Trace-gas detection based on the temperature-tuning periodically poled MgO: LiNbO 3 optical parametric oscillator

In this paper, the possibility of using the temperature-tuned optical parametric oscillator for trace gas detection was explored. A synchronization trace gas detection system was designed and demonstrated, in which the measuring errors caused by the instability of the OPO could be greatly reduced. The trace gas detection system was based on a periodically poled MgO-doped LiNbO3 optical parametric oscillator (OPO). The OPO was pumped by a diode-pumped passively Q-switched Nd:GdVO4 laser which produces 3-ns laser pulse. By changing the crystal temperature and the grating periods, the OPO could produce wavelength-tunable signal output. A computer was used to synchronously measure the signal wavelength, the signal power after passing the gas cell, and the power of the reference input which is used to calculate the signal power before passing the gas cell. The usefulness of the trace gas detection system for spectroscopy was demonstrated by directly measuring the photon absorption spectrum of the methane and acetylene gas cells.