Browsing by Author "Zheng, Kaiyuan"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Light-induced off-axis cavity-enhanced thermoelastic spectroscopy in the near-infrared for trace gas sensing(Optical Society of Americ, 2021) Zheng, Kaiyuan; Zheng, Chuantao; Zheng, Chuantao; Hu, Lien; Guan, Gangyun; Ma, Yanming; Song, Fang; Zhang, Yu; Zhang, Yu; Wang, Yiding; Tittel, Frank K.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 ∼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.Item Long-distance in-situ methane detection using near-infrared light-induced thermo-elastic spectroscopy(Elsevier, 2021) Hu, Lien; Zheng, Chuantao; Zhang, Minghui; Zheng, Kaiyuan; Zheng, Jie; Song, Zhanwei; Li, Xiuying; Zhang, Yu; Wang, Yiding; Tittel, Frank K.A wavelength-locked light-induced thermo-elastic spectroscopy (WL-LITES) gas sensor system was proposed for long-distance in-situ methane (CH4) detection using a fiber-coupled sensing probe. The wavelength-locked scheme was used to speed the sensor response without scanning the laser wavelength across the CH4 absorption line. A small-size piezoelectric quartz tuning fork (QTF) with a wide spectral response range was adopted to enhance the photo-thermal signal. The optical excitation parameters of the QTF were optimized based on experiment and simulation for improving the signal-to-noise ratio of the LITES technique. An Allan deviation analysis was employed to evaluate the limit of detection of the proposed sensor system. With a 0.3 s lock-in integration time and a ∼ 100 m optical fiber, the WL-LITES gas sensor system demonstrates a minimum detection limit (MDL) of ∼ 11 ppm in volume (ppmv) for CH4 detection, and the MDL can be further reduced to ∼ 1 ppmv with an averaging time of ∼ 35 s. A real-time in-situ monitoring of CH4 leakage reveals that the proposed sensor system can realize a fast response (< 12 s) for field application.Item Near-infrared acetylene sensor system using off-axis integrated-cavity output spectroscopy and two measurement schemes(Optical Society of America, 2018) Zheng, Kaiyuan; Zheng, Chuantao; He, Qixin; Yao, Dan; Hu, Lien; Zhang, Yu; Wang, Yiding; Tittel, Frank K.For highly sensitive and accurate acetylene (C2H2) detection, a near-infrared (NIR) off-axis integrated-cavity output spectroscopy (OA-ICOS) sensor system based on an ultra-compact cage-based absorption cell was proposed. The absorption cell with dimensions of 10 cm × 8 cm × 6 cm realized a dense-pattern and an easily-aligned stable optical system. The OA-ICOS sensor system employed a 6cm-long optical cavity that was formed by two mirrors with a reflectivity of 99.35% and provided an effective absorption path length of ∼9.28 m. The performance of the C2H2 sensor system based on two measurement schemes, i.e. laser direct absorption spectroscopy (LDAS) and wavelength modulation spectroscopy (WMS) is reported. A NIR distributed feedback (DFB) laser was employed for targeting a C2H2 absorption line at 6523.88 cm−1. An Allan deviation analysis yielded a detection sensitivity of 760 parts-per-billion in volume (ppbv) for an averaging time of 304 s using the LDAS-based OA-ICOS. A detection sensitivity of 85 ppbv for an averaging time of 250 s was obtained using the WMS-based OA-ICOS, which was further improved by a factor of ~9 compared to the result obtained with the LDAS method. The proposed sensor system has the advantages of reduced size and cost with acceptable detection sensitivity, which is suitable for applications in trace gas sensing in harsh environments and weight-limited balloon-embedded observations.Item Near-Infrared Dual-Gas Sensor System for Methane and Ethane Detection Using a Compact Multipass Cell(Frontiers Media S.A., 2022) Xi, Zhenhai; Zheng, Kaiyuan; Zheng, Chuantao; Zhang, Haipeng; Song, Fang; Li, Chunguang; Ye, Weilin; Zhang, Yu; Wang, Yiding; Tittel, Frank K.In this invited paper, a compact dense-pattern multipass cell-based near-infrared sensor system was demonstrated for detection of parts-per-billion in volume (ppbv)-level methane (CH4) and ethane (C2H6). The dimension size of the fabricated gas cell is 18.5 × 8 × 9 cm3 with an absorption path length of 9.39 m. CH4 measurement was realized within a spectral range of 6,046–6,048 cm−1 and an absorption line of 6,046.95 cm−1. The spectral range for C2H6 detection is 5,951–5,953 cm−1 with an absorption line of 5,951.73 cm−1. Allan deviation analysis was used for evaluating the dual-gas sensing performance, and a detection limit of 78 ppbv for CH4 and 190 ppbv for C2H6 were achieved, respectively, with an averaging time of 0.8 s. Furthermore, CH4 measurement in the indoor and outdoor atmosphere was both performed to verify the field sensing capability of the sensor system. Compared with two separate sensor systems for CH4/C2H6 sensing, the proposed dual-gas sensor system using two near-infrared lasers and one multipass cell has the advantages of low-cost, compact-size without decreasing the selectivity and sensitivity.Item Review of Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (IBBCEAS) for Gas Sensing(MDPI, 2018) Zheng, Kaiyuan; Zheng, Chuantao; Zhang, Yu; Wang, Yiding; Tittel, Frank K.Incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) is of importance for gas detection in environmental monitoring. This review summarizes the unique properties, development and recent progress of the IBBCEAS technique. Principle of IBBCEAS for gas sensing is described, and the development of IBBCEAS from the perspective of system structure is elaborated, including light source, cavity and detection scheme. Performances of the reported IBBCEAS sensor system in laboratory and field measurements are reported. Potential applications of this technique are discussed.Item Slow-light-enhanced on-chip 1D and 2D photonic crystal waveguide gas sensing in near-IR with an ultrahigh interaction factor(Optica Publishing Group, 2023) Peng, Zihang; Huang, Yijun; Zheng, Kaiyuan; Zheng, Chuantao; Pi, Mingquan; Zhao, Huan; Ji, Jialin; Min, Yuting; Liang, Lei; Song, Fang; Zhang, Yu; Wang, Yiding; Tittel, Frank K.Nanophotonic waveguides hold great promise to achieve chip-scale gas sensors. However, their performance is limited by a short light path and small light–analyte overlap. To address this challenge, silicon-based, slow-light-enhanced gas-sensing techniques offer a promising approach. In this study, we experimentally investigated the slow light characteristics and gas-sensing performance of 1D and 2D photonic crystal waveguides (PCWs) in the near-IR (NIR) region. The proposed 2D PCW exhibited a high group index of up to 114, albeit with a high propagation loss. The limit of detection (LoD) for acetylene (C2H2) was 277 parts per million (ppm) for a 1 mm waveguide length and an averaging time of 0.4 s. The 1D PCW shows greater application potential compared to the 2D PCW waveguide, with an interaction factor reaching up to 288%, a comparably low propagation loss of 10 dB/cm, and an LoD of 706 ppm at 0.4 s. The measured group indices of the 2D and 1D waveguides are 104 and 16, respectively, which agree well with the simulation results.