We present a novel compact pulsed laser spectrometer based on difference-frequency mixing of a cw tunable external-cavity diode laser (795–825 nm) and a pulsed Nd:YAG laser (1064 nm) in bulk LiNbO3 . The pulsed mid-IR source is continuously tunable from 3.16 to 3.67µm and exhibits a linewidth of only 154 MHz, a peak power of ≈50µW , and a pulse duration of 6 ns at a 6.5-kHz repetition rate. Spectra of methane in room air and formaldehyde have been recorded at room-temperature operation in a multipass cell with deduced detection limits of 10 and 40 parts in 109 , respectively.
© 1999 Optical Society of America
Michael Seiter and Markus W. Sigrist, "Compact gas sensor using a pulsed difference-frequency laser spectrometer," Opt. Lett. 24, 110-112 (1999)