Difference–frequency infrared generation and application to the water vapor trace monitoring

Abstract

Based on nonlinear optical frequency mixing of two optical lasers in an 1-mm thick AgGaS 2 crystal plate, continuous-wave infrared radiation has been generated from 1540 to 2170 cm −1. Use of the thin crystal plate permits extension of the generated infrared spectral coverage by a phase-matching technique of angle tuning associated with wavelength tuning. Spectroscopic detection of water vapor trace in air has been performed. A new synthetic baseline model has been developed in the present work to extract the spectral signals from a baseline structure due to phase-mismatching and etalon effects.