Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser

Year: 2015

Authors: Consolino L., Campa A., Ravaro M., Mazzotti D., Vitiello M. S., Bartalini S., De Natale P.

Autors Affiliation: Istituto Nazionale di Ottica (INO) – CNR, Largo E. Fermi 6, Firenze 50125, Italy;
European Laboratory for Non-Linear Spectroscopy (LENS), Via N. Carrara 1, Sesto Fiorentino 50019, Italy
NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, Italy

Abstract: We report on the evidence of saturation effects in a rotational transition of CH3OH around 2.5 THz, induced by a free-running continuous-wave quantum cascade laser (QCL). The QCL emission is used for direct-absorption spectroscopy experiments, allowing to study the dependence of the absorption coefficient on gas pressure and laser intensity. A saturation intensity of 25 mu W/mm(2), for a gas pressure of 17 mu bar, is measured. This result represents the initial step towards the implementation of a QCL-based high-resolution sub-Doppler THz spectroscopy, which is expected to improve by orders of magnitude the precision of THz spectrometers. (C) 2015 AIP Publishing LLC.


Volume: 106      Pages from: 021108-1  to: 021108-4

More Information: This work was partly supported by the Italian Ministry of Education, University, and Research (MIUR) through the program FIRB-Futuro in Ricerca 2010, RBFR10LULP; Laserlab-Europe, Grant Agreement No, 284464, EU 7th Framework Program; ESFRI Roadmap, Extreme Light Infrastructure (ELI) project.
KeyWords: Absorption spectroscopy; Quantum cascade lasers; Semiconductor lasers; Spectrometers; Terahertz waves, Absorption co-efficient; Direct absorption spectroscopies; Molecular transitions; Orders of magnitude; Rotational transition; Saturated absorptions; Saturation effects; Saturation intensity, Terahertz spectroscopy
DOI: 10.1063/1.4905872

Citations: 18
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