Study On Reflection Phased Array Of Terahertz Band Based On Electronically Controlled Liquid Crystal

A terahertz wave is an electrmagnetic wave with frequencies ranging from 0.1 to 10 THz and corresponding wavelengths ranging from 3 mm to 0.03 mm.Due to its unique advantages,terahertz has been valued in aerospace,communications,medicine and other fields.However,in recent years,the practical development of terahertz radar,communication and medical science has been slowly,especially the terahertz band phased array research has been in a stagnant state,which has restricted the development of many technologies.In this paper,the terahertz phased array is studied to solve the problems of complex fabrication and unreasonable size.As the dielectric constant of liquid crystal material changes under the influence of electromagnetic field,it is used as the regulating medium of the reflection phased array.This paper studies the physical mechanism of liquid crystal material and designs a reflection phased array based on electronically controlled liquid crystal by fully applying the characteristics of liquid crystal through analysis.First,a subunit of the reflective phased array is made,that is,a phase shifter.For the purpose of comparison,four different types of liquid crystals were filled in the subunit and tested using the terahertz time domain spectroscopy test system.It is true that the phase shift can be achieved by making a successful subunit,and the range of movement is related to the applied voltage and the type of liquid crystal material.According to the calculation,the phase movement of the subunit made of E7 liquid crystal material can reach 160 ° at most,which is the smallest among the four liquid crystals.The phase shift range of the subunit made of LDn liquid crystal material is the largest,and the maximum phase shift of 450 ° can be realized,which provides a reference for the selection of reflected phased array liquid crystal material.Then,the structure of the reflective phased array is designed.A mixture of 15 vol % dimethyl sulfoxide(DMSO)poly3,4-ethylene dioxythiophene: polystyrene sulfonate(PEDOT:PSS)was selected as the substrate transparent electrode,4×4 square array is set on the base,LDn liquid crystal material as the regulating medium,metal gold as the reflecting medium,the liquid crystal layer is 200 ?m thick.set parameters to simulate the structure,and the simulation results show that the structure can realize beam deflection,the deflection Angle is approximately 1 °.Finally,a series of processing methods are used to produce terahertz reflective phased array.By applying voltage to the substructure of each column on the array,the phased array can generate different phase shifts and construct a new equal-phase plane,so as to realize the deflection function of the beam.The optical path was designed for testing,and the test results showed that the reflected phased array could achieve 0.8 ° beam deflection,which was basically consistent with the simulation results.The reflective phased array designed and manufactured in this paper is small in size,light in weight,low in cost and simple in fabrication.