Stable CW THz spectroscopy with PLC-LN hybrid phase modulator

We present a compact and stable continuous-wave terahertz spectroscopic system with a planar lightwave circuit-LiNbO 3 phase modulator for terahertz phase control. Thanks to significantly shortened optical paths with temperature control, the system enables fast vector measurement with effective phase stabilization. The phase stability of 2° was obtained over a period of 2 h.