Design of a balanced amplified photodetector based gas sensor

Dandan Sun

doi:10.1117/12.2503359

12 December 2018 Design of a balanced amplified photodetector based gas sensor

Dandan Sun

Proceedings Volume 10846, Optical Sensing and Imaging Technologies and Applications; 108460D (2018) https://doi.org/10.1117/12.2503359
Event: International Symposium on Optoelectronic Technology and Application 2018, 2018, Beijing, China

Abstract

In this paper, we report on the utilization of a novel background-free method for trace gas sensing. The classical combination of wavelength modulation spectroscopy and phase sensitive detection is replaced by a balanced amplified photodetector based differential detection system. Through a beam splitter, the transmitted laser beam from the gas medium is divided into the real-time and delayed branches. An optic fiber delay line is introduced to create a time-delay between the separated branches, and the following differential detection yields the derivative of absorption spectrum that is equivalent to the first harmonic in wavelength modulation spectroscopy. Via this straight-forward approach, the quantitative analysis of gas is performed in the absence of the background which is caused by optical intensity modulation. The gas sensor is validated using ammonia and nitrogen mixture in a laboratory controlled environment (296 K in temperature and 1.01×10⁵ Pa in total pressure), and yielding a detection limit of 6.4 ppm for ammonia. Experimental result shows the accuracy and potential utility of this gas sensor for industrial applications.

Citation Download Citation

Dandan Sun "Design of a balanced amplified photodetector based gas sensor", Proc. SPIE 10846, Optical Sensing and Imaging Technologies and Applications, 108460D (12 December 2018); https://doi.org/10.1117/12.2503359

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