Polarization adjustable spin decoupling metasurface based on perovskite material

Abstract

The invention provides a polarization adjustable spin decoupling metasurface based on a perovskite material. The metasurface is characterized in that the metasurface is of a three-layer structure, namely a perovskite and metal pattern layer (1), an intermediate dielectric layer (2) and a reflection bottom layer (3) from top to bottom in sequence. When the perovskite is in a metal state, the designed metasurface can independently adjust left-handed and right-handed circularly polarized light; when the perovskite is in an insulated state, the designed metasurface can independently adjust x and y linear polarized light; by switching the state of the perovskite, the phases of the circularly polarized light and the linearly polarized light can be regulated and controlled at the same time, so that different functions are realized. The optical metasurface designed by the invention has huge potential in a terahertz frequency band, and can be widely applied to beam shaping, holographic imaging, information encryption, super lenses and the like.

Description

(1) Technical Field

[0001] The present invention relates to a polarization - tunable spin - decoupled metasurface based on perovskite materials, belonging to the field of optical metamaterials. It can be applied to fields such as optical imaging, information encryption, and quantum communication. (2) Background Art

[0002] With the continuous development of optical technologies, the requirements for the manipulation accuracy and functions of light are getting higher and higher. Especially in the fields of optical imaging, information encryption, quantum communication, etc., it is necessary to be able to efficiently and flexibly manipulate the polarization state and phase of light. In recent years, as an emerging optical technology, the metasurface technology has received extensive attention due to its high - efficiency light - control ability at the sub - wavelength scale. The metasurface is composed of periodic structures at the sub - wavelength scale, which can achieve precise control of the amplitude, phase, and polarization state of light, providing new possibilities for the design and application of optical devices.

[0003] Perovskite materials have become a research hotspot in the optical field due to their excellent optical properties, such as high refractive index, high absorption coefficient, tunable bandgap, etc. Perovskite materials not only have good optical characteristics but also have tunable physical properties, which makes them have broad application prospects in optical metasurfaces. However, traditional metasurface designs usually can only achieve the control of a single polarization state and it is difficult to independently manipulate multiple polarization states simultaneously. In addition, once the performance of the metasurface is designed, it is usually difficult to dynamically adjust, which limits its flexibility in practical applications.

[0004] The emergence of spin - decoupling technology provides a new idea to solve this problem. Through spin - decoupling, independent manipulation of light with different spin states can be achieved, thereby improving the performance and functions of optical systems. The spin - decoupled metasurface can simultaneously perform phase control on circularly polarized light and linearly polarized light, and can independently modulate the phases of different polarization states, which provides new technical means for fields such as optical encryption, holographic imaging, and quantum communication.

[0005] The present invention proposes a polarization - tunable spin - decoupled metasurface based on perovskite materials. This metasurface utilizes the tunable characteristics of perovskite materials and combines spin - decoupling technology to achieve dynamic control of multiple polarization states. By designing a specific metasurface structure, the present invention can simultaneously achieve a 0 - 2π phase coverage for circularly polarized light and linearly polarized light, and can independently control the phases in the x and y polarization directions. This metasurface structure is simple and its performance is adjustable. It can not only achieve efficient optical information processing but also has significant application advantages in fields such as holographic imaging, information encryption, and quantum communication. (3) Summary of the Invention

[0006] A polarization-tunable spin-decoupled metasurface based on perovskite materials. The designed pattern combines an outer metal rod with an inner perovskite cross structure, enabling phase modulation of left-handed, right-handed circularly polarized light and x, y linearly polarized light in the terahertz frequency band, thus achieving different functions.

[0007] The object of the present invention is achieved as follows:

[0008] The metasurface consists of three layers, which are closely attached to each other. From top to bottom, they are a perovskite and gold pattern layer (1) with tunable characteristics, a polyimide dielectric layer (2), and a gold reflective bottom layer (3).

[0009] Preferably, the optimal parameters are obtained as follows: the period P = 100 um, the thickness t of the gold reflective bottom layer = 0.5 um, the thickness h of the dielectric layer = 30 um, and the thickness t of the top layer = 0.5 um.

[0010] Preferably, the optimal parameters are obtained as follows: the width w1 of the outer metal rod = 5 um, and the transverse length and longitudinal length of the inner perovskite cross structure are l x and l y , and the width w2 = 10 um.

[0011] Preferably, by changing the conductivity of the perovskite material to switch its state, the modulation of different polarized lights is achieved; the transverse length l x and longitudinal length l y of the outer metal rod are respectively used to modulate the phases of x linearly polarized light and y linearly polarized light, and the rotation angle of the inner perovskite cross structure is used to modulate the phases of left-handed and right-handed circularly polarized light by means of the spin-decoupling principle. (IV) BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a three-dimensional structure schematic diagram of a polarization-tunable spin-decoupled metasurface based on perovskite materials.

[0013] Figure 2 is a top view of a polarization-tunable spin-decoupled metasurface based on perovskite materials.

[0014] Figure 3 is the phase of the first-order vortex light achieved when left-handed circularly polarized light is incident on the metasurface when the conductivity of the perovskite is designed to be high conductivity and it is in the metallic state.

[0015] Figure 4 is the phase of the second-order vortex light achieved when right-handed circularly polarized light is incident on the metasurface when the conductivity of the perovskite is designed to be high conductivity and it is in the metallic state.

[0016] Figure 5It is the 1900mm focusing achieved when the perovskite is in an insulating state with a designed low conductivity and x-polarized light is incident on the metasurface.

[0017] Figure 6 It is the 1000mm focusing achieved when the perovskite is in an insulating state with a designed low conductivity and y-polarized light is incident on the metasurface. (V) Specific implementation manners

[0018] The following further explains the specific measures of the present invention in conjunction with the accompanying drawings.

[0019] Figure 1 、 2 The polarization-tunable spin-decoupled metasurface based on perovskite materials in the terahertz frequency band shown. The three-layer structure is closely attached to each other. From top to bottom, they are the perovskite and gold pattern layer (1) with tunable characteristics, the polyimide dielectric layer (2), and the gold reflective bottom layer (3).

[0020] As one of the eight unit structures of the metasurface, the size of each metasurface unit structure is as follows; the period P = 100um, the thickness t of the gold reflective bottom layer = 0.5um, the thickness h of the dielectric layer = 30um, and the thickness t of the top layer = 0.5um. The width w1 of the outer metal rod = 5um, and the transverse length and longitudinal length of the inner perovskite cross structure are l x and l y , and the width w2 = 10um.

[0021] Regarding the spin decoupling of circular polarization, it can be calculated by the following formula: where is the phase of the right-handed circularly polarized light, is the phase of the left-handed circularly polarized light. Figure 3 and Figure 4 respectively show the phases of the vortex light achieved when the perovskite is in a metallic state with a designed high conductivity and left- and right-handed circularly polarized lights are incident on the metasurface.

[0022] Through simulation, the focusing functions achieved when the perovskite is in an insulating state with a designed low conductivity and x- and y-polarized lights are incident on the metasurface as shown in Figure 5 and 6 are obtained.

[0023] The working principle of the polarization-tunable spin-decoupled metasurface based on perovskite materials is based on the interaction between the metasurface with subwavelength structure and light waves, as well as the precise control of the light wavefront phase by the special structural design of the metasurface. When light with different polarization states is incident on the metasurface, its electric field distribution has specific polarization characteristics. To achieve independent control of different polarization states, the metasurface needs to achieve phase control at different positions, so as to form the required polarization state distribution on the output surface. The design of the metasurface includes periodically arranged metal rods and perovskite cross structures. By changing their sizes and arrangement patterns, different phase delays can be generated for light waves. Especially for the perovskite cross structure, its rotation angle can achieve fine control of the phase change. During the optimization process, according to the electric field intensity amplitude distribution of the target polarization state and the electric field intensity distribution after the incident light passes through the metasurface, the phase distribution of the metasurface is continuously optimized through an iterative algorithm until the expected control effect is achieved. By changing the sizes and arrangements of the unit structures, precise control of the phase distribution of the metasurface can be realized, thereby achieving efficient polarization state control.

Claims

1. Polarization-tunable spin-decoupled metasurface based on perovskite materials, characterized by: From top to bottom, there are perovskite material and gold hybrid pattern layer (1), polyimide dielectric layer (2), and gold reflective bottom layer (3), and each layer is tightly fitted to each other; the lateral and longitudinal periods of the entire structure are both P = 100um, and the thickness of the bottom metal reflective layer is t = 0.5um. To ensure that the reflective layer can completely reflect electromagnetic waves, its thickness is much greater than the skin depth of the electromagnetic waves. The thickness of the polyimide dielectric layer is h = 30um, and the dielectric constant is ε = 3.

5.

2. The polarization-tunable spin-decoupling metasurface based on perovskite material according to claim 1, characterized in that: The upper layer of perovskite material and metal pattern consists of an outer metal rod and an inner perovskite cross structure. The top layer thickness is t = 0.5um, the outer metal rod width is w1 = 5um, and the lateral and longitudinal lengths of the inner perovskite cross structure are l x and l y , width w2=10um.

3. According to the polarization-adjustable spin-decoupled metasurface based on perovskite material in claim 1, the state of the perovskite material is switched by changing the conductivity of the perovskite material to achieve the regulation of different polarized light; the lateral length l of the outer metal rod is used x and longitudinal length l y The phases of x-polarized light and y-polarized light are regulated respectively, and the rotation angle of the inner perovskite cross structure is The phase of left-handed and right-handed circularly polarized light is controlled using the principle of spin decoupling.

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