Optical field simulation of edge coupled terahertz quantum well photodetectors

By finite difference time domain (FDTD) simulation, we report on the optical field distribution within edge coupled terahertz quantum well photodetectors (THz QWPs) in detail. The coupling efficiency of THz QWP structures are studied from three aspects, including the electrode geometry, the position of the active region and the coupling angle. According to the simulation results, proper electrode geometry is suggested in different frequency region, and the optimal position of active region and coupling angle are presented. These results provide a useful guidance for the design and fabrication of the edge coupled THz QWP.