Research And Design Of Terahertz Metamaterials Based On Graphene

In recent years,terahertz metamaterials have a wide range of applications in the fields of optical communication,biomedicine,and high-precision imaging.However,most of the terahertz materials at home and abroad have the disadvantages of low performance,complex structure and non-tunability.In this paper,the new two-dimensional graphene is used instead of precious metal.The physical mechanism of graphene metamaterials is studied,and the high performance and structure are designed.Simple,tunable terahertz metamaterial.The main research work of this thesis is as follows:(1)A graphene-based adjustable broadband terahertz absorber is designed.In this paper,an ultra-wide terahertz absorber with a bandwidth of 4.8 THz is realized by dynamic regulation of the surface plasmon effect of graphene.The average absorption rate of the absorber in the wide frequency range of 3-7.8 THz is 96.7%.The absorber structure is relatively simple and does not rely on complex patterned graphene.In addition,the absorber has flexible adjustability.In this working frequency band,the dynamic adjustment of the graphene Fermi level by the applied voltage can realize the switching effect in the working band:the open state(absorption rate>90)%)to the off state(reflectance>90%).(2)A tunable electromagnetically induced transparent device based on multilayer graphene was designed.The coupling effect between graphene produces a transparent transmission window.By the dynamic tuning of the graphene Fermi level by the applied voltage,the transparent window can be modulated at different depths,and the switching effect and electromagnetic-like of the transparent window can be realized at a specific frequency.Inducing transparency effects(EIT).In addition,the structure can achieve a slow light regulation effect in the terahertz band with a positive delay of up to 0.9 ps.The above graphene-based metamaterial has simple structure,superior performance and strong adjustability,and has great potential application value in terahertz devices.