Light-induced off-axis cavity-enhanced thermoelastic spectroscopy in the near-infrared for trace gas sensing.
Opt Express
; 29(15): 23213-23224, 2021 Jul 19.
Article
em En
| MEDLINE
| ID: mdl-34614589
ABSTRACT
A trace gas sensing technique of light-induced off-axis cavity-enhanced thermoelastic spectroscopy (OA-CETES) in the near-infrared was demonstrated by combing a high-finesse off-axis integrated cavity and a high Q-factor resonant quartz tuning fork (QTF). Sensor parameters of the cavity and QTF were optimized numerically and experimentally. As a proof-of-principle, we employed the OA-CETES for water vapor (H2O) detection using a QTF (Q-factor â¼12000 in atmospheric pressure) and a 10cm-long Fabry-Perot cavity (finesse â¼ 482). By probing a H2O line at 7306.75â
cm-1, the developed OA-CETES sensor achieved a minimum detection limit (MDL) of 8.7 parts per million (ppm) for a 300â
ms integration time and a normalized noise equivalent absorption (NNEA) coefficient of 4.12 × 10-9cm-1 WHz-1/2. Continuous monitoring of indoor and outdoor atmospheric H2O concentration levels was performed for verifying the sensing applicability. The realization of the proposed OA-CETES technique with compact QTF and long effective path cavity allows a class of optical sensors with low cost, high sensitivity and potential for long-distance and multi-point sensing.
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MEDLINE
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En
Ano de publicação:
2021
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Article