Numerical investigation of highly efficient and tunable terahertz-wave generation using a low-group-velocity and low-dispersion two-dimensional GaAs photonic crystal waveguide

Efficient terahertz (THz)-wave generation via difference frequency generation (DFG) in a GaAs-based two-dimensional photonic crystal waveguide (PhC-WG) was proposed and investigated through numerical simulations. A PhC-WG with a low-group-velocity and low-dispersion mode (LVLD PhC-WG) was designed, and THz–DFG spanning sub- to several THz in frequency was obtained. Electric field enhancement and phase-matching between two fundamental light pulses in the LVLD PhC-WG generated THz–DFG approximately 280 times that in a GaAs strip waveguide. This method is applicable to highly efficient and tunable small-footprint THz-emitting devices based on semiconductor materials.