All-dielectric metasurface polarizer with high transmittance

Abstract

The invention provides an all-dielectric metasurface polarizer with high transmittance. The all-dielectric metasurface polarizer comprises a substrate and a periodic array structure prepared on the substrate, each unit period of the periodic array structure comprises a cross-shaped nano structure and a circular ring type nano structure. According to the invention, the index requirements of high transmittance and stable output in the visible light band and the near-infrared band provide a good theoretical basis for the research of subsequent metasurface devices.

Description

Technical Field

[0001] The present invention relates to the technical field of applied optical devices, and in particular to an all-dielectric metasurface polarizer with high transmittance. Background Art

[0002] Metasurfaces are composed of specific subwavelength units on a two-dimensional plane. As planar optical elements, they have attracted widespread attention. They provide a new paradigm for designing ultra-compact optical components and have great potential in lightweighting and miniaturization of optical systems. In the past few decades, metasurfaces have attracted widespread attention from multiple disciplines due to their rich functions and ability to manipulate various parameters of light waves. Among them, polarization control at the subwavelength scale is an outstanding capability of metasurfaces compared with traditional optical elements. However, due to the inherent Ohmic loss of plasmonic metasurfaces, their low efficiency has seriously hindered their widespread application. Therefore, it is necessary to design all-dielectric metasurface devices with high transmission efficiency. Summary of the invention

[0003] In order to solve the technical problems in the prior art that polarization devices have poor structural stability and are difficult to ensure transmittance in the visible light band and near-infrared band, an object of the present invention is to provide an all-dielectric metasurface polarizer with high transmittance, the all-dielectric metasurface polarizer comprising a substrate and a periodic array structure prepared on the substrate;

[0004] Each unit period of the periodic array structure includes a cross-shaped nanostructure and a ring-shaped nanostructure.

[0005] Preferably, the substrate is a SiO2 substrate, and the cross-shaped nanostructure and the ring-shaped nanostructure are made of Si3N4 material.

[0006] The present invention provides a highly transmittance all-dielectric metasurface polarizer, which designs cross-shaped and ring-shaped nanostructures on the unit period to regulate the transmission efficiency of the incident wave, achieve high transmittance performance of polarized light, and ensure structural stability. Simulation results show that the periodic array structure can achieve a transmittance of 98% in the visible light band and 96% in the near-infrared band, meeting the measurement requirements.

[0007] The present invention provides an all-dielectric metasurface polarizer with high transmittance, which meets the index requirements of high transmittance and stable output in the visible light band and near-infrared band, and provides a good theoretical basis for the subsequent research on metasurface devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0009] Figure 1 The structural diagram of an all-dielectric metasurface polarizer with high transmittance of the present invention is schematically shown.

[0010] Figure 2 A simulation model diagram of a unit periodic unit of a periodic array structure of an all-dielectric metasurface polarizer with high transmittance according to the present invention is shown.

[0011] Figure 3 A comparison chart of transmittance and reflectance results of an all-dielectric metasurface polarizer with high transmittance in the 450-850nm band is shown.

[0012] Figure 4 A comparison diagram of the electric field intensity distribution of an all-dielectric metasurface polarizer with high transmittance in different bands of the present invention is shown. DETAILED DESCRIPTION

[0013] In order to make the above and other features and advantages of the present invention more clear, the present invention is further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are only exemplary and not restrictive.

[0014] Combination Figure 1 According to an embodiment of the present invention, there is provided an all-dielectric metasurface polarizer with high transmittance, comprising a substrate and a periodic array structure prepared on the substrate.

[0015] Each unit period of the periodic array structure includes a cross-shaped nanostructure 100 and a ring-shaped nanostructure 200. The substrate is a SiO2 substrate, and the cross-shaped nanostructure 100 and the ring-shaped nanostructure 200 are made of Si3N4 material.

[0016] Figure 1 (a) is an all-dielectric metasurface polarizer with high transmittance, (b) is a top view of a cross-shaped nanostructure 100 and a circular ring-shaped nanostructure 200 of a unit period, and (c) is a stereoscopic view of a cross-shaped nanostructure 100 and a circular ring-shaped nanostructure 200 of a unit period.

[0017] Figure 1 In the figure, Lx*Ly represents the x-axis and y-axis dimensions of a unit period;

[0018] d c represents the length of the cross-shaped nanostructure 100, and the dimensions of the cross-shaped nanostructure 100 along the x-axis and the y-axis are the same;

[0019] w represents the line width of the cross-shaped nanostructure 100;

[0020] r out represents the outer diameter of the ring-shaped nanostructure 200, r in represents the inner diameter of the donut-shaped nanostructure 200;

[0021] h represents the height of the cross-shaped nanostructure 100 and the ring-shaped nanostructure 200;

[0022] l rc denoted by φ( 100 ) the distance between the cross-shaped nanostructure 100 and the ring-shaped nanostructure 200 (the distance between the heterogeneous structures).

[0023] In the FDTD simulation environment (Ansys Lumerical FDTD simulation software), a simulation test is performed on an all-dielectric metasurface polarizer with high transmittance provided by the present invention.

[0024] Combination Figure 1 and Figure 2 , a simulation model of a unit periodic unit of a periodic array structure of an all-dielectric metasurface polarizer with high transmittance of the present invention is established. Figure 2 (a) is a top view of the simulation model of the cross-shaped nanostructure 100 and the ring-shaped nanostructure 200 of one unit period, and (b) is a stereoscopic view of the simulation model of the cross-shaped nanostructure 100 and the ring-shaped nanostructure 200 of one unit period.

[0025] Lumerical FDTD Solutions simulation software was used to establish a periodic subwavelength all-dielectric nanomodel with different structural parameters on the surface of the silicon dioxide substrate. The simulation parameters were set as follows:

[0026] The wavelength of the incident light is in the range of 450-850nm, and the dimensions Lx and Ly in the x-axis direction and y-axis direction of a unit period are 1um and 500nm respectively.

[0027] The line width w of the cross-shaped nanostructure 100 is set to 100 nm, the height h of the cross-shaped nanostructure 100 and the ring-shaped nanostructure 200 is set to 280 nm, and the length d of the cross-shaped nanostructure 100 is set to 280 nm. c The distance l between the cross-shaped nanostructure 100 and the ring-shaped nanostructure 200 is set to 400 nm. rc The distance is set to 150nm, and the outer diameter r of the ring-shaped nanostructure 200out , the inner diameter r of the annular nanostructure 200 in Set to 150nm and 50nm respectively.

[0028] The transmittance and reflectance results obtained by simulation are as follows Figure 3 As shown, it can be seen that in the range of 450-700nm, the overall transmittance of the polarizer exceeds 90%, and can reach 98% transmittance at a wavelength of 500nm. In the near-infrared band (800-850nm), the polarizer also exhibits an efficient transmittance performance of 95%.

[0029] The simulation results show that the electric field intensity distribution under different bands is relatively Figure 4 As shown, Figure 4 (a) is the electric field distribution at 500nm, and (b) is the electric field distribution at 850nm.

[0030] At 500nm, the modulation of polarized light in the transmission direction by the polarizer was observed, indicating that the structure has strong resonance in the visible light band and is dominant around the structure. At a wavelength of 850nm, we found that the mutually perpendicular structures have a modulating effect on polarized light, while the resonance effect of the ring structure is not obvious, but it has the effect of stabilizing the waveform.

[0031] According to the simulation data, the transmittance and reflectance curves in the 450-850nm band are obtained, and the electric field distribution diagrams in different bands are obtained. At 500nm, the transmittance of the all-dielectric metasurface polarizer to polarized light is as high as 98%, and the transmittance of polarized light in the near-infrared range can also maintain an efficient transmission of more than 90%. It can be considered that the transmission effect of the metasurface polarizer of this structure is significant, meeting the current application requirements of miniaturization and integration with high transmission efficiency.

[0032] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An all-dielectric metasurface polarizer with high transmittance, characterized in that: The all-dielectric metasurface polarizer includes a substrate and a periodic array structure prepared on the substrate; Each unit period of the periodic array structure includes a cross-shaped nanostructure and a ring-shaped nanostructure.

2. The all-dielectric metasurface polarizer according to claim 1, characterized in that: The substrate is a SiO2 substrate, and the cross-shaped nanostructure and the ring-shaped nanostructure are made of Si3N4 material.

Images