Sensitive multiplex spectroscopy in molecular fingerprint 2.4 um region with a Cr2+:ZnSe femtosecond laser
Journal article, Peer reviewed
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Original versionOptics Express 2007:1-6 10.1364/OE.15.016540
An ultrashort-pulse Cr2+:ZnSe laser is a novel broadband source for sensitive high resolution molecular spectroscopy. A 130-fs pulse allows covering of up to 380 cm-1 spectral domain around 2.4 µm which is analyzed simultaneously with a 0.12 cm-1 (3.6 GHz) resolution by a Fourier-transform spectrometer. Recorded in 13 s, from 70-cm length absorption around 4150 cm-1, acetylene and ammonia spectra exhibit a 3800 signal-to-noise ratio and a 2.4·10-7 cm-1·Hz-1/2 noise equivalent absorption coefficient at one second averaging per spectral element, suggesting a 0.2 ppbv detection level for HF molecule. With the widely practiced classical tungsten lamp source instead of the laser, identical spectra would have taken more than one hour.