Study On Terahertz Absorber Based On Graphene Tunable

In recent years,terahertz tunable absorber has become a research hotspot.However,the previous study of absorber band is usually fixed frequency point,its absorption rate is difficult to be tuned flexibly,and the appearance of graphene breaks the traditional metal-medium-metal absorber,by constructing graphene-dielectric-metal absorber,the absorption rate of graphene-dielectric-metal absorber is difficult to be tuned flexibly,and graphene-dielectric-metal absorber is constructed.The absorption rate of the absorber can be tuned by changing the characteristic of graphene by the applied voltage,and then the terahertz wave can be flexibly controlled.Based on the adjustable properties of graphene,two kinds of narrow band graphene tunable terahertz absorbers and two broadband tunable terahertz absorbers have been designed in this paper.1.A graphene dual frequency tunable terahertz absorber is proposed,which consists of bottom metal,intermediate medium and top graphene layer.The top graphene layer is composed of a cross structure and a center symmetric defect ring.When the chemical potential of graphene is?_c=0.7eV,the absorptivity of the designed absorber in 0.512THz and 1.461THz can reach 0.986 and 0.98 respectively.According to the analysis,the proposed dual-frequency absorber satisfies the plasma hybrid model.The absorption mechanism of dual-frequency absorber is analyzed by electric field and magnetic field distribution diagram.2.A triple-frequency tunable terahertz absorber for graphene is proposed.When the chemical potential of graphene is 0.8eV,the three-frequency point can be perfectly absorbed by the interaction of electric resonance and magnetic resonance.The absorption mechanism of the proposed absorber is explained by the equivalent circuit model,and the influence of changing the single structure parameter on the absorption performance of the absorber is further simulated and analyzed.However,due to the insensitive polarization of the designed absorber,the stability of the absorptivity over 80%can be maintained in the range of 0°~60°of the incident angle under the polarization wave of TE,TM.3.An omega-type graphene terahertz broadband absorber is designed.When the?_c=0.5eV of graphene is changed,the absorptivity of the absorber can reach 99%in the 1.36THz~1.54THz frequency range and 99%in the 1.05~1.69THz frequency range.The absorptivity of the absorber can reach more than 90%.The absorption mechanism is investigated by using the electric field distribution in the TE and TM modes.In addition,the calculation results show that due to the particularity of graphene,the absorber can exhibit a narrow band absorption and a broadband absorption under different relaxation time of graphene.In addition,the sensitivity of the absorptivity of the designed absorber to the incident angle is also discussed in the TE,TM mode,and the polarization of TE and TM remains good absorption and bandwidth characteristics in the range of 0°~60°.4.A complementary symmetrical petal broadband graphene terahertz absorber was constructed by using the hollowed complementary symmetric pattern fossil indolene layer,and the absorption mechanism was analyzed by using the electric field distribution map.At the same time,the variation of the parameters affecting the absorber is discussed in detail.When the chemical potential of graphene is adjusted from 0.1eV to 0.7eV,the simulation results show that the absorptivity of the proposed absorber can be increased from less than 5%to more than 80%in the frequency range of 2.66THz-3.46THz.The absorption bandwidth of the absorber is0.8 THz,in which the absorptivity of 2.92THz and 3.35THz is as high as 95%and97%,respectively.Due to the high symmetry of the structure,the absorber has excellent polarization insensitivity in the range of 0°~50°.