Research On Terahertz Functional Devices Base On Graphene Metamaterials

Terahertz wave is the core technology of 6G communication,the new generation of medical imaging,etc.However,most natural materials all have very weak response to terahertz wave,there are seriously hampers detection and application of terahertz.Therefore,It will become an important link in the development of terahertz wave to design of various functional terahertz metamaterials devices.With the development of terahertz applications gradually diversified,tuning terahertz metamaterial functional devices have attracted extensive attention.However,all kind of the tuning methods have their own disadvantages and shortcomings,such as complex manufacturing process and poor tuning effect,which seriously restrict the practical application of tunable terahertz metamaterials.In order to solve these problems,three tunable terahertz metamaterial devices with different functions are designed by using the tuning method of electrostatic doped graphene.The main research contents of this paper are as follows:1.Construct a tunable absorber base on graphene terahertz metamaterial,the unit structure of the device is composed of two graphene disks,and the absorption spectrum of the device is freely tuned between single frequency,double frequency and wide frequency by electrostatic doping of graphene;On this basic,an equivalent circuit model was constructed to analyze the absorption principle of metamaterial and the tuning mechanism of graphene,and the tunning rationality was verified theoretically by calculating equivalent impedance.2.Design of a tunable electromagnetically induced transparent device base on graphene terahertz metamaterial,the unit structure of the device consists of a bimetal strip,an split resonant ring,and graphene integrated under the split resonant ring.The electromagnetic response of the bimetal strip is the bright mode,and the electromagnetic response of the split resonant ring is the subdark mode,perfect electromagnetic induced transparency(EIT)window is realized by two resonant couplings.At the same time,electrostatic doped graphene was used to control the coupling strength of its subdark mode,thus achieving the regulation of EIT window amplitude.In addition,a two-particle coupling model was built to explain the tuning mechanism of graphene,on the basis of which the slow light response and sensing performance of the device were studied.3.Propose a tunable ring dipole device base on graphene terahertz metamaterial,the unit structure of the device is composed of two axisymmetric double-opening resonant rings and graphene strips through the opening of the resonant ring.The free switching of metamaterial resonance mode from toroidal dipole to electric dipole or magnetic dipole was realized by using electrostatic doped graphene.By analyzing the distribution of surface current,electric field and magnetic field,the tuning mechanism of graphene was explained,and the multipole moment scattering model is used to verify the correctness of the designed structure.