THz quartz-enhanced photoacoustic sensor employing a quantum cascade laser source

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.

[1]  John Zweck,et al.  Theoretical analysis of a quartz-enhanced photoacoustic spectroscopy sensor , 2009 .

[2]  Lei Wang,et al.  Trace gas detection based on off-beam quartz enhanced photoacoustic spectroscopy: optimization and performance evaluation. , 2010, The Review of scientific instruments.

[3]  Vincenzo Spagnolo,et al.  Photoacoustic Techniques for Trace Gas Sensing Based on Semiconductor Laser Sources , 2009, Sensors.

[4]  E. Linfield,et al.  Terahertz quantum cascade lasers , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[5]  Alan Carrington,et al.  Rotational Spectroscopy of Diatomic Molecules , 2003 .

[6]  Masayoshi Tonouchi,et al.  Cutting-edge terahertz technology , 2007 .

[7]  David A. Ritchie,et al.  THz quantum cascade designs for optimized injection , 2008 .

[8]  G. Kitaeva.  Terahertz generation by means of optical lasers , 2008 .

[9]  H. Müller,et al.  Submillimeter, millimeter, and microwave spectral line catalog. , 1985, Applied optics.

[10]  Vincenzo Spagnolo,et al.  Modulation cancellation method for isotope 18O/16O ratio measurements in water. , 2012, Optics express.

[11]  A. Kosterev,et al.  Applications of quartz tuning forks in spectroscopic gas sensing , 2005 .

[12]  R. Tatam,et al.  Optical gas sensing: a review , 2012 .

[13]  James A. Harrington,et al.  Low-Loss Hollow Waveguide Fibers for Mid-Infrared Quantum Cascade Laser Sensing Applications , 2013, Sensors.

[14]  B. Fischer,et al.  Chemical recognition in terahertz time-domain spectroscopy and imaging , 2005 .

[15]  B. Williams.  Terahertz quantum cascade lasers , 2007, 2008 Asia Optical Fiber Communication & Optoelectronic Exposition & Conference.

[16]  H. Beere,et al.  Terahertz quartz enhanced photo-acoustic sensor , 2013 .

[17]  G. Scamarcio,et al.  Part-per-trillion level SF6 detection using a quartz enhanced photoacoustic spectroscopy-based sensor with single-mode fiber-coupled quantum cascade laser excitation. , 2012, Optics letters.

[18]  Simone Borri,et al.  A quartz enhanced photo-acoustic gas sensor based on a custom tuning fork and a terahertz quantum cascade laser. , 2014, The Analyst.

[19]  Kimberly L. Turner,et al.  Frequency dependent fluid damping of micro/nano flexural resonators: Experiment, model and analysis , 2007 .

[20]  A. Tredicucci,et al.  Tunable Emission in THz Quantum Cascade Lasers , 2011, IEEE Transactions on Terahertz Science and Technology.

[21]  Michael Christen,et al.  Air and gas damping of quartz tuning forks , 1983 .

[22]  Vincenzo Spagnolo,et al.  Ppb-level detection of nitric oxide using an external cavity quantum cascade laser based QEPAS sensor. , 2011, Optics express.

[23]  G. Scamarcio,et al.  Mid-infrared fiber-coupled QCL-QEPAS sensor , 2013 .

[24]  D Coquillat,et al.  Nanowire-based field effect transistors for terahertz detection and imaging systems , 2013, Nanotechnology.

[25]  Vincenzo Spagnolo,et al.  Coupling external cavity mid-IR quantum cascade lasers with low loss hollow metallic/dielectric waveguides , 2012 .

[26]  Lei Dong,et al.  QEPAS spectrophones: design, optimization, and performance , 2010 .

[27]  Frank K. Tittel,et al.  NO trace gas sensor based on quartz-enhanced photoacoustic spectroscopy and external cavity quantum cascade laser , 2010 .

[28]  Michael Watkinson,et al.  Terahertz spectroscopy: a powerful new tool for the chemical sciences? , 2012, Chemical Society reviews.

[29]  Qing Hu,et al.  High-power terahertz quantum cascade lasers , 2006, QELS 2006.