Real-time Detection of Terahertz wave from Quantum Cascade Laser by Frequency Up-conversion in a Nonlinear Crystal

Terahertz wave is expected to be used in such wireless communication systems due to its potentially broad bandwidth. In this presentation, we report on the detection of terahertz radiations from terahertz quantum cascade lasers (THz-QCLs) by up-conversion using the intense near-infrared with MgO:LiNbO
₃
crystal as a nonlinear crystal. The intense near-infrared beam is generated from the microchip Nd:YAG laser based MOPA system. The up-converted signal was observed when the injection of the pulse current and the optical pulse pumping occurred at the same time. From these results, it is shown that the frequency up-conversion technique is useful to investigate the lasing dynamics of THz-QCLs.