Terahertz-wave detection in a GaP-based hybrid waveguide using a nonlinear optical parametric process

We design and simulate a GaP-based hybrid waveguide structure for room temperature terahertz-wave detection by using a nonlinear optical parametric process that is based on the photonic conversion from terahertz to the optical domain. The waveguide structure consists of a GaP rib waveguide for optical pump light, and an Si waveguide for the terahertz wave can provide the conversion from terahertz to the optical frequency domain. Owing to the strong confinement of the terahertz wave into the waveguide, high conversion efficiency of 0.05 W^-1 (detection at 4.7 THz) can be achieved. The noise equivalent power for terahertz-wave detection by using an optical single photon detector is estimated to be 12 fW/Hz^1/2, which is higher than that obtained using a commercially available 4.2 K Si bolometer.