Research On Adjustable Terahertz Metamaterial Absorber

Terahertz wave between microwave and infrared waves has many excellent characteristics.As the metamaterial with extraordinary electromagnetic characteristics,it has always been a research hotspot for researchers and its related research fields have received broad attention.By combining graphene with the metamaterial,this paper studies the metamaterial absorber with adjustable absorptivity in terahertz band,and analyzes as with as discusses the electromagnetic characteristics of graphene and relevant theories.Meantime,the research status and application of terahertz wave THz metamaterial absorbers are briefly introduced,and the electromagnetic properties of graphene are described and discussed in detail.This paper also analyzes three kinds of equivalent medium theory,impedance matching theory and multiple interference theory of metamaterial absorbers.Based on the research progress and theoretical basis,two different types of THz metamaterial absorbers were designed:Firstly,the quintuple-band terahertz metamaterial absorber loaded with graphene is proposed.The simulation results show that at 0.93 THz,1.72 THz,2.39 THz,3.05 THz and 3.72 THz,the absorption peak reaches a high level and the polarization insensitive and wide incident angle characteristics are maintained.The change of absorptivity has been compared and simulated under different thickness of medium layer and different structure of graphene.And the absorption mechanism of the absorbent is further analyzed by using the electric field energy distribution diagram.Based on the properties that the chemical potential of graphene can be regulated,the absorbency of the absorbent can be dynamically adjusted.Secondly,the wideband terahertz metamaterial absorber loaded with graphene is also proposed.Through the form arranged by a combination of rings and disks,the absorption rate can reach over 90%and the relative bandwidth can reach 81.44%in the frequency band from 1.15 THz to 2.73 THz.Similarly,the absorber has the functions of insensitive polarization,wide incident angle and adjustment.Based on the equivalent impedance theory,the metamaterial and free space impedance match well.The absorption mechanism of electromagnetic wave is explained by the energy distribution of surface current and electric field.Through the change of the graphene chemical potential,the absorption rate is dynamically adjusted from 0 to 100%.The metamaterial absorber loaded with graphene can not only realize the multi-frequency and wideband absorption characteristics,but also can realize the dynamic adjustable absorption performance.Therefore,it has certain application value in the design of adjustable devices.