Optical detection of molecular species at sub-ppt concentration levels

Year: 2011

Authors: Mazzotti D., Bartalini S., Borri S., Cancio P., Galli I., Giusfredi G., De Natale P.

Autors Affiliation: Istituto Nazionale di Ottica (INO) – CNR
European Laboratory for Non-linear Spectroscopy (LENS)

Abstract: The fundamental (and strongest) ro-vibrational transitions of atmospheric molecules lie in the mid-IR region of the spectrum (the so-called molecular fingerprint region). Since trace-gas detection sensitivity scales inversely with line-strength, mid-IR is the best suited spectral region to perform high-sensitivity molecular spectroscopy. With this motivation, we have designed and realized a difference-frequency-generated coherent source, with 3850-4540 nm tuning range and TEM00 spatial mode [1]. Phase locking of the near-IR pump laser to the signal one involved in the non-linear mixing process, through a Ti:sapphire-based optical frequency comb, also gives the generated idler radiation narrow linewidth and Cs-standard traceability [2]. The relatively high power of this source (30 mW at 4510 nm), greatly enhanced by a high-finesse Fabry-Perot cavity (F 11000), enables saturation spectroscopy at pressures even higher than 10 mbar. © 2011 IEEE.

Conference title: 2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference, CLEO EUROPE/EQEC 2011
Place: Munich; Germany; 22-26 May 2011

KeyWords: Atmospheric molecules; Coherent sources; Fabry-Perot cavity; High-power; High-sensitivity; Mixing process; Molecular fingerprint; Molecular species; Narrow-line width; Near-IR; Non-linear; Optical detection; Optical frequency combs; Phase-locking; Pump laser; Saturation spectroscopy; Spatial modes; Spectral region; Sub-ppt concentrations; Ti:sapphire; Trace gas detection; Tuning ranges, Cesium; Fabry-Perot interferometers; Molecular spectroscopy; Optics; Pumping (laser); Quantum electronics, Electron optics
DOI: 10.1109/CLEOE.2011.5943069