A study on a novel tuning method of ring-cavity THz-wave parametric oscillator

摘要

We demonstrate a widely tunable terahertz (THz)-wave parametric oscillator (TPO) in a ring cavity configuration using a novel frequecy-tuning method that rotates a single mirror forming the cavity. The TPO consists of a MgO:LiNbO{sub}3 crystal as a nonlinear optical crystal in a three-mirror ring cavity. We obtain the continuous tuning of THz-wave frequency in the 0.93 to 2.7 THz range by rotating the mirror. Maximum THz-wave output of 69.6pJ/pulse at 1.3 THz is coupled out from a single Si prism coupler due to the optimum arrangement of the nonlinear crystal. We also apply the ring-cavity TPO to THz Spectroscopic system and THz-wave spectroscopy of HCl gas is measured in order to check the tuning controllability. The high performance of the TPO is confirmed from the transmission dip of the measured spectrum in agreement with the known center absorption lines.