Frequency-tunable high-power terahertz wave generation from GaP

A frequency-tunable terahertz wave was generated from GaP crystals using an optical parametric oscillator as the pump source and a YAG laser (1.064 μm) as the signal source. By tuning the very small angle, ${\theta }_{\mathrm{in}},$ between the pump and signal light beam directions, tunable terahertz waves over the frequency range from 0.5 to 3 THz were obtained. The THz frequency changed almost linearly with the angle ${\theta }_{\mathrm{in}}.$ The precise noncollinear phase matching condition is discussed. The pulsed peak power of the THz wave was as high as 480 mW at 1.3 THz.