Zheng, KaiyuanZheng, ChuantaoZheng, ChuantaoHu, LienGuan, GangyunMa, YanmingSong, FangZhang, YuZhang, YuWang, YidingTittel, Frank K.2021-07-302021-07-302021Zheng, Kaiyuan, Zheng, Chuantao, Zheng, Chuantao, et al.. "Light-induced off-axis cavity-enhanced thermoelastic spectroscopy in the near-infrared for trace gas sensing." <i>Optics Express,</i> 29, no. 15 (2021) Optical Society of Americ: 23213-23224. https://doi.org/10.1364/OE.430745.https://hdl.handle.net/1911/111046A 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 ∼12000 in atmospheric pressure) and a 10cm-long Fabry-Perot cavity (finesse ∼ 482). By probing a H2O line at 7306.75 cm-1, the developed OA-CETES sensor achieved a minimum detection limit (MDL) of 8.7 parts per million (ppm) for a 300 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.engPublished under the terms of the OSA Open Access Publishing AgreementJournal articleoe-29-15-23213https://doi.org/10.1364/OE.430745