Trace Gas Detection System Based on Photoacoustic and Photothermal Spectroscopy Using Ring Fiber Laser and Quartz Tuning Fork

Bi, Shaoqiang; Qian, Shen‐En; Tian, Cunwei; Zhang, Qinduan; Yu, Yuanfang; Wang, Zongliang

doi:10.1109/jsen.2023.3244027

Cited by 5 publications

(1 citation statement)

References 28 publications

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“…A common part of many optical gas sensing principles is a gas cell, which contains the analyzed gas that is illuminated by excitation light with wavelengths aligned to the absorption peaks of the target species within the analyzed gas. The absorption of light by target species is then identified by using different principles, like gas absorption spectroscopy [3], tunable diode laser absorption spectroscopy (TDLAS) [1], photo-acoustic absorption spectroscopy [4], measurement of the anomalous dispersion of refractive index [2], and many others. While these sensing principles are well established, gas absorption cells remain relatively large (long optical path lengths are required), complex for production (which is associated with increased cost), require relatively large sample volumes, are sensitive to vibrations, temperature, and other environmental impacts, and have limited compatibility with optical fibers.…”

Section: Introductionmentioning

confidence: 99%

Gas Sensing System Based on an All-Fiber Photothermal Microcell

Njegovec,

Javornik,

Pevec

et al. 2024

IEEE Sensors J.

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This paper presents an all-fiber, miniature Fabry-Perot gas sensor based on photothermal absorption spectroscopy with a custommade and cost-efficient interrogation system. The sensing gas microcell has a diameter of 125 μm, a length of 1 mm, and allows for free gas exchange within the optical resonator through micromachined slits. High light intensity and confinement is ensured by delivering the excitation light directly into the gas microcell through a lead-in singlemode fiber. This enhances the photothermal effect and provides a short system response time. The interrogation system utilizes the modulation of an excitation laser diode with a fixed frequency while locking the probe laser onto the gas microcell's quadrature point and observing the variations of the reflected optical power. To show the potential of the proposed system, nitrogen dioxide was measured in dry air. Thereby, a limit of detection of 20 ppm could be achieved for 10 seconds` integration time. Furthermore, the small dimensions of the sensor allow for improved dynamic performance with photothermal modulation frequencies as high as 7 kHz.

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