Diode-pumped 214.8-nm Nd : YAG/Cr4+: YAG microchip laser system for the detection of NO

A passively Q-switched 214.8-nm Nd:YAG/Cr4+:YAG microchip laser system for the detection of NO was designed, constructed, and tested. The system uses the fifth harmonic of the 1.074-mu m transition in Nd:YAG to detect NO by l aser-induced fluorescence. A significant challenge was the development of a n environmentally stable coating to provide the necessary discrimination be tween the 1.074-mu m laser line and the stronger transition at 1.064 mu m. The exact position of the fifth-harmonic frequency was determined by use of NO fluorescence excitation spectra to be 46556 +/- 1.5 cm(-1). With a puls e energy of approximately 50 nJ of fifth-harmonic light, we observed a dete ction sensitivity for NO of approximately 15 parts per billion by volume in a simple, compact optical system. (C) 2000 Optical Society of America OCIS codes: 300.2530, 190.4160, 140.3530, 300.6360, 140.3580, 300.6540.