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

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.

Disciplines

Physical Sciences and Mathematics | Physics

DOI

10.1016/j.pacs.2024.100586

Publication Details

Photoacoustics, vol. 36. © 2024 The Authors.

Publisher

Elsevier

License Condition

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

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.