Mid-infrared difference-frequency generation in periodically poled KTiOAsO4 and application to gas sensing

Tunable mid-infrared radiation (3.45-3.75 mu m) with a power level of 0.14 mu W is generated by quasi-phase-matched difference-frequency mixing of a N d:YAG laser and a tunable-diode laser (near 1.5 mu m) in multigrating perio dically poled KTiOAsO4. The wavelength and temperature bandwidths are appro ximate to 65 nm cm and approximate to 62 degrees C cm, respectively. The te mperature-tuning slope of the phase-matched idler wavelength, -0.94 nm/degr ees C, is almost twice that of periodically poled KTiOPO4. We use the measu rements to derive a mid-infrared-corrected Sellmeier equation for the Z axi s of KTiOAsO4. The generated mid-infrared radiation is applied to sensitive high-resolution spectroscopy of the vs band of methane. (C) 2000 Optical S ociety of America.