We report on an innovative quartz enhanced photoacoustic (QEPAS) gas sensor operating in the THz spectral range, employing a custom quartz tuning fork (QTF) with the two prongs spaced by ~800 μm. To test our sensor we employed a quantum cascade laser light source and selected a methanol rotational absorption line falling at 131.054 cm^-1 (~3.93 THz), with line-strength S = 4.28•10^-21 cm. The sensor operated at 10 Torr pressure on the QTF first flexion resonance frequency at 4245 Hz. We achieved a QEPAS normalized noise-equivalent absorption of 2•10^-10 W·cm^-1•Hz^-1/2 comparable with the best result of mid-IR QEPAS systems.

Date Published: 31 January 2014
PDF: 11 pages
Proc. SPIE 8993, Quantum Sensing and Nanophotonic Devices XI, 899320 (31 January 2014); doi: 10.1117/12.2033620

Published in SPIE Proceedings Vol. 8993:
Quantum Sensing and Nanophotonic Devices XI
Manijeh Razeghi; Eric Tournié; Gail J. Brown, Editor(s)