A method for realizing full polarizer based on multi-layered external chiral metasurface

Abstract

The present invention provides a method for implementing a full polarizer based on a multi-layer outer chiral metasurface, including performing numerical calculations to simulate multi-layer U-shaped gold outer chiral metasurfaces with different parameters; then irradiating with any polarized light obliquely according to the result of the action of the full polarizer; using electron beam lithography technology to etch a U-shaped gold split-ring resonator array with a cross-section of 5*5 mm<supgt;2< / supgt; on a 1-mm-thick sheet material; and measuring the polarization state of the transmitted light. The present invention provides a new implementation method for realizing a full polarization converter and has important application prospects in application directions related to polarization control.

Description

Technical Field

[0001] The present invention provides a method for realizing a full polarizer based on a multi-layer external chiral metasurface, and belongs to the technical field of full polarizer preparation. Background Art

[0002] Polarization is an essential characteristic of electromagnetic waves. Electromagnetic waves can transmit information in different environments through different polarization states. Therefore, the control and manipulation of the polarization state of the light field is of great significance for related research in the fields of imaging, liquid crystal display, fiber optic communication and sensing. In traditional optical systems, the role of a linear polarizer is to convert incident light of any polarization state into linear polarized light. A circular polarizer is an optical element that generates circularly polarized light. It consists of a linear polarizer and a quarter wave plate.

[0003] Recent scientific research has shown that a full polarizer can be realized through a non-Hermitian system. A full polarizer is a device that produces a specific polarization output regardless of the input polarization state, and it always produces a perpendicular polarization state when transmitted from the opposite direction. However, most current research is still in the theoretical stage, and experimental proofs are mostly achieved through complex optical fiber loops. There are no reports on the experimental realization of a full polarizer in free space using metamaterials, metasurfaces and other technologies.

[0004] Most of the full polarizer research nowadays is focused on theory, while a few experiments are carried out in complex optical fiber systems. However, there are currently almost no full polarizer functions achieved through metasurfaces. Summary of the invention

[0005] The present invention aims to realize a full polarizer based on a multi-layer external chiral metasurface, that is, no matter what the input polarization state is, this device will produce the required specific polarization state output, and when transmitted from the opposite direction, it will always produce a perpendicular polarization state. This technology has great application potential in dual-channel differential polarization state communication, computing and other applications.

[0006] The specific technical solution is:

[0007] A method for realizing a full polarizer based on a multilayer external chiral metasurface comprises the following steps:

[0008] (1) Using numerical calculation, multilayer U-shaped gold external chiral metasurfaces with different parameters are simulated; then, an arbitrary beam of polarized light is irradiated obliquely according to the result of the full polarizer, where the single-layer metasurface structure size parameters are set to R = 350nm, w = 200nm and thickness is 100nm. The array period is set to P X =1000nm,P y =650nm;

[0009] (2) Using electron beam etching technology, a 5*5mm cross-section is etched on a 1mm thick sheet material. 2 The U-shaped gold split ring resonator array is made of quartz glass;

[0010] (3) A beam of white light source or laser passes through a first polarizer and a first quarter wave plate to form linear polarized light, elliptically polarized light, and circularly polarized light. The linear polarized light, circularly polarized light, and elliptically polarized light are irradiated onto the multilayer metasurface at an angle of 45° to the metasurface normal, and the polarization state of the transmitted light is measured by a second quarter wave plate, a second polarizer, and an optical power meter.

[0011] The transmission directions of the first polarizer and the second polarizer are both parallel to the symmetry axis of the U-shaped array, and the plane at an angle formed by the light source direction and the normal does not include the symmetry axis of the U-shaped array.

[0012] The technical effects of the present invention are as follows:

[0013] The present invention provides a new method for realizing a full polarization converter, and has important application prospects in the application direction related to polarization control.

[0014] Since the present invention adopts a multi-layer external chiral metasurface, it has the advantages of small structure size, simple process, easy processing, etc.

[0015] The present invention is transmissive in both directions and has important applications in future transmissive dual-channel optical paths. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of a full polarizer device of the present invention;

[0017] Figure 2 is a top view and a structural insert view of a full polarizer device of the present invention;

[0018] Figure 3 This is a diagram of the experimental setup for realizing a full polarizer;

[0019] Figure 4a The forward fully polarized evolved Poincare transmission sphere of the embodiment;

[0020] Figure 4b The reverse fully polarized evolved Poincare transmission sphere is an example of an embodiment. DETAILED DESCRIPTION

[0021] The specific technical solution of the present invention is explained in conjunction with embodiments.

[0022] A method for realizing a full polarizer based on a multilayer external chiral metasurface, the specific implementation steps are as follows:

[0023] (1) Using numerical calculations, we simulated multilayer U-shaped gold external chiral metasurfaces with different parameters, such as Figure 1 As shown; then, an arbitrary beam of polarized light is obliquely irradiated according to the result of the full polarizer, where the size parameters of the single-layer metasurface structure are set to R = 350nm, w = 200nm and the thickness is 100nm. The array period is set to P X =1000nm,P y =650nm, such as Figure 2 As shown;

[0024] (2) Using electron beam etching technology, a 5*5mm cross-section is etched on a 1mm thick sheet material. 2 The U-shaped gold split ring resonator array, the material property is quartz glass;

[0025] (3) Figure 3 As shown, a beam 3 of a white light source or a laser passes through a first polarizer 4 and a first quarter wave plate 5 to form linearly polarized light, elliptically polarized light, and circularly polarized light. The linearly polarized light, circularly polarized light, and elliptically polarized light are irradiated onto a multilayer metasurface 6 at an angle of 45° to the metasurface normal, and a second quarter wave plate 7, a second polarizer 8, and an optical power meter 9 are used to measure the polarization state of the transmitted light.

[0026] The transmission directions of the first polarizer 4 and the second polarizer 8 are both parallel to the symmetry axis of the U-shaped array, and the plane formed by the angle between the light source direction and the normal line does not include the symmetry axis of the U-shaped array.

[0027] Figure 4a and Figure 4b The Poincare transmission sphere was used to experimentally measure the forward and reverse full polarization evolution of arbitrarily polarized light with an incident angle of 45° passing through a multilayer metasurface. The direction of the evolution trajectory is indicated by an arrow, the prism is the evolution trajectory of circularly polarized light, the dark color is left-handed circularly polarized light, the light color is right-handed circularly polarized light, the circle is the evolution trajectory of linearly polarized light, the dark color is 45° polarized light evolution, and the slightly lighter color is 30° polarized light evolution.

Claims

1. A method for realizing a full polarizer based on a multilayer exo-chiral metasurface, It is characterized in that The following steps are involved: (1) Use numerical calculations to simulate multi-layer U-shaped gold external chiral metasurfaces with different parameters; then use any beam of polarized light to illuminate the surface at an angle to achieve the effect of a full polarizer. (2) Using electron beam lithography technology, a 5*5 mm cross-section was etched on a 1 mm thick sheet material. 2 The U-shaped gold split ring resonator array, the material property is quartz glass; (3), a light beam (3) of a white light source or a laser passes through a first polarizer (4) and a first quarter wave plate (5) to form linearly polarized light, elliptically polarized light or circularly polarized light; the linearly polarized light, circularly polarized light or elliptically polarized light is irradiated onto the multilayer metasurface (6) at an angle of 45° to the metasurface normal, the transmission directions of the first polarizer (4) and the second polarizer (8) are both parallel to the direction of the symmetry axis of the U-shaped array, and the plane at which the angle between the light source direction and the normal does not include the symmetry axis of the U-shaped array.

2. A method for realizing a full polarizer based on a multilayer external chiral metasurface according to claim 1, It is characterized in that In step (1), the metasurface structure size parameters are set to the curvature radius R = 350nm of the U-shaped arc part, the width and length w = 200nm and the thickness of the straight line parts at both ends of the U-shaped part are 100nm. The array period is set to P X =1000nm, P y =650nm.

3. The method for realizing a full polarizer based on a multilayer external chiral metasurface according to claim 1, It is characterized in that In step (2), the sheet material is quartz glass.

4. The method for realizing a full polarizer based on a multilayer external chiral metasurface according to claim 1, It is characterized in that The polarization state of the transmitted light is measured using a second quarter wave plate (7), a second polarizer (8) and an optical power meter (9).

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