regions based on an axis parallel to the second direction y. Also, for example, any region and yet another region adjacent to that region in the second direction y can be symmetrical about each other at the boundary between the two regions based on an axis parallel to the first direction x. Specifically, in this embodiment, symmetry refers to the symmetrical rotation of the micro-units. For example, the rotation of the micro-units in any region is mirror-symmetrical with respect to the rotation of the micro-units in at least one of the other regions or yet another region.

[0047] Furthermore, the structural dimensions of the plurality of third micro-units may be the same as, different from, or the same as or different from each other; this disclosure does not limit this. Thus, embodiments of this disclosure can achieve wavefront modulation of multiple higher-order vector mode beams respectively, thereby realizing a specific optical field, while selectively transmitting beams of higher-order vector modes.

[0048] Figure 5 A schematic diagram of an optical element according to an embodiment of the present disclosure is shown.

[0049] like Figure 5 As shown, the optical element in this embodiment may include a substrate, a beam vector emitter, and the aforementioned superlens. The substrate material may include materials such as silicon dioxide. In this embodiment, the vector light emitter includes at least one of a photonic crystal structure, a whispering gallery structure, or a metasurface structure capable of emitting vector light, and is not limited thereto. Specifically, the vector light emitter may include the aforementioned Dirac vortex cavity. Thus, the vector beam emitter can be used as a light source. Specifically, the vector beam emitter can emit at least two beams. The at least two beams have different higher-order vector modes relative to each other.

[0050] Furthermore, in this embodiment, the superlens can be disposed on the substrate, specifically on one side surface of the substrate. In this embodiment, the vector beam emitter can also be disposed on the substrate. For example, the vector beam emitter and the superlens can be disposed on opposite sides of the substrate, or on adjacent sides of the substrate, so that at least two beams emitted by the vector beam emitter can pass through the substrate and reach the superlens. However, it should be understood that this embodiment is not limited thereto; in other embodiments, the vector beam emitter can be independent of the substrate.

[0051] Furthermore, in embodiments of this disclosure, the superlens may include stacked dielectric material layers and lens layers. The lens layer includes multiple micro-units and dielectric materials between the micro-units. The refractive indices of both the dielectric material layers and the dielectric materials are different from the refractive indices of the micro-units, so as to support and protect the micro-units while confining the light beam within the micro-units. For example, the dielectric material may include silicon dioxide. It should be noted that the stacked dielectric material layers and lens layers may be alternately stacked to form a multi-layered periodic structure, which is not limited in this respect.

[0052] The superlens of this disclosure will be further described below with reference to specific embodiments and data. It should be understood that this is merely an example.

[0053] Figure 6 A schematic diagram illustrating features of an optical element according to an embodiment of the present disclosure is shown. Specifically, Figure 6 (a) shows the Dirac cavity spectra with different winding numbers w according to embodiments of the present disclosure. Figure 6 (b) in the middle shows Figure 6 The Dirac cavity supercell structure with a winding number w=2, the phase distribution, and two degenerate orthogonal higher-order vector beams in (a) of the image. Figure 6 (c) in the middle shows Figure 6 In (b) of the image, the two modes are irradiated onto the metasurface on the front side through the quartz substrate. The upper figure shows the focal point of the transmission mode, and the blue arrows indicate the polarization distribution. Figure 6 (d) in the text shows Figure 6 In (c), the supersurface structure is arranged, θ is the structural rotation angle, and φ is the phase distribution. Figure 6 (e) in the middle shows Figure 6 The diagram in (c) shows the metasurface unit structure, where a is the lattice constant, h is the structure height, L is the length of the major axis, and W is the length of the minor axis.

[0054] Based on this, in the embodiments of this disclosure, the Dirac vortex cavity and metasurface are arranged as follows: Figure 6As shown in (c), the Dirac vortex cavity (e.g., with a thickness of 220 nm) and the metasurface (e.g., with a thickness of 1200 nm) are both located within a silicon material layer, with a silicon oxide layer as the intermediate substrate. Multiple high-order vector mode beams are generated by the Dirac vortex cavity, with an emission wavelength of 1550 nm. Figure 6 As shown in (b), a supercell structure of the Dirac vortex cavity contains six triangular structures, where the positions and phases of the triangles satisfy the equation:

[0055] (1)

[0056] Wherein, the maximum displacement of the triangle is m0 = 0.1s, s is the lattice constant corresponding to the photonic crystal cavity, r is the displacement of the triangular structure from the center of the Dirac cavity, R is the cavity well radius, and α = 4 is the shape factor. Thus, when the overall structure phase rotates once (w = 1), there is one topological mode within the bandgap; when the overall structure phase rotates once (w = 2), there are two degenerate modes between the bands. When considering manufacturing errors, the degeneracy of the two modes is broken. When w = 3, there are three modes between the bands, such as... Figure 6 The spectrum shown in (a) is as follows.

[0057] Furthermore, for the case where w = 2, the overall photonic crystal structure undergoes two phase rotations. In this case, the two vector beams N1 and N2 emitted from the Dirac vortex cavity illuminate the metasurface after passing through the substrate. These two vector beams N1 and N2 are spatially overlapping. To achieve two-mode selective output, the metasurface structure of this embodiment is as follows: Figure 6 As shown in (c) in the figure. Figure 6 (e) in the figure illustrates the structural features of the microunit, wherein the lattice constant a is fixed at 1000 nm and the height h is fixed at 1200 nm, but it should be understood that this disclosure does not limit it.

[0058] Furthermore, the micro-unit exhibits low transmittance for linearly polarized light with polarization directions parallel to the major axis, while having higher transmittance for light with polarization directions perpendicular to the major axis. Therefore, by obtaining the polarization distribution of the target vector beam to be transmitted and aligning the extension direction of the micro-unit perpendicular to the polarization direction (i.e., a structural rotation angle θ = σ + π / 2), transmission of the target vector beam can be achieved, while vector beams orthogonal to it are reflected (when θ = σ), i.e., N1 is reflected and N2 is transmitted. Here, σ represents the polarization direction. Moreover, by changing the major axis L and minor axis W of the micro-unit, different propagation phases can be generated without affecting the transmission capability. This allows the micro-unit to be placed at a position conforming to the phase profile φ (e.g., a phase profile that can focus the incident light), enabling wavefront manipulation of the transmitted light. Thus, in this embodiment, the rotation angle and structural features regarding the major axis L and minor axis W can be combined. Figure 6 As shown in (d), micro-units with rotation angle θ and phase profile φ can be arranged. The transmission situation is as follows. Figure 6 As shown in (c), the metasurface reflects the multimode high-order vector beam N1 emitted by the Dirac vortex cavity located on the other side of the substrate, and focuses the N2 mode while transmitting it, thus realizing the single-mode emission of the high-wound-number vector beam and the monolithic coupling of the vector beam wavefront modulation.

[0059] Figure 7 A schematic diagram illustrating the structural features of a microcell according to an embodiment of the present disclosure is provided. Specifically, Figure 7 (a) shows the transmittance of the unit structure provided according to an embodiment of the present disclosure when the incident light polarization is perpendicular to the long axis. Figure 7 (b) shows the transmittance of the unit structure provided according to an embodiment of the present disclosure when the incident light polarization is parallel to the long axis. Figure 7 (c) shows the propagation phase of the unit structure when the incident light polarization is perpendicular to the major axis, according to an embodiment of the present disclosure. Figure 7 Figure (d) shows the structural parameters provided according to embodiments of this disclosure. Left: Dimensions and phases of the three selected structures (marked in pink), with numbers in parentheses representing (major axis length, minor axis length, phase), respectively; Middle: Transmittance of the structure at different rotation angles, with the solid line representing the transmittance when the incident light polarization state is parallel to the major axis (shown in the left inset), and the dashed line representing the transmittance when the incident light polarization state is perpendicular to the major axis (shown in the right inset); Right: Influence of the incident light polarization direction on transmittance when the structure is placed at a fixed angle (red line P1, blue line P2, green line P3). Figure 7In this context, Transmittance represents transmittance; Transmittance of perpendicular to the long axis represents transmittance perpendicular to the long axis; Transmittance of parallel to the long axis represents transmittance parallel to the long axis; and Phase of perpendicular to the long axis represents phase perpendicular to the long axis.

[0060] Based on this, the following embodiments of this disclosure describe the research process for rectangular unit cell structures of different sizes. To obtain a suitable structure constituting the metasurface, the unit cell structure can be simulated using COMSOL Multiphysics. In this embodiment, the major axis L of the rectangular micro-units scans from 500 nm to 800 nm, and the W of the rectangular micro-units ranges from 100 nm to 500 nm. Figure 7 In the diagram, (a), (b), and (c) represent the transmittance when the incident light is polarized perpendicular to the long axis, the transmittance when the incident light is polarized parallel to the long axis, and the propagation phase when the incident light is polarized perpendicular to the long axis, respectively. To meet the requirements of the superlens, micro-units with high transmittance when the incident light's polarization direction is perpendicular to the long axis, low transmittance when the incident light is parallel to the long axis, and a transmission phase covering 0-2π are selected. Based on this, the embodiments of this disclosure select three micro-unit structures P1, P2, and P3. Figure 7 The left side of (d) in the diagram shows the parameters of the structure. These three micro-unit structures are sufficient to meet the phase requirements from 0 to 2π. Figure 7 Figure (d) shows the transmittance of three micro-unit structures at different rotation angles θ, where the solid line represents the case where polarization is parallel to the major axis (θ = σ), and the dashed line represents the case where polarization is perpendicular to the major axis (θ = σ + π / 2). It can be seen that all three micro-unit structures maintain high transmittance (greater than 0.94) across the entire angle for incident light with polarization perpendicular to the major axis (shown in the right-hand inset, the yellow arrow represents the polarization direction of the incident light). However, for incident light with polarization parallel to the major axis (shown in the left-hand inset), they exhibit lower transmittance across the entire angle, with a maximum value less than 0.24. The right figure shows the effect of the angle between the major axis of the micro-unit structure and the polarization direction of the incident light on the transmittance. As shown in the inset, the major axes of the micro-unit structures are all placed parallel to the x-axis to change the polarization direction σ of the incident light that the micro-unit structure allows to transmit. From the micro-unit structures, P3, with relatively high transmittance, still only has a transmittance of 0.25 at a deviation of 37°. This indicates that the discontinuously distributed micro-unit structure has the ability to select vector beams with continuous polarization distribution. Furthermore, in the embodiments of this disclosure, the superlens may include the three micro-unit structures described above.

[0061] Furthermore, in this embodiment, if the individual micro-units constituting the superlens only satisfy the condition that their rotation angles are perpendicular to the polarization direction of the higher-order vector beam mode to be transmitted, but the micro-unit sizes remain consistent, then the superlens only selects the beam of the higher-order vector mode, without modulating the beam into a specific optical field through wavefront modulation. The following is a detailed description in conjunction with the accompanying drawings.

[0062] Figure 8 A schematic diagram illustrating the features of a superlens according to another embodiment of the present disclosure is shown. Specifically, Figure 8 (a) in the middle shows Figure 6 In (b) of the two modes of beams N1 and N2, the mode selection of transmission N1 is shown by the superlens and arrangement method. The upper part shows the rotation angle and phase distribution, and the lower part shows the actual arrangement of the structure. Figure 8 (b) in the middle shows Figure 8 In (a) of the superlens structure, when N1 is incident, the full field distribution and polarization distribution of the transmitted light field are shown. The white arrows indicate the polarization states. Figure 8 (c) in the middle shows Figure 8 In (a) of the superlens structure, when N2 is incident, the full field distribution and polarization distribution of the transmitted light field are shown. The white arrows indicate the polarization states. Figure 8 (d) in the text shows Figure 6 In (b) of the two beam modes N1 and N2, the mode selection superlens and arrangement method of the transmission N2 mode are shown above, with the rotation angle and phase distribution above, and the actual arrangement of the structure below. Figure 8 (e) in the middle shows Figure 8 In (d) of the superlens structure, the full-field distribution and polarization distribution of the transmitted light field when N1 is incident are shown. The white arrows indicate the polarization states. Figure 8 (f) in the middle shows Figure 8 In (d) of the superlens structure, the full-field distribution and polarization distribution of the transmitted light field when N2 is incident are shown. The white arrows indicate the polarization states. Figure 8 (g) in the text shows Figure 8 (a) and Figure 8 In the superlens in (d), the transmission efficiency for different modes is shown, with red representing N1 transmittance and blue representing N2 transmittance. Intensity rate represents the light intensity ratio.

[0063] Based on this, in this embodiment, a superlens with only multimode vector beam mode selection is studied. For example, the finite-difference time-domain (FDTD) method can be used to simulate the superlens to save computational resources. In this embodiment, the incident light is still two mutually orthogonal vector beams with angular momentum of 2, namely N1 and N2, generated by a Dirac vortex cavity with a winding number of 2, as shown below. Figure 6 As shown in (b) of the diagram. Figure 8(a) and (d) in the diagram are two orthogonal modes (polarization states in space are perpendicular to each other) selected superlenses. The structure rotation angle and phase gradient are shown above. Only a 16×16 array is shown here. The actual model can be 40×40. It should be understood that the embodiments disclosed herein are not limited to this.

[0064] Furthermore, in the design, Figure 8 (a) Transmission of N1 by the superlens, Figure 8 In (b) of the diagram, the transmission mode N2 of the superlens is shown. From the structural rotation distribution and structural arrangement diagram, it can be seen that the micro-units in the two types of superlenses are arranged perpendicularly to each other. Since only the mode selection function is demonstrated here, the phase gradient distribution is 0. All structures are built based on the aforementioned micro-unit structure P3. However, it should be understood that other micro-unit structural components such as metasurface arrays can also be used, which will not be elaborated here. Let the beams of the two higher-order vector modes be incident on the two superlenses respectively. Figure 8 In (b), N1 is incident to Figure 8 The transmitted light field distribution of the superlens shown in (a) has a global shape almost identical to that of the incident light, and the shapes of the two orthogonal components are also consistent with the vector distribution of the incident light. Its topological number remains 2, preserving the original light field's mode morphology relatively well. However, for the N2 mode incident case, almost no light field mode is transmitted; most of the energy is reflected, and only a small amount of leaked light field is received by the detector. And for... Figure 8 The case of the superlens shown in (d) is the opposite, with the N2 mode being fully transmitted, while the N1 mode is almost completely transmitted. Figure 8 (g) in the figure shows the transmission intensity ratio. The two superlenses account for 91.7% of the transmission intensity for the transmission vector beam mode, while it is only 8.3% for the non-transmission vector beam mode. It can be seen that the mode selection superlens of the present disclosure embodiment has high working efficiency.

[0065] In this embodiment, if the discrete micro-units constituting the superlens only meet the phase distribution requirement in terms of structural dimensions, but the rotation angles of the micro-units remain consistent, then the superlens can only transmit linearly polarized light perpendicular to the structural rotation angles and modulate its wavefront, without needing to select higher-order vector beam modes. The following detailed description is in conjunction with the accompanying drawings.

[0066] Figure 9 A schematic diagram illustrating the features of a metasurface according to another embodiment of the present disclosure is shown. Specifically, Figure 9 (a) shows a schematic diagram and arrangement method of a focusing superlens that can transmit X-ray polarized light according to an embodiment of the present disclosure. Figure 9 (b) in the middle shows Figure 9 In (a) of the superlens structure, when X-ray polarized light is incident, the electric field distribution of the light field at the focal point is shown. Figure 9 (c) in the middle shows Figure 9 In (a) of the superlens structure, when Y-polarized light is incident, the electric field distribution of the light field at the focal point is shown. Figure 9 (d) shows a schematic diagram and arrangement method of a focusing superlens that can transmit Y-polarized light according to an embodiment of the present disclosure. Figure 9 (e) in the middle shows Figure 9 In the superlens structure in (d), when X-ray polarized light is incident, the electric field distribution of the light field at the focal point is shown. Figure 9 (f) in the middle shows Figure 9 In the superlens structure in (d), when Y-polarized light is incident, the electric field distribution of the light field at the focal point is shown. Figure 9 (g) in the text shows Figure 9 (a) and Figure 9 The superlens in (d) shows the transmission efficiency of X-polarized and Y-polarized light. Red represents the transmittance of X-polarized light, and blue represents the transmittance of Y-polarized light.

[0067] Based on this, Figure 7 The present invention also implements a polarization-selective focusing superlens by selecting three micro-unit structures with phase coverage from 0 to 2π. In this embodiment, since the superlens selects only linearly polarized light, the structure rotation angles are set to π / 2 and 0, respectively transmitting X-ray polarized light (XLP) and Y-ray polarized light (YLP). To achieve the focusing effect, the phase profile φ(r) of the superlens can be calculated using the following formula:

[0068] (2)

[0069] Where the incident light wavelength λ = 1550 nm, the superlens focal length f = 10 μm, and l is the distance from the unit structure to the center of the superlens. From this, the phase profile φ(r) of the focusing superlens can be obtained, allowing the micro-units closest to the phase requirement to be arranged at the corresponding positions in the superlens array to achieve the focusing effect. XLP and YLP planar light can be incident on the superlens respectively. Figure 9 The superlens array shown in (a) can transmit XLPs but not YLPs. It should be noted that the actual simulated superlens can still be 40×40 in size. Figure 9 In Figure (b), the transmitted light field is shown when the XLP is incident, with the detector placed 10 μm above the superlens. To better illustrate the spot morphology, only the electric field distribution within a 20 μm × 20 μm area is shown here. The field distribution shows that the electric field forms a focused spot at the center. Figure 9 In the diagram, (c) represents a detector 10 μm away from the superlens at the time of YLP incident illumination, which does not form a focal point or any speckle pattern. Similarly, Figure 9In the diagram, (d) represents the superlens array of the transmissive YLP. When the XLP is incident, as... Figure 9 In (e), the detector did not receive an electric field signal. Figure 9 (f) indicates that, upon YLP incidence, the focal point is generated at the center of the array at a distance of 10 μm. Numerical aperture NA = 0.89. Figure 9 In the figure, (g) represents the transmittance of linearly polarized light. The superlens array transmits 91.6% of the intensity of polarized light that is allowed to pass through, while only 8.4% transmits the intensity of polarized light that is not allowed to pass through. The above results show that the superlens can perform wavefront modulation of transmitted light while realizing the function of a polarizer.

[0070] Figure 10 This illustration demonstrates the ability of a mode-selecting focusing superlens, according to embodiments of the present disclosure, to select and focus multimode vector beams generated by Dirac vortex cavities with winding numbers w = 2 and w = 3. The left four columns represent w = 2, and the right nine columns represent w = 3. The upper section shows the wavefront morphology of the vector beam mode and the superlens structure arrangement, with blue arrows representing polarization directions. The middle section shows the intensity distribution of the mode after passing through the corresponding superlens, with the four rows representing the total field, X-polarization component, Y-polarization component, and Z-polarization component, respectively. The lower section shows the transmission intensity ratio. Here, Transmission intensity rate represents the transmitted light intensity ratio; Focus intensity represents the focused intensity; Vector light patterns and structural arrangement represents the vector light field pattern and structural arrangement; and Metalens serial number M represents the superlens serial number M.

[0071] Based on this, the beam selection and focusing functions for various high-order vector modes can be coupled, and the structural arrangement method is as follows: Figure 6 As shown. Figure 10 The efficiency of the mode-selective focusing superlens for Dirac vortex cavities with winding numbers w = 2 and w = 3 was also demonstrated. x This represents the ability to transmit and modulate N. x A pattern of superlens arrays. With Figure 9Similarly, the focal length can be set to 10 μm. When beams N1 and N2 of two higher-order vector modes with a winding number w = 2 pass through superlens M1, most of the N2 vector beam is reflected, while the N1 vector beam is transmitted, and both can be well focused at the focal length. Only the electric field distribution within a 10 μm × 10 μm area is shown here. The polarization intensity at the focal point indicates that its X and Y polarization components are consistent with the incident mode. Simultaneously, at the focal point, the focused spot also has two strong points in the Z component, due to the in-plane deflection of the wavefront in this polarization direction, generating a polarization component in the Z direction. As can be seen from the transmission intensity ratio below, compared to the two superlenses mentioned above, the mode-selective focusing superlens has a transmission mode intensity ratio of 73.4% and a non-transmission mode intensity ratio of 26.6%, resulting in a slight decrease in efficiency, but it can still produce approximately three times the intensity, demonstrating a certain degree of selectivity. When the N1 and N2 vector beams pass through superlens M2, most of the N1 vector beam is reflected, while the N2 vector beam is transmitted. The Z-component of the N2 vector beam is orthogonal to the Z-component of the N1 vector beam, conforming to the polarization distribution characteristics of the two vector beams. In this case, the intensity of the non-transmittent mode of the superlens accounts for only 27.1%.

[0072] Furthermore, this disclosure also relates to the selectivity of a mode-selective focusing superlens for vector beams of three higher-order vector modes generated by a Dirac vortex cavity with w = 3. The angular momentum of the beams N3, N4, and N5 in the three modes are 3, 3, and 4, respectively, and the polarization directions of N3 and N4 are orthogonal to each other. To match the mode angular momentum, the number of rotations of the superlenses M3, M4, and M5 are correspondingly changed to 3, 3, and 4. The transmission intensity ratios of the superlenses M3 and M4 for beams N3 and N4 are 53.4% ​​and 54.5%, respectively, while the transmission intensity ratios for their orthogonal states are 18.2% and 15.9%, respectively, showing a difference of approximately three times. However, the selectivity of the superlenses M3 and M4 for N5 is relatively poor because the angular momentum of beam N5 differs from the number of rotations of the superlenses M3 and M4, and the long axis of the structure is not completely parallel to the mode polarization direction, resulting in more leakage for mode N5. Furthermore, the superlens M5 exhibits poor selectivity for beam modes N3 and N4, with little difference in transmission intensity among the three modes. Simulation results show that the embodiments of this disclosure demonstrate higher selectivity for two completely orthogonal modes with the same angular momentum.

[0073] Figure 11 A schematic diagram illustrating the transmission effect of a superlens according to an embodiment of the present disclosure is provided. Specifically, Figure 11 Figure (a) shows the electric field distribution of the transmission mode of a mode-selective focusing superlens with a focal length of 5 micrometers provided according to an embodiment of the present disclosure. The upper figure is the xz plane, the lower figure is the xy plane at the white dashed line, and the white solid line is the relative intensity. Figure 11(b) shows the electric field distribution of the transmission mode of a mode-selective focusing superlens with a focal length of 10 micrometers provided according to an embodiment of the present disclosure. Figure 11 (c) shows the electric field distribution of the transmission mode of a mode-selective focusing superlens with a focal length of 15 micrometers provided according to an embodiment of the present disclosure. Figure 11 (d) in the figure shows the electric field distribution of the transmission mode of a mode-selective focusing superlens with a focal length of 20 micrometers provided according to an embodiment of the present disclosure. Figure 11 (e) in the middle shows Figure 11 The superlens effect in (a) to (d) shows the ratio of vector spot radius before and after transmission in red, and the intensity ratio in non-transmission mode in blue.

[0074] Furthermore, embodiments of this disclosure also investigate mode-selective focusing superlenses with different focal lengths. Figure 11 The focal lengths (a) to (d) are designed to be 5 μm, 10 μm, 15 μm and 20 μm, respectively. Figure 11 The figure shows the electric field distribution of four superlenses in the xz plane, with the white dashed lines indicating the locations of the strongest electric fields. Because the phase of a superlens is discontinuous and the phase of a single superlens unit cannot perfectly match the theoretical phase distribution, the locations of the strongest electric fields deviate from the focal length. The actual locations of the white dashed lines are 6.5 μm, 11.5 μm, 17 μm, and 22 μm, respectively. Figure 11 The solid white lines in the figure represent the relative intensity at the locations of the dashed white lines. It can be seen that the superlens with a focal length of 10 μm has the highest relative intensity, while the superlens with a focal length of 5 μm has a lower intensity. This is because the superlens with a focal length of 5 μm has a larger numerical aperture, resulting in greater diffraction intensity and dispersing the intensity of the main light spot. The figure below shows the light spot morphology in the xy-plane at the location of the dashed white lines. Figure 6 In diagram (e), the red dotted line represents the ratio of the radius of the vector light spot at the focal length to that of the incident vector light spot as the focal length changes. The result is similar to the focusing law of plane light; the radius of the focused vector light spot increases with increasing focal length. Furthermore, as the focal length increases, the z-polarization component of the transmitted light wavefront decreases, and the shape of the vector light spot focal point gradually becomes more uniform. The blue dotted line represents the intensity ratio of the non-transmittent mode, which does not change significantly with increasing focal length, demonstrating strong operational stability.

[0075] Figure 12 A schematic diagram illustrating the electric field characteristics of a superlens according to an embodiment of the present disclosure is shown. Specifically, Figure 12 (a) shows the electric field distribution in the yz plane of a mode-selective superlens with a focal length of 1 μm provided according to an embodiment of the present disclosure, with the topological charge of the incident vector beam being 4. Figure 12 (b) in the middle shows Figure 12The electric field distribution of the three components in the xy plane at the position of the white dashed line in (a) is distributed from top to bottom as X, Y and Z components. Figure 12 (c) in the middle shows Figure 12 In (b), the electric field strength of the three components in the xy plane at the white dashed line position is distributed from top to bottom as X, Y, and Z components, and the blue dashed line is the full width at half maximum (FWHM). Normalized intensity represents the normalized intensity.

[0076] To further explore the characteristics of the focused spot, this disclosure further studies the focused spot of the high-order mode selective output mode, specifically a mode with a topological kernel of 4 in the third-order topological cavity mode, with a focal length of 5 μm. However, it should be understood that this disclosure is not limited to this. Figure 12 As shown in (a), the numerical aperture of the superlens is approximately 1, and the three component fields of the field x, y, and z are distributed as follows: Figure 12 As shown in (b), where the light intensity I x and I y The light spot deforms compared to before focusing, mainly due to the wavefront modulation of the outgoing light spot by the superlens. This also leads to the change in light intensity I after focusing. z The reason for having two fewer light spots than in the x and y directions is that, in addition, the linear morphology of the light spots at the dashed lines of their respective field distributions is as follows: Figure 12 As shown in (c), the minimum focusing size is approximately 0.31λ. Based on this, the superlens of the present disclosure can achieve high transmittance and small focused spot output, which has promising applications in optical processing and optical power.

[0077] Based on this, this disclosure proposes a method for selecting and modulating multimode high-order vector beams generated by a Dirac vortex cavity on a single chip. This method utilizes the difference in transmittance of linearly polarized light along the major and minor axes of a rectangular structure, and reflects vector beam modes whose polarization distribution aligns with the major axis of the rectangular structure, while transmitting vector beams orthogonal to it. For example, three structures covering phases from 0 to 2π can be selected from a database, enabling wavefront phase modulation of the transmitted vector beam. In this disclosure, a superlens with only mode selection functionality is simulated, showing a transmitted mode intensity ratio of 91.7% and a non-transmitted mode ratio of only 8.3%. Furthermore, the shape of the transmitted vector beam spot remains undistorted. Then, a focusing superlens with polarizer capabilities is realized using three rectangular structures with different phases, focusing XLP (YLP) at the focal point and reflecting linearly polarized light orthogonal to it, with non-transmitted polarized light accounting for only 8.4%. Finally, by functionally coupling the "rotation angle" and "structural dimensions," while ensuring the structural long axis is horizontal with the non-transmissive polarization direction, the three micro-unit structures described above satisfy the phase profile, thus realizing a focusing superlens with mode selection capabilities. The intensity of the transmitted mode on the focal plane is three times that of the orthogonal non-transmissive mode, and the focal point does not undergo significant distortion, demonstrating good focusing ability. Furthermore, its working efficiency remains almost consistent across different focal lengths, exhibiting good stability. This superlens enables on-chip selection and modulation of high-order vector beams from a Dirac vortex cavity, allowing it to emit single-mode high-order vector beams as an independent fiber source. Its wavefront manipulation capabilities enable it to achieve monolithic vector beam holography. This improves on-chip manipulation capabilities of vector beams and expands the application scenarios of Dirac vortex cavities.

[0078] Figure 13 A schematic diagram of a beam modulation method according to an embodiment of the present disclosure is shown.

[0079] like Figure 13 As shown, the beam modulation method of this embodiment includes operations S1310 to S1320.

[0080] In operation S1310, the first micro-unit, under illumination by at least two beams including the first beam, selectively: allows the first beam to transmit and reflects other beams among the at least two beams.

[0081] During operation S1320, the first micro-unit modulates the first beam based on the structural dimensions of the first micro-unit during the transmission of the first beam, so as to form a first target light field based on the modulated first beam.

[0082] For example, wavefront modulation of a first beam based on the structural dimensions of a first micro-unit to form a first target optical field includes: the first micro-unit controlling the phase shift of the first beam to obtain the modulated first beam. The beam modulation method further includes: a second micro-unit selectively allowing the transmission of a second beam and reflecting the first beam when irradiated by at least two beams. During the transmission of the second beam, the second micro-unit controls the phase shift of the second beam based on its structural dimensions to obtain the modulated second beam, so that a second target optical field is formed based on the modulated first beam and the modulated second beam. However, it should be understood that the beam modulation method of this disclosure is not limited to this; specific examples can be found in the various beam modulation methods based on superlenses described above, which will not be elaborated upon here.

[0083] In this embodiment, the modulation method allows the superlens and photonic crystal cavity to be distributed on both sides of a transparent substrate. The superlens comprises an array of multiple micro-units. The superlens satisfies all or one of the following conditions: when the vector beam emitter generates two or more higher-order vector beams, the superlens can transmit a higher-order vector beam with a specific topological kernel number and reflect a higher-order vector beam orthogonal to it by applying different rotation angles to the unit structures at different positions; without applying rotation angles to the superlens array, using structures of different sizes to form a metasurface can polarize the incident polarized light and modulate its wavefront; under the premise of the above functions, the wavefront of the transmitted higher-order vector beam can be modulated to achieve focusing and other functions.

[0084] Those skilled in the art will understand that the features described in the various embodiments of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0085] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A superlens comprising a plurality of micro-units spaced apart in a first direction; in, The plurality of micro-units includes at least one first micro-unit, the first micro-unit having a first rotation angle relative to the first direction, such that the extension direction of the first micro-unit is perpendicular to the polarization direction of the first beam having a first higher-order vector mode. The first micro-unit is used for: Under illumination by at least two beams, including the first beam, selective transmission of the first beam is permitted, and reflection of other beams among the at least two beams is achieved; and During the transmission of the first beam, the first beam is wavefront modulated based on the structural dimensions of the first micro-unit so as to form a first target light field based on the modulated first beam; wherein the at least two beams have different higher-order vector modes relative to each other.

2. The superlens according to claim 1, characterized in that, The plurality of micro-units further includes at least one second micro-unit, the at least one second micro-unit having a second rotation angle relative to the first direction that is different from the first rotation angle, such that the at least one second micro-unit has a different transmission capability to the first beam than the first micro-unit.

3. The superlens according to claim 2, characterized in that, The second rotation angle is perpendicular to the first rotation angle, such that the extension direction of the second micro-unit is parallel to the polarization direction of the first beam and perpendicular to the polarization direction of the second beam having a second higher-order vector mode among the at least two beams; The second micro-unit is used for: Under the illumination of the at least two light beams, the second light beam is selectively allowed to transmit, and the first light beam is reflected; and During the transmission of the second beam, the second beam is wavefront modulated based on the structural dimensions of the second micro-unit so as to form a second target light field based on the modulated first beam and the modulated second beam.

4. The superlens according to any one of claims 1 to 3, characterized in that, The second micro-unit among the plurality of micro-units has a different structural size from the first micro-unit, such that the first micro-unit and the second micro-unit each modulate the phase of the beam penetrating them to different degrees.

5. The superlens according to claim 4, characterized in that, The first micro-unit and the second micro-unit have different phase modulation capabilities relative to each other based on their respective structural dimensions, so that the first micro-unit and the second micro-unit can respectively modulate the first beam penetrating the first micro-unit and the second beam penetrating the second micro-unit to perform phase shifts of different degrees, so as to obtain the modulated first beam and the modulated second beam.

6. An optical element, comprising: Substrate; A superlens as described in any one of claims 1 to 5 disposed on the substrate; as well as A vector beam emitter used as a light source; wherein the vector beam emitter and the superlens are respectively disposed on opposite sides of the substrate, or respectively disposed on adjacent sides of the substrate, so that at least two beams emitted by the vector beam emitter pass through the substrate and are directed toward the superlens; the at least two beams have different higher-order vector modes relative to each other; The vector light emitter includes at least one of a photonic crystal structure, a whispering gallery structure, or a metasurface structure capable of emitting vector light.

7. The optical element according to claim 6, characterized in that, The plurality of micro-units are arranged in multiple columns along the first direction and in multiple rows along a second direction perpendicular to the first direction; The micro-unit has multiple extending axes in a plane formed based on the first direction and the second direction, the multiple extending axes including the longest long axis, the extension direction of the long axis being used as the extension direction of the micro-unit.

8. The optical element according to claim 6 or 7, characterized in that, The superlens includes stacked dielectric material layers and lens layers; the lens layer includes the plurality of micro-units and the dielectric material between the plurality of micro-units; The refractive index of the dielectric material layer and the dielectric material is different from that of the micro-unit.

9. A beam modulation method implemented by a superlens as described in any one of claims 1 to 5, comprising: The first micro-unit, when illuminated by at least two beams including the first beam, selectively allows the first beam to be transmitted and reflects other beams among the at least two beams; wherein the at least two beams have different higher-order vector modes relative to each other; During the transmission of the first beam by the first micro-unit, the first beam is wavefront modulated based on the structural dimensions of the first micro-unit, so as to form a first target light field based on the modulated first beam.

10. The beam modulation method according to claim 9, characterized in that, The plurality of micro-units further includes at least one second micro-unit, the at least one second micro-unit having a second rotation angle relative to the first direction; the second rotation angle is perpendicular to the first rotation angle, such that the extension direction of the second micro-unit is parallel to the polarization direction of the first beam and perpendicular to the polarization direction of the second beam having a second higher-order vector mode among the plurality of beams; The step of performing wavefront modulation on the first beam based on the structural size of the first micro-unit in order to form a first target light field based on the modulated first beam includes: the first micro-unit modulating the first beam to perform phase shifting to obtain the modulated first beam. The beam modulation method further includes: when the second micro-unit is irradiated by the at least two beams, the second micro-unit selectively allows the second beam to be transmitted and reflects the first beam; during the transmission of the second beam, the second micro-unit adjusts the phase shift of the second beam based on the structural size of the second micro-unit to obtain a modulated second beam, so as to form a second target light field based on the modulated first beam and the modulated second beam.

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