Efficient Terahertz Generation Via GaAs Hybrid Ridge Waveguides

As a common semiconductor material with high performance in the terahertz band, GaAs is hardly employed in second-order nonlinear frequency conversion (NFC) directly due to its isotropy. Although thin waveguides can break the symmetry and induce birefringence for phase matching (PM), more research seems to be needed with GaAs-based structures. In this paper, a category of ridge waveguide is demonstrated with a hybrid structure composed of GaAs and SiN in different sizes. By using the difference frequency generation (DFG) technique with 2 μm and 10 μm pump lasers, simulations suggest that the hybrid waveguides are able to generate continuous-wave (CW) monochromatic terahertz waves from 1.59 THz to 2.66 THz. The output power reach 56.16 μW, corresponding to a conversion efficiency of 5.62 × 10
^-5
W
^-1
, which is much higher than that using bulk GaAs crystals. Such integrated hybrid waveguides have great potential in efficient on-chip terahertz systems.