High-resolution terahertz gain spectra of mid-infrared pumped NH3

Lampin, Jean-François

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https://hdl.handle.net/2142/100746 Copy

Description

Title

High-resolution terahertz gain spectra of mid-infrared pumped NH3

Author(s)

Lampin, Jean-François

Contributor(s)

• Postava, Kamil
• Vanwolleghem, Mathias
• Margulès, L.
• Motiyenko, R. A.
• Pienkina, A.
• Eliet, Sophie
• Micica, Martin

Issue Date

2018-06-20

Keyword(s)

Mini-symposium: Far-Infrared Spectroscopy

Abstract

Inversion of population in the terahertz (THz) range can be obtained thanks to the optical pumping of polar molecules in the mid-infrared range. Generally it is done with CO2 lasers but recently we have demonstrated the first molecular laser pumped by a quantum cascade laser (QCL). It is based on the optical pumping of the NH3 molecule in the ν2=1 state. The gain is obtained by the stimulated emission on pure inversion transitions of NH3 (large amplitude motions) around 1 THz that are not accessible to continuous-wave (CW) CO2 lasers. We present here CW high-resolution gain measurements of two strong lines: the (3,3) around 1.073 THz and the (4,4) around 1.083 THz. The measurements are done with a THz multiplication chain and an InSb bolometer. The gain profiles are recorded at different pressure and different QCL frequencies as for an IR/THz double resonance experiment. The highest gain at the best conditions are obtained with the (3,3) line: 10 dB/m for a pump power of about 40 mW. To our knowledge this gain is highest measured in the THz range for a CW-pumped molecule. These measurements will help the understanding and the design of our NH3 lasers. This kind of laser will find applications in THz molecular spectroscopy/astronomy as a source or as a local oscillator for heterodyne detection.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100746

DOI

10.15278/isms.2018.WI04

Copyright and License Information

Copyright 2018 Jean-François Lampin

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