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) |
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Format: | Artikel |
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. |
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ISSN: | 0003-6951 1077-3118 |
DOI: | 10.1063/1.4905872 |