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

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 coeff...

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Veröffentlicht in:Applied physics letters 2015-01, Vol.106 (2)
Hauptverfasser: Consolino, L., Campa, A., Ravaro, M., Mazzotti, D., Vitiello, M. S., Bartalini, S., De Natale, P.
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Sprache:eng
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Zusammenfassung: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 μW/mm2, for a gas pressure of 17 μbar, 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.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4905872