Compact optical parametric oscillator based tunable mid-IR difference frequency laser spectrometer for intracavity photoacoustic trace gas sensing

Summary form only given. We have developed a nanosecond pulsed optical parametric oscillator (OPO) based difference frequency generation (DFG) photoacoustic (PA) spectrometer for sensitive trace gas monitoring. By mixing the residual fundamental of the Nd:YAG pump laser with the idler output of the commercial OPO (1.4-1.85 /spl mu/m) in bulk LiNbO/sub 3/ the wavelength range from 2.5-4.5 /spl mu/m is covered with considerable pulse energies. Absorption spectra of multicomponent mixtures consisting of up to seven gases at concentration levels in the lower ppm-range and with strongly interfering spectral characteristics have been recorded and analyzed.