A Dual-mesh Framework for Multiphysics Simulation of Photoconductive Terahertz Devices

The operation of a photoconductive terahertz (THz) device relies on optoelectronic interactions and THz radiation. Although these two processes are coupled, in simulations, they are often modeled separately due to the large difference between the frequencies of optical and THz electromagnetic waves. To model both processes in a single simulation, we propose a dual-mesh discontinuous Galerkin (DG) scheme. Optoelectronic interactions and THz radiation are accounted for by solving, respectively, a coupled system of Maxwell and drift-diffusion equations discretized on a fine mesh and only the Maxwell equations discretized on a coarse mesh. This approach uses an efficient high-order interpolation scheme to “connect” electric field and current discretized on these two meshes. The proposed scheme is validated against experimental results.