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Title: 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 CH{sub 3}OH 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/mm{sup 2}, 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.
Authors:
; ; ; ; ;  [1] ;  [2] ;  [3]
  1. INO, Istituto Nazionale di Ottica-CNR, Largo E. Fermi 6, Firenze I-50125 (Italy)
  2. (Italy)
  3. NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa I-56127 (Italy)
Publication Date:
OSTI Identifier:
22399079
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ABSORPTION SPECTROSCOPY; ACCURACY; DOPPLER EFFECT; EMISSION; IMPLEMENTATION; LASERS; METHANOL; RESOLUTION; SATURATION