Observation of THz to near-Infrared parametric conversion in ZnGeP(2) crystal

We observed a THz parametric conversion in which a near-infrared laser beam was mixing with a THz wave to generate a radiation in the near-infrared region (i.e. an upconverted signal) through difference-frequency generation phase-matched in a ZnGeP(2) crystal. By measuring the upconverted signal, we deduced the characteristics of the THz pulses participating in the frequency mixing. Specifically, we determined the range of the incident wavelengths, the minimum detectable energy per pulse, and the average linewidth of the THz pulses as 91-139 microm, 276 pJ, and 0.36 cm(-1), respectively.