Dielectric metasurface collimating lens matched with terahertz photoconductive antenna in use

Abstract

The invention relates to a terahertz waveband dielectric metamaterial, and aims to design and produce a device with a small size, easy integration and higher transmission efficiency for improving the flexibility of a photoconductive antenna-based terahertz time-domain spectral system, so as to replace a silicon lens and a paraboloidal mirror or a silicon lens and a terahertz lens. A technical scheme is adopted as follows: a dielectric metasurface collimating lens matched with a terahertz photoconductive antenna in use consists of two parts: a substrate layer and a two-dimensional microstructure layer, wherein the substrate layer is an isotropous high-resistance silicon layer with uniform thickness; the substrate layer is used for providing mechanical support for the two-dimensional microstructure layer, and the two-dimensional microstructure layer is also made from high-resistance silicon; the two-dimensional microstructure layer is formed by tetragonal lattices of cylindrical structures in arrangement similar to a concentric annulus way; and the cylindrical structures of different diameters have different modulation depths on phases, and the cylindrical structures on the same ring of the concentric annulus are the same in diameters. The dielectric metasurface collimating lens is mainly applied to design and manufacturing of the device with higher transmission efficiency.

Description

technical field [0001] The invention relates to a dielectric metamaterial in the terahertz band, which can be used in a terahertz system with a planar photoconductive antenna emission source instead of a traditional super-hemispheric high-resistance silicon lens to realize the collimation of terahertz waves. Specifically, it involves a dielectric metasurface collimating lens used in conjunction with a terahertz photoconductive antenna. Background technique [0002] In recent years, terahertz technology has become a research hotspot in the fields of electromagnetics and spectroscopy. Terahertz science and technology integrates the characteristics of electronics and photonics, involving physics, chemistry, optics, material science, microwave and millimeter wave electronics and other disciplines, and is a typical interdisciplinary frontier discipline. Compared with infrared waves, terahertz waves have less scattering and stronger penetrating power. Compared with microwaves, te...

AI Technical Summary

Problems solved by technology

The terahertz wave passes through the super-hemispheric high-resistance silicon lens and finally diverges at a cone angle of 34° [4] , the parabolic mirror or terahertz lens is needed to converge the terahertz wave again in order to collimate the terahertz wave into a plane wave. Since the parabolic mirror and terahertz lens occupy a certain amount of space, this will not be conducive to the realization of a small terahertz system. change

Usually, the hyperhemispherical high-resistance silicon lens used in the terahertz time-domain spectroscopy system has a diameter of about 1 cm. Due to the spherical shape of the hyperhemispherical silicon lens, it cannot be directly grown on the antenna by photolithography. Antenna alignment and installation issues

The more important problem is that the refractive index of silicon is too large, and the reflection loss of terahertz waves is serious at the silicon-air interface

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