Left-handed and right-handed light wave beam chiral deflection device based on plasma metasurface

Abstract

The utility model discloses a left-handed and right-handed light wave beam chiral deflection device based on a plasma metasurface, and relates to a nanometer optical technology. Comprising a metasurface which is formed by periodically arranging a plurality of super-cells, each super-cell is composed of eight super-atoms, the latter super-atom in each super-cell rotates by 11.25 degrees anticlockwise compared with the former super-atom, and the size of the latter super-atom in each super-cell is changed compared with the size of the former super-atom. The metasurface device can work in an optical wave band and has a chiral function of left-handed and right-handed optical decoupling. The chiral function is realized by utilizing the cooperative regulation and control of the superatoms on the transmission phase and the geometric phase, so that the metasurface does not form the phase gradient for right-handed rotation light and forms the phase gradient for left-handed rotation light in the horizontal direction. When right-handed light enters the metasurface, normal specular reflection of a reflection wave beam occurs according to a conventional Snell law; and when the left-rotation light enters, the reflected wave beam is subjected to abnormal non-specular reflection at a certain angle according to the generalized Snell law.

Description

Technical Field

[0001] The utility model relates to the technical field of nano-optics, in particular to a left-handed and right-handed optical wave beam chiral deflection device based on a plasma super surface. Background Art

[0002] How to control light on demand has always been a hot topic in the field of photonics technology. Among them, preparing metasurfaces to achieve arbitrary deflection of light has become an effective way. Left-handed and right-handed optical beam chiral deflection devices are usually used to control the polarization direction of optical beams to achieve optical signal processing, transmission and modulation. These devices have important application prospects in optical communications, optical sensing, optical computing and other fields.

[0003] Designing left-handed and right-handed optical beam chiral deflection devices usually requires comprehensive consideration of material selection, device structure design, and optical property optimization. Existing solutions are mainly designed through ideas such as chiral optical material selection, simulation and optimization design, nanostructure design, and optoelectronics integration.

[0004] The nanostructure design scheme is mainly realized by constructing a metasurface. Among them, the regulation of different circularly polarized electromagnetic waves by the metasurface with a simple geometric phase is often mirrored, which hinders some practical applications that require the separate control of polarized light. Therefore, it is very important to achieve independent control of two circularly polarized electromagnetic waves with different rotation directions for practical applications.

[0005] In view of this, a metasurface combining geometric phase and transmission phase is proposed. How to provide a spin-decoupled left-handed and right-handed optical beam chiral deflection device that can work in the visible light band is a technical problem that needs to be solved in this field. Summary of the invention

[0006] The purpose of the utility model is to provide a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface, which can work in the visible light band. The utility model can selectively deflect left-handed and right-handed light through the metasurface structure, and control the phase of light by using the specific arrangement and size change of meta-atoms, thereby affecting the propagation direction of the light beam.

[0007] In order to achieve the above purpose, the utility model is implemented in the following ways:

[0008] The utility model provides a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface, comprising:

[0009] A metasurface, wherein the metasurface is formed by a plurality of supercells arranged in a periodic manner, wherein each supercell contains 8 superatoms, and in each supercell, the superatoms are arranged according to a specific rule and rotated by a certain angle, and the size of the superatoms also changes regularly; specifically, the next superatom in each supercell rotates 11.25° counterclockwise compared to the previous superatom, and the size of the next superatom in each supercell changes compared to the previous superatom; for left-handed light incidence, the next superatom in each supercell produces a geometric phase difference of -22.5° relative to the previous superatom, and the last superatom in each supercell has a geometric phase difference of -22.5° relative to the first superatom. The atoms produce a -180° geometric phase difference, which, combined with the -180° transmission phase difference caused by the size change of the superatoms in each supercell, causes the metasurface to form a phase gradient in the horizontal direction for left-handed light, thereby presenting an abnormal deflection. For right-handed light incidence, the latter superatom in each supercell produces a +22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a +180° geometric phase difference with respect to the first superatom, which, combined with the -180° transmission phase difference caused by the size change of the superatoms in each supercell, causes the metasurface to have no phase gradient for right-handed light, thereby presenting a mirror deflection effect.

[0010] In one possible implementation, each superatom includes an upper I-shaped nanostructure with a thickness of t1 = 190 nm, a middle SiO2 dielectric layer with a thickness of t2 = 30 nm, and a bottom metal substrate with a thickness of t3 = 100 nm.

[0011] In one possible implementation, the material of the I-shaped nanostructure is one of Au, Ag, Al, and Na. If other materials are selected, the Drude model parameters of the metal used need to be changed, so the designed super-atom layer thickness and the parameters of the I-shaped nanostructure will change, but the parameters can be adjusted so that the working wavelength remains at the same position.

[0012] In a possible implementation, the material of the I-shaped nanostructure is Au, and the corresponding Drude model is:

[0013]

[0014] where ε(ω) is the frequency-dependent dielectric constant, ε ∞ is the limiting dielectric constant, which is 12, ω p is the plasma frequency, which is 1.37×10 16 rad / s, ω is the angular frequency of light, and γ is the electron collision frequency, which is 1.05×10 14 s -1 , i represents an imaginary number.

[0015] In a possible implementation, the I-shaped nanostructure includes a length l, a width w and a bilateral spacing d, wherein the length l represents the length of the long side of the I-shaped nanostructure, the width w represents the width of each side of the I-shaped nanostructure, the bilateral spacing d represents the interval between the two long sides of the I-shaped nanostructure, and the bilateral spacing d varies between 100 and 260 nm, the length l varies between 60 and 360 nm, and varies with the change of the geometric phase of the superatom in which the I-shaped nanostructure is located, and the width w is 60 nm.

[0016] In one possible implementation, in each supercell, the distance between the front and back superatoms is defined as the period p, and the period p of the superatom is calculated by the generalized Snell's law:

[0017]

[0018] Among them, θ r is the reflection angle of the reflected light, θ i is the angle of incidence of the incident light, is the rotation angle between adjacent superatoms, k0 is the free space wave vector, and p is the period of the superatom.

[0019] In one possible implementation, the phase of a single superatom in a supercell under left-handed light incidence is calculated by the following formula: and the phase under right-handed incident light

[0020]

[0021] in, is the transmission phase of the metaatom, and 2α is the geometric phase difference.

[0022] In one possible implementation, for any phase distribution and the required The transmission phase and rotation angle are calculated by the following formula:

[0023]

[0024] in, is the transmission phase of the superatom, and α is the rotation angle.

[0025] In a possible implementation, the central wavelength of the incident visible light is 632.8 nm, and the period p of the superatom is 380 nm.

[0026] In a possible implementation, the area S of the metasurface is ≥ (17λ) 2 , λ is the wavelength of incident visible light.

[0027] The design principle and beneficial effects of this utility model are as follows:

[0028] The utility model uses supercells formed by superatoms (composed of 8 different superatoms according to a certain rule, the next superatom in each supercell rotates 11.25° counterclockwise compared to the previous superatom, and the size of the next superatom in each supercell changes compared to the previous superatom) to construct plasma supersurfaces to design left-handed and right-handed light beam chiral deflection devices. The superatom as a whole is equivalent to a half-wave plate, so the thickness of the middle SiO2 dielectric layer t2=30nm, the thickness of the upper I-shaped nanostructure t1=190nm, and the bottom is a metal substrate with a thickness that satisfies total reflection, such as t3=100nm. Through the above principle, on the basis of ensuring that the reflection amplitude is high enough, by scanning parameters, changing the length l, width w and bilateral spacing d of the I-shaped nanostructure, the transmission phase of the superatom to left-handed and right-handed light can be dynamically changed. By adjusting the width w to 60nm, the length l between 60 and 360nm, and the bilateral spacing d between 100 and 260nm, a series of meta-atoms with transmission phases varying between 0° and 180° are obtained. Combined with the PB phase principle, each meta-atom with different transmission phases is rotated to obtain a geometric phase difference of 2α, and then any LCP (left-handed light) and RCP (right-handed light) phase distribution can be achieved. Starting from the generalized Snell's law, for example, by setting the left-hand deflection angle to 16° and the right-hand deflection angle to 0° in the case of normal incidence, and by calculating the phase distribution required for LCP and RCP, the phase distribution at each position of the metasurface is substituted into the corresponding formula to calculate the transmission phase. and the rotation angle α, and further changing the length l and the bilateral spacing d of the I-beam to obtain 8 different transmission phases By rotating the calculated angles, we can get the required 8 superatoms. After supercells are formed by arranging superatoms with corresponding phases, the supercells are arranged periodically to obtain a metasurface. For left-handed light incidence, the next superatom in each supercell produces a -22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a -180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° caused by the size change of superatoms in each supercell, the metasurface forms a phase gradient in the horizontal direction for left-handed light, presenting an abnormal deflection. For right-handed light incidence, the next superatom in each supercell produces a +22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a +180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° caused by the size change of superatoms in each supercell, the metasurface has no phase gradient for right-handed light, presenting a mirror deflection, and can achieve the predetermined function (i.e., 16° left-handed deflection and no right-handed deflection). The chiral deflection device of left- and right-handed optical beams based on a plasma metasurface designed in this way can work in the optical band and has the chiral function of decoupling left- and right-handed optical waves. The realization of the chiral function utilizes the coordinated regulation of the transmission phase and the geometric phase by the meta-atom, so that the meta-surface does not form a phase gradient for right-handed light, but forms a phase gradient in the horizontal direction for left-handed light. Therefore, when right-handed light is incident on the meta-surface, the reflected beam undergoes normal mirror reflection according to the conventional Snell's law; and when left-handed light is incident, the reflected beam undergoes abnormal non-mirror reflection at a certain angle according to the generalized Snell's law. The utility model can selectively deflect the hand-rotating light, realize the chiral function, and provide a new dimension for optical applications. The utility model can work in the optical band and has a wide range of applications. By precisely controlling the size and arrangement of the meta-atoms, the transmission phase and the geometric phase can be adjusted with high precision, thereby achieving a specific phase gradient. The meta-surface has high flexibility and can be customized according to different application requirements. The utility model can be applied to beam shaping, polarization control, photonic crystals and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the three-dimensional structure of a superatom according to an embodiment of the present invention.

[0030] Figure 2 FIG. 1 is a schematic diagram of a top-down structure of a superatom according to an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of the normalized reflection amplitude and phase after RCP and LCP incident on different metaatoms.

[0032] Figure 4 Schematic diagram of 8 superatoms.

[0033] Figure 5 Schematic diagram of the arrangement of superatoms forming supercells on the supersurface in this embodiment.

[0034] Figure 6 Schematic diagram of incident light and reflected light in this embodiment.

[0035] Figure 7 This is the phase distribution diagram of the metasurface.

[0036] Figure 8 Schematic diagram of numerical simulation of left-handed and right-handed light when the incident wavelength is 632.8nm and the incident angle range is -23°, 0°, and +23°.

[0037] Fig. 9 This is a schematic diagram of the pure device structure of the utility model. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the utility model more clear, the following embodiments will further illustrate the utility model in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0039] like Fig. 9 The present utility model provides a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface, comprising:

[0040] A supersurface 01, wherein the supersurface 01 is formed by a plurality of supercells 02 arranged in a periodic manner, wherein each supercell 02 comprises 8 superatoms 03, namely: the first superatom 03A, the second superatom 03B, the third superatom 03C, the fourth superatom 03D, the fifth superatom 03E, the sixth superatom 03F, the seventh superatom 03G, and the eighth superatom 03H; in each supercell, the 8 superatoms are arranged according to a specific rule and rotated by a certain angle, and the sizes of the 8 superatoms also change regularly; in each supercell, the latter superatom is rotated 11.25° counterclockwise compared to the former superatom, specifically, the second superatom 03B is rotated 11.25° counterclockwise compared to the first superatom 03A, the third superatom 03C is rotated 11.25° counterclockwise compared to the second superatom 03B, and so on;

[0041] The size of the next superatom in each supercell changes compared to the previous superatom;

[0042] For left-handed light incident, the last superatom in each supercell generates a -22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell generates a -180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° generated by the size change of superatoms in each supercell, the metasurface forms a phase gradient in the horizontal direction for left-handed light, thereby presenting an abnormal deflection. Specifically, the second superatom 03B generates a -22.5° geometric phase difference with respect to the first superatom 03A, and the third superatom 03C generates a -22.5° geometric phase difference with respect to the second superatom 03B. By analogy, the last eighth superatom 03H in each supercell generates a -180° geometric phase difference with respect to the first superatom 03A. Combined with the transmission phase difference of -180° generated by the size change of superatoms in each supercell, the metasurface forms a phase gradient in the horizontal direction for left-handed light, thereby presenting an abnormal deflection.

[0043] For right-handed light incident, the last superatom in each supercell generates a geometric phase difference of +22.5° relative to the previous superatom, and the last superatom in each supercell generates a geometric phase difference of +180° relative to the first superatom, combined with the transmission phase difference of -180° generated by the size change of superatoms in each supercell, so that the metasurface has no phase gradient for right-handed light, thereby presenting a mirror deflection effect. Specifically, the second superatom 03B generates a geometric phase difference of +22.5° relative to the first superatom 03A, the third superatom 03C generates a geometric phase difference of +22.5° relative to the second superatom 03B, and so on. The last eighth superatom 03H in each supercell generates a geometric phase difference of +180° relative to the first superatom 03A, combined with the transmission phase difference of -180° generated by the size change of superatoms in each supercell, so that the metasurface has no phase gradient for right-handed light, thereby presenting a mirror deflection effect.

[0044] Figure 1 and 2 Schematic diagram of the structure of a certain super atom 03. In a possible implementation, each super atom comprises an upper I-shaped nanostructure 03-1, a middle SiO2 dielectric layer 03-2 and a bottom metal substrate 03-3; the thickness of the I-shaped nanostructure 03-1 is t1=190nm, the thickness of the SiO2 dielectric layer 03-2 is t2=30nm, the thickness of the metal substrate 03-3 is sufficient for total reflection, the thickness of the metal substrate 03-3 is t3=190nm, and the period of the super atom is 380nm.

[0045] The I-shaped nanostructure 03-1 includes a length l, a width w and a bilateral spacing d, wherein the length l represents the length of the long side of the I-shaped nanostructure 03-1, the width w represents the width of each side of the I-shaped nanostructure 03-1, and the bilateral spacing d represents the interval between the two long sides of the I-shaped nanostructure 03-1.

[0046] The I-shaped nanostructure 03-1 can be one of Au I-shaped nanostructure, Ag I-shaped nanostructure, Al I-shaped nanostructure, and Na I-shaped nanostructure. When the I-shaped nanostructure 03-1 is Au I-shaped nanostructure, the corresponding Drude model is:

[0047]

[0048] where ε(ω) is the frequency-dependent dielectric constant, ε ∞ is the limiting dielectric constant, which is 12, ω p is the plasma frequency, which is 1.37×1016rad / s, ω is the angular frequency of light, and γ is the electron collision frequency, which is 1.05×1014s -1 , i represents an imaginary number.

[0049] Based on the above principle, on the basis of ensuring that the reflection amplitude is high enough, the transmission phase of the super atom 03 for left-handed and right-handed light is dynamically changed by scanning parameters, changing the length l, width w and bilateral spacing d of the I-shaped nanostructure 03-1. By adjusting the width w of the I-shaped nanostructure 03-1 to 60nm, the bilateral spacing d to vary between 100 and 260nm, and the length l to vary between 60 and 360nm, a series of super atoms 03 with transmission phases varying between 0° and 180° are obtained.

[0050] Combining the PB phase principle, by rotating each metaatom with different transmission phase to obtain a geometric phase difference of 2α, arbitrary LCP (left-handed light) and RCP (right-handed light) phase distributions can be achieved.

[0051] Specifically, in order to impose independent phase distribution on orthogonal circularly polarized channels, it is necessary to combine the transmission phase and geometric phase to decouple the mutual relationship between LCP waves and RCP waves. Based on the Jones matrix analysis, when the meta-atom with half-wave plate effect When rotating, the circular polarization phase is described by the following formula:

[0052]

[0053] in, is the phase of a single superatom in the supercell under left-handed light incidence, is the phase of a single superatom in the supercell under right-handed light incidence, is the transmission phase of the superatom, 2α is the geometric phase difference, and α refers to the rotation angle.

[0054] Combining the above equations, we can get any phase distribution and the required On this basis, the calculation formula for transmission phase and rotation angle is obtained:

[0055]

[0056] Based on this, any phase distribution of LCP and RCP can be achieved.

[0057] The period p of a hyperatom can be calculated using the generalized Snell's law:

[0058]

[0059] Among them, θ r is the reflection angle of the reflected light, θ i is the angle of incidence of the incident light, is the rotation angle between adjacent superatoms, k0 is the free space wave vector, and p is the period of the superatom, which represents the distance between the next superatom and the previous superatom in the supercell.

[0060] If you want to achieve a left-hand deflection angle of 16° and a right-hand deflection angle of 0° under normal incidence, then the phase distribution required for LCP and RCP is calculated by the formula: Figure 3 shown. Figure 3 Schematic diagram of the normalized reflection amplitude and phase after RCP and LCP incident on different superatoms, where Figure 3 Figures (a) and (b) in the figure are schematic diagrams of the normalized reflection amplitude and phase after RCP light is incident on different superatoms. Figure 3 Figures (c) and (d) are schematic diagrams of the normalized reflection amplitude and phase after LCP light is incident on different metaatoms.

[0061] Substituting the phase distribution at each position of the metasurface into formula (4) and formula (5), the transmission phase is calculated and the rotation angle α, and further changing the length l and the bilateral spacing d of the I-beam to obtain 8 different transmission phases The required 8 superatoms can be obtained by adding superatoms, such as Figure 4As shown in the first superatom 03A to the eighth superatom 03H in (in this embodiment, the parameters of the I-shaped nanostructures of the eight superatoms 1 to 8 obtained are: the first superatom 03A, the I-shaped nanostructure length l is 65nm, the width w is 60nm, and the bilateral spacing d is 60nm; the second superatom 03B, the I-shaped nanostructure length l is 85nm, the width w is 60nm, and the bilateral spacing d is 60nm; the third superatom 03C, the I-shaped nanostructure length l is 173nm, the width w is 60nm, and the bilateral spacing d is 60nm; the fourth superatom 03D, the I-shaped nanostructure length l is The length of the I-shaped nanostructure is 190nm, the width w is 60nm, and the bilateral spacing d is 60nm; the fifth superatom 03E, the length l of the I-shaped nanostructure is 210nm, the width w is 60nm, and the bilateral spacing d is 60nm; the sixth superatom 03F, the length l of the I-shaped nanostructure is 238nm, the width w is 60nm, and the bilateral spacing d is 60nm; the seventh superatom 03G, the length l of the I-shaped nanostructure is 318nm, the width w is 60nm, and the bilateral spacing d is 60nm; the eighth superatom 03H, the length l of the I-shaped nanostructure is 360nm, the width w is 60nm, and the bilateral spacing d is 60nm). Then, by rotating the calculated angle obtained by arranging the corresponding phase superatoms, the final supersurface distribution can be obtained: composed of 8 different superatoms according to a certain rule, the next superatom in each supercell rotates 11.25° counterclockwise compared to the previous superatom, and the size of the next superatom in each supercell changes compared to the previous superatom, forming a supercell, and then the supercells are arranged periodically to form a supersurface. In this way, the predetermined function can be achieved, that is, the left-hand deflection is 16°, and the right-hand deflection is not deflected.

[0062] For example, for left-handed light incident, the next superatom in each supercell produces a -22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a -180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° caused by the size change of superatoms in each supercell, the metasurface forms a phase gradient in the horizontal direction for left-handed light, presenting an abnormal deflection; for right-handed light incident, the next superatom in each supercell produces a +22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a +180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° caused by the size change of superatoms in each supercell, the metasurface has no phase gradient for right-handed light, presenting a mirror deflection. Based on this, a left-handed and right-handed light beam chiral deflection device based on a plasma metasurface can be constructed, such as Figure 5 As shown, Figure 5 Schematic diagram of the arrangement of superatoms forming supercells on the supersurface in this embodiment.

[0063] The following structural principles verify the technical solution and technical effects of the utility model:

[0064] like Figure 6 As shown, Figure 6 Schematic diagram of incident light and reflected light in this embodiment. Assuming the area of ​​the metasurface S ≥ (17λ) 2 , λ is the wavelength of incident visible light, taking the period of the super atom as 380nm as an example, see Figure 3 , 7 , 8, Figure 7 This is a phase distribution diagram of the metasurface, where the left figure is the phase distribution of left-handed light. The intervals of different colors represent phase changes from 0° to 360°, divided into eight intervals at 45° intervals. The intervals of different colors also represent meta-atoms with different phases, which will produce a specific phase gradient when left-handed light is incident, thereby guiding the beam deflection. The right figure shows a uniform color block for right-handed light, which may mean that for right-handed light, the phase distribution of the metasurface is uniform and will not produce additional phase gradients for right-handed light, so it will only produce normal reflection.

[0065] This design cleverly utilizes the chiral properties of the metasurface, and can differentiate light beams of different chirality by precisely controlling the phase of each metaatom. This property is expected to promote the development of new devices in the field of optics, such as optical communications, quantum information processing, and biosensing, which have potential application value.

[0066] Figure 8 The figure is a numerical simulation diagram of left-handed and right-handed light when the incident wavelength is 632.8nm and the incident angle range is -23°, 0°, and +23°. It can be seen that at the same incident angle, left-handed light will carry an extra angle, resulting in an abnormal reflection effect, while right-handed light has no extra angle and produces a normal reflection effect.

[0067] In summary, the embodiment of the utility model provides a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface, and uses a supercell formed by superatoms to construct a plasma metasurface to design a left-handed and right-handed optical beam chiral deflection device. The superatom is equivalent to a half-wave plate as a whole, so the thickness of the middle SiO2 dielectric layer t2=30nm, the thickness of the upper I-shaped nanostructure t1=190nm, and the bottom is a metal substrate, and the thickness satisfies total reflection, such as t3=100nm. Through the above principle, on the basis of ensuring that the reflection amplitude is high enough, by scanning parameters, changing the length l, width w and bilateral spacing d of the I-shaped nanostructure, the transmission phase of the superatom to left-handed and right-handed light can be dynamically changed. By adjusting the width w to 60nm, the bilateral spacing d between 100 and 260nm, and the length l between 60 and 360nm, a series of meta-atoms with transmission phases varying between 0° and 180° are obtained. Combined with the PB phase principle, each meta-atom with different transmission phases is rotated to obtain a geometric phase difference of 2α, and then any LCP (left-handed light) and RCP (right-handed light) phase distribution can be achieved. Starting from the generalized Snell's law, for example, by setting the left-hand deflection angle to 16° and the right-hand deflection angle to 0° in the case of normal incidence, and by calculating the phase distribution required for LCP and RCP, the phase distribution at each position of the metasurface is substituted into the corresponding formula to calculate the transmission phase. and the rotation angle α, and further changing the length w and the bilateral spacing d of the I-beam to obtain eight different transmission phases By rotating the calculated angles, we can get the required eight superatoms. After supercells are formed by arranging superatoms with corresponding phases, the supercells are arranged periodically to obtain a metasurface. For left-handed light incidence, the next superatom in each supercell produces a -22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a -180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° caused by the size change of superatoms in each supercell, the metasurface forms a phase gradient in the horizontal direction for left-handed light, presenting an abnormal deflection. For right-handed light incidence, the next superatom in each supercell produces a +22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a +180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° caused by the size change of superatoms in each supercell, the metasurface has no phase gradient for right-handed light, presenting a mirror deflection, and can achieve the predetermined function (i.e., 16° left-handed deflection and no right-handed deflection). The chiral deflection device for left- and right-handed optical beams based on a plasma metasurface designed in this way can operate in the optical band and has the chiral function of decoupling left- and right-handed optical waves. The realization of the chiral function utilizes the coordinated regulation of the transmission phase and the geometric phase by meta-atoms, so that the metasurface does not form a phase gradient for right-handed light, but forms a phase gradient in the horizontal direction for left-handed light. Therefore, when right-handed light is incident on the metasurface, the reflected beam undergoes normal mirror reflection according to the conventional Snell's law; and when left-handed light is incident, the reflected beam undergoes abnormal non-mirror reflection at a certain angle according to the generalized Snell's law.

[0068] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface, characterized in that: include: The supersurface is composed of several supercells arranged periodically, wherein each supercell is composed of 8 superatoms, the next superatom in each supercell rotates 11.25° counterclockwise compared to the previous superatom, and the size of the next superatom in each supercell changes compared to the previous superatom; For left-handed light, the last superatom in each supercell produces a -22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a -180° geometric phase difference with respect to the first superatom. Combined with the -180° transmission phase difference caused by the size change of superatoms in each supercell, the metasurface forms a phase gradient in the horizontal direction for left-handed light, showing abnormal deflection. For right-handed light incident, the last superatom in each supercell produces a +22.5° geometric phase difference with respect to the previous superatom, and the last superatom in each supercell produces a +180° geometric phase difference with respect to the first superatom. Combined with the transmission phase difference of -180° caused by the size change of superatoms in each supercell, the metasurface has no phase gradient for right-handed light and exhibits mirror deflection.

2. According to claim 1, a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface is characterized in that: Each superatom consists of three layers: the upper I-shaped nanostructure with a thickness of t1 = 190nm; the middle SiO2 dielectric layer with a thickness of t2 = 30nm; and the bottom metal substrate with a thickness of t3 = 100nm.

3. According to claim 2, a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface is characterized in that: The I-shaped nanostructure adopts a gold I-shaped nanostructure; the limiting dielectric constant is 12; the plasma frequency is 1.37×10 16 rad / s, the electron collision frequency is 1.05×10 14 s -1 .

4. According to claim 2, a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface is characterized in that: The I-shaped nanostructure comprises a length l, a width w and a bilateral spacing d, wherein the length l represents the length of the long side of the I-shaped nanostructure, the width w represents the width of each side of the I-shaped nanostructure, the bilateral spacing d represents the interval between the two long sides of the I-shaped nanostructure, and the bilateral spacing d varies between 100 and 260 nm, the length l varies between 60 and 360 nm, and varies with the change of the geometric phase of the superatom in which the I-shaped nanostructure is located, and the width w is 60 nm.

5. According to claim 1, a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface is characterized in that: The area of ​​the metasurface S ≥ (17λ) 2 , λ is the wavelength of incident visible light.

6. According to claim 5, a left-handed and right-handed optical beam chiral deflection device based on a plasma metasurface is characterized in that: The central wavelength of the incident visible light is 632.8 nm. In each supercell, the distance between the front and rear superatoms is defined as a period p, and the period p of the superatom is 380 nm.

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