Compact and tunable mid-infrared laser using QPM-LN waveguide and TLA

A compact and tunable difference frequency generation mid-infrared laser for gas sensing is developed using a quasi-phase-matched LiNbO 3 (QPM-LN) waveguide and a tunable laser diode array (TLA). The absorption spectra of methane from the -third- to -fifth-order around 3.3 mum are observed by tuning the QPM-LN waveguide temperature and the TLA wavelength. The absorption line width is investigated with high spectral resolution scanning and the result is compared with that calculated from the HITRAN database.