A terahertz photonic crystal wavelength division multiplexer based on graphene surface plasmon polaritons

This paper presents a two-dimensional (2D) photonic crystal structure based on graphene surface plasmon polaritons (SPP) for terahertz wavelength division multiplexing (WDM) applications. By etching a periodic array of equal-diameter cylindrical holes with the same height in the ground, a periodic SPP effective index profile of 2D photonic crystal can be created on graphene with a single gate voltage between graphene and ground. Based on this uneven ground structure, a photonic crystal multimode interference (MMI) WDM has been demonstrated. Simulation results show that the designed device exhibits isolations of higher than 17.30 dB and bandwidth of 0.06 THz at both frequencies.