Evanescent Wave Quartz-Enhanced Photoacoustic Spectroscopy Employing a Side-Polished Fiber for Methane Sensing

Authors

Cian F. Twomey, Centre for Advanced Photonics and Process Analysis, Munster Technological University, Cork, T12 P928, Ireland
Gabriele Biagi, Centre for Advanced Photonics and Process Analysis, Munster Technological University, Cork, T12 P928, Ireland; PolySense Lab, Dipartimento Interateneo di Fisica, University and Politecnico of Bari, Bari, CNR-IFN, Via Amendola 173, Bari 70126, ItalyFollow
Albert A. Ruth, School of Physics and Environmental Research Institute, University College Cork, Cork, Ireland
Marilena Giglio, PolySense Lab, Dipartimento Interateneo di Fisica, University and Politecnico of Bari, Bari, CNR-IFN, Via Amendola 173, Bari 70126, Italy
Vincenzo Spagnolo, PolySense Lab, Dipartimento Interateneo di Fisica, University and Politecnico of Bari, Bari, CNR-IFN, Via Amendola 173, Bari 70126, Italy
Liam O'Faolain, Centre for Advanced Photonics and Process Analysis, Munster Technological University, Cork, Ireland; Tyndall National Institute, Cork, IrelandFollow
Anton J. Walsh, Centre for Advanced Photonics and Process Analysis, Munster Technological University, Cork, T12 P928, IrelandFollow

ORCID

https://orcid.org/ 0000-0002-2978-6452

Document Type

Article

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Disciplines

Physical Sciences and Mathematics | Physics

Publication Details

Photoacoustics, vol. 36. © 2024 The Authors.

Abstract

We present an all-fiber-based laser gas analyzer (LGA) employing quartz-enhanced photoacoustic spectroscopy (QEPAS) and a side-polished fiber (SPF). The LGA comprises a custom quartz tuning fork (QTF) with 0.8 mm prong spacing, two acoustic micro-resonators (mR) located on either side of the prong spacing, and a single-mode fiber containing a 17 mm polished section passing through both mRs and QTF. The SPF polished face is positioned to enable the evanescent wave (EW) to create a photoacoustic wave and excite the fundamental flexural mode of the QTF. Sensor performance was demonstrated using methane in nitrogen gas mixtures, with CH4" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; word-spacing: normal; overflow-wrap: normal; text-wrap: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">4 mixing ratios ranging from 75 ppmv to 1% (by volume), measured with an accumulation time of 300 ms, and a minimum detection limit of 34 ppmv subsequently determined. The EW-QEPAS sensor is ideal for miniaturization, as it does not contain any free-space optics and is suitable for gas sensing in harsh environments and where mobility is required.

Recommended Citation

Cian F. Twomey, Gabriele Biagi, Albert A. Ruth, Marilena Giglio, Vincenzo Spagnolo, Liam O’Faolain, Anton J. Walsh, Evanescent wave quartz-enhanced photoacoustic spectroscopy employing a side-polished fiber for methane sensing, Photoacoustics, Volume 36, https://doi.org/10.1016/j.pacs.2024.100586.