Simulation Of Electromagnetic Characteristics Of Graphene Absorber In Terahertz Band

Graphene is a novel material with hexagonal carbon atoms,and its superior physical and chemical properties make it attract much attention and have been extensively studied.The emergence of graphene can help further improve the performance of these electronic devices.At this point,accurate numerical modeling and simulation of them have important engineering significance.The Finite Difference Time Domain(FDTD) method is a mature numerical algorithm.At present,the research on FDTD method mainly focuses on new solving methods,such as the unconditional stable alternating direction implicit format time domain finite difference(ADI-FDTD) method and hybrid implicit explicit time domain finite difference method(HIE-FDTD) with weak stability conditions.FDTD has limitations of Courant-Friedrich-Levy(CFL) stability conditions.In solving problems such as graphene simulation,since the mesh is more and more finely divided,the selection of the time step needs to be greatly reduced,and the increase in the number of time steps leads to a significant increase in the calculation time.This makes it impossible to apply FDTD to analyze graphene thin layers.The research in this paper is based on the HIE-FDTD method.The surface conductivity model of graphene is used to introduce current density through the auxiliary differential equation,which is effectively coupled into the HIE-FDTD method.First of all,the traditional FDTD method is introduced.including stability,numerical dispersion characteristics and boundary conditions.Secondly,the key theoretical problems in actual simulation are solved by deducing the formula of HIE-FDTD method in detail.The conductivity model of graphene is introduced.The conductivity of graphene is combined into the HIE-FDTD formula by ADE method.The iterative formula of the dispersion HIE-FDTD method reduces the complexity of the algorithm.In this method,the time step size is not limited by the size of the mesh in the graphene layer,which greatly improves the calculation efficiency.Finally,the dispersive HIE-FDTD method is applied to the graphene device in the terahertz band,which the graphene absorber is effectively simulated.The graphene electromagnetic response is obtained by changing the relevant parameters of the graphene structure.In the paper,the correctness and efficiency of the proposed algorithm are verified,which provides a theoretical basis for the simulation analysis of the device.