High resolution ZrF₄-fiber-delivered multi-species infrared spectroscopy

Using coherent broadband mid-infrared light from a picosecond optical parametric oscillator we introduce a flexible, easy to use, high-resolution technique which can be utilized to conduct remote stand-off, or fiber delivered, multi-species spectroscopy in a spectroscopically cluttered environment. In particular, both narrow line-like and broad continuum-like species can be handled simultaneously. If only species with narrow line-like absorptions are present, this can be done without the need for an explicit reference spectrum. We demonstrate the approach by performing absorption spectroscopy of H₂O, CH₄, CH₃OH and C₂H₇NO (MEA) at high optical resolution (≈0.033 cm⁻¹) and via fiber delivery, opening the possibility of conducting multi-species spectroscopy in remote and hazardous environments. Spectral co-fitting of all absorption features and of the spectrum of the light-source provides a robust means of determining species concentrations, with detection limits of 290 ppb and 890 ppb obtained for CH₄ and MEA respectively using a 10.5-m Herriott cell and 32 seconds measurement time.