A multiple gas detection system based on a V-cavity coupled diode laser around 1550nm has been developed. The Vcavitycoupled diode laser exhibits side mode suppression ratio (SMSR) over 40dB and digitally switching over 20nm.The absorption lines of CO, CO_2 and H_2S are separately around 1567.3nm, 1573nm, 1578nm, which are distributed overthe tuning range of the diode laser. The technique of tunable diode laser absorption spectrum (TDLAS) is adopted in thegas detection for the advantage of high sensitivity and resolution. What’s more, the systems based on direct absorptionspectroscopy (DAS) and wavelength modulation spectroscopy (WMS) are established to measure gas concentration. As aresult, a linear relationship between detection signal and gas concentration is worked out and the R-square coefficient ofthe linear fitting is better than 0.99 for CO and CO_2.
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