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Issue Eur. Phys. J. Appl. Phys. Volume 45, Number 2, February 2009 Article Number 21201 Number of page(s) 6 Section Instrumentation and Metrology DOI 10.1051/epjap:2008188 Published online 25 December 2008

Eur. Phys. J. Appl. Phys. 45, 21201 (2009)
DOI: 10.1051/epjap:2008188

Optoelectronic difference-frequency synthesiser: terahertz-waves for high-resolution spectroscopy

L. Aballea and L.F. Constantin

Laboratoire Phlam, UMR 8523 CNRS, 59655 Villeneuve d'Ascq, France

fconstan@lsh.univ-lille1.fr

Received: 31 August 2008 / Received in final form: 4 November 2008 / Accepted: 18 November 2008 / Published online: 25 December 2008

Abstract
We demonstrate a simple approach for a difference-frequency synthesiser within the terahertz domain. Two near-infrared CW diode lasers are frequency-locked to the resonances of a high finesse Fabry-Perot cavity using the Pound-Drever-Hall technique. Two acousto-optic modulators driven by RF synthesizers frequency-shift each diode laser and provide continuous tuning, modulation and switching capabilities for the difference-frequency. Terahertz-waves generated by heterodyne mixing in an ultrahigh-bandwidth photodetector are used to interrogate the rotational transitions in the ground state of the methyl-chloride.

PACS
42.62.Eh - Metrological applications; optical frequency synthesizers for precision spectroscopy.
33.80.-b - Photon interactions with molecules.
85.60.-q - Optoelectronic devices.
07.57.-c - Infrared, submillimeter wave, microwave and radiowave instruments and equipment.

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