Absorption And Transmission Properties Of Graphene And Ionic-Crystal Metasurface

With the maturity of the mid-infrared source and detector technology and the2.5μm-25μm mid-infrared ultrashort pulse laser has unique advantages in the processing of semiconductor and polymer materials with special absorption characteristics in this band.The mid-infrared band is widely used in industrial,agricultural,information industry,military,medical,scientific research and other fields,such as molecular content identification,free space communication,infrared pump detection spectrum and remote sensing,etc.,making infrared wave devices also popular in the academic research community attention.In this paper,the theoretical method of linear transfer matrix and the method of COMSOL software simulation are used to design the tunable supersurface of metal graphene and the mid-infrared wave device of ionic crystal supersurface.The absorption,transmission characteristics and light field distribution are studied.The design and processing of future mid-infrared wave devices provide a feasible design solution.The main contents are as follows:1.Based on the tunable supersurface composed of graphene strip,metal layer and dielectric,a dielectric / graphene and metal pattern layer / dielectric electrically adjustable mid-infrared filter and narrow-band absorber were designed.The influence of various parameters on the transmittance and absorption was analyzed by using the characteristics of the metal dielectric function as a function of the frequency of the incident electromagnetic wave and the applied gate voltage to regulate the conductivity of the graphene strip.TM wave is incident on this supersurface,and the transmission spectrum corresponding to the change in the Fermi level of the graphene band is calculated,and then the absorption spectrum in the TE wave incident structure is studied,and then the electric field distribution characteristics of the graphene and metal pattern layer,and the application The effect of the voltage on the graphene strip on the electric field on the surface of the pattern layer.By changing the thickness of each structural layer,the size of the pattern layer,and the angle of incidence,the effects of various parameters on the transmittance,absorption,and locality of the electric field were studied.2.Based on the super surface of ion crystal and metal layer,a perfect absorber of ion crystal / metal pattern layer / dielectric / metal mid-infrared is designed.First,the transfer matrix method was used to calculate the absorption rates of the monolayer ionic crystals SiC,IM,DIM,IDM and GIDM supersurfaces,and the absorption peaks were calculated respectively.Then,the correctness of the transfer matrix results was verified by COMSOL software simulation.Two metal pattern layers(single half-ring and double half-ring)were designed to obtain two perfect absorbers with a narrow-band absorption rate of more than 99% in the mid-infrared.Compare with the absorptivity of the non-patterned layer,and analyze the effect of the materials and patterned layers on the absorption of the device.The parameters such as the thickness of the ion crystal and the angle of incidence were changed to optimize the absorption performance of the structure.Finally,a graphene layer is added to make the absorption metasurface into an electrically controllable absorber.