Study of Tunable Terahertz-Wave Generation in Isotropic Semiconductor Crystals Based on Dual-Wavelength KTP-OPO Operating near Degenerate Point

Continuously tunable coherent terahertz-wave generation from 0.1 to 2.7 THz can be achieved in isotropic semiconductor nonlinear crystals by difference frequency mixing. We experimentally demonstrated a high-power, narrow-linewidth, angle-tuned pulsed dual-wavelength KTP-OPO operating near the degenerate point, which was used as the pump source for terahertz-wave generation. We theoretically studied the feasibility of the cross-Reststrahlen band dispersion compensation phase matching in the collinear optical mixing technique in this process. A theoretical analysis of perfect phase-matching conditions and coherence length for the ZnTe crystal was presented, according to its optical dispersion property.