Grating polarizer

Abstract

The invention relates to a grating polarizer, which comprises a substrate and a plurality of grating structures, wherein the grating structures are periodically arranged on the substrate; each grating structure comprises a dielectric layer, a first metal layer and a second metal layer respectively; the dielectric layer is arranged on the substrate and comprises a bottom surface close to the substrate, a top surface far away from the substrate, and two side faces connected with the bottom surface and the top surface; the top surface of the dielectric layer is longer than the bottom surface of the dielectric layer; the first metal layer is arranged on the dielectric layer; and the second metal layer is arranged on the substrate and is positioned on one side of the dielectric layer. Because the top surface of the dielectric layer is longer than the bottom surface of the dielectric layer, the transmission efficiency of TM light is improved, the leakage of TE light is suppressed and an extinction ratio of the grating polarizer is improved without reduction in the periods of the grating structures.

Description

technical field [0001] The invention relates to the technical field of polarizers, in particular to a grating polarizer. Background technique [0002] Polarizers, such as metal grating polarizers, are very important optical components in systems such as liquid crystal display, optical measurement, and optical communication, and have a very broad market. The metal grating polarizer has unique polarization performance, which is due to the different boundary conditions of the polarized light perpendicular to the grating vector (TM polarization) and parallel to the grating vector (TE polarization), and its equivalent refractive index is also different. Existing metal grating polarizers are mainly divided into single-layer and double-layer structures. In order to improve the transmission efficiency of TM light, generally speaking, the period of the metal grating is required to be less than 200nm. For the double-layer structure, at present, the method of evaporating metal at an a...

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Problems solved by technology

[0003] Due to the high requirements on the period of the metal grating at present, it is generally required to be below 200nm, which will make the preparation of the metal grating polarizer more difficult.

In addition, the metal protrusions of the existing metal grating have a rectangular structure, and it is very easy to block the opening when evaporating metal, thereby reducing the transmission efficiency and extinction ratio of TM light (that is, the transmission efficiency of TM light / the transmission efficiency of TE light )

Even if the method of evaporating metal at an angle is used, the transmission efficiency and extinction ratio of TM light cannot be effectively improved.

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