Modeling Of Graphene Devices Based On FDTD Method

As a kind of two dimensional nanomaterials, graphene is robustness and environment stability, as well as extraordinary optical proper-ties. Peculiar physical properties mean a lot of potential applications such as graphene battery, graphene antenna and graphene biological devices, etc. But limited to the preparation and testing technology, research and performance test of graphene devices is still a problem.In this research, we put forward two different kinds of Finite Difference Time Domain (FDTD) method for graphene devices simulation with vector fitting tools. These two methods are based on the equivalent dielectric constant and conductivity of graphene and coupled with Maxwell equation, respectively.First, we present a complex conjugate pole-residue pair model for representing the complex permittivity of graphene. We combine this model with FDTD method by auxiliary differential equation (ADE). Based on this method we design and simulate two kinds of graphene based photonic crystals in terahertz spectrum. The simulation result shows that the addition of graphene extends the photonic band gap of the photonic crystals and we can tune photonic band gap with changing the chemical potential of graphene. This is very different with the traditional photonic crystals.Secondly, order to solve the excessive consumption of computing resources caused by the simulation method based on complex conjugate pole-residue pair model. We propose three different kinds of graphene conductivity model (the constant surface conductivity model, the Drude model and the vector fitting model) which is used in different conditions and frequencies. The method treats the graphene as a special kind of electromagnetic field boundary and solves the clectromagnetic response of graphene devices by the surface current distribution on graphene which is acquired by FDTD method.Finally, this paper illustrates three different kinds of graphene application with the simulation method based on ohm law, the numerical results revealed different properties of graphene under different application scenarios, including absorption, plasmonic resonance and saturation gain. The numerical simulation results are validated through either microwave measurement or theoretical analysis.