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 singlemode 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 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.

Evanescent wave quartz-enhanced photoacoustic spectroscopy employing a side-polished fiber for methane sensing / Twomey, Cian F.; Biagi, Gabriele; Ruth, Albert A.; Giglio, Marilena; Spagnolo, Vincenzo; O’Faolain, Liam; Walsh, Anton J.. - In: PHOTOACOUSTICS. - ISSN 2213-5979. - ELETTRONICO. - 36:(2024). [10.1016/j.pacs.2024.100586]

Evanescent wave quartz-enhanced photoacoustic spectroscopy employing a side-polished fiber for methane sensing

Giglio, Marilena;Spagnolo, Vincenzo;
2024-01-01

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 singlemode 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 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.
2024
Evanescent wave quartz-enhanced photoacoustic spectroscopy employing a side-polished fiber for methane sensing / Twomey, Cian F.; Biagi, Gabriele; Ruth, Albert A.; Giglio, Marilena; Spagnolo, Vincenzo; O’Faolain, Liam; Walsh, Anton J.. - In: PHOTOACOUSTICS. - ISSN 2213-5979. - ELETTRONICO. - 36:(2024). [10.1016/j.pacs.2024.100586]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/265862
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