Multi-component Trace Gas-identification System Based on Spectral Sensing Photodetector

A multi-component trace gas identification system based on spectral sensing photodetector is developed based on semiconductor near-infrared laser absorption spectroscopy. By analyzing the absorption spectral lines of different gas molecules in the near-infrared band, the absorption peaks of methane molecules near 1.653$\mu$m and hydrogen sulfide H 2 S molecules near 1.364$\mu$m were selected as the absorption spectral lines. The self-developed system mainly consists of laser, a long optical path gas absorption cell, a photoelectric detection module, data processing module and circuit, gas path, optical path, and several equipments. Using the Micro-Electro-Mechanical System Fabry-Perot Interferometer (MEMS-FPI) on-chip spectrum chip to detect the bandwidth (5 nm), the circuit is designed to make the sensor work with wider wavelength and higher filtering efficiency. It can realize synchronous detection with multi-wavelength infrared laser, realize the identification and concentration detection of a variety of gases with stable and high precision, and can effectively suppress the mutual interference of background gases. This system innovatively adopts the multi-channel wavelength modulation spectroscopy (WMS) technology of an addressable MEMS-FPI spectral chip to realize the trace detection of methane CH 4 , hydrogen sulfide H 2 S and other gas markers. At the same time, the system is equipped with the calibration technology of high-precision Photo Ionization Detector (PID) sensor, which takes into account the identification and detection of multicomponent gases, and greatly improves the detection accuracy.