The absorbance enhancement investigation of multiple gas absorption lines based on ICFRL

The absorbance enhancement of multiple gas absorption lines is investigated by simulations and experiments in this paper. The relationship between cavity loss and gas absorbance of different absorption lines is simulated based on rate equation. For the purpose of using simple arithmetic mean instead of weighted arithmetic mean in calculating gas concentration by multiple absorption lines, the absorbance equality method is proposed and simulated. To verify the simulations, some experiments were carried out based on the intra-cavity fiber ring laser (ICFRL) gas sensing system. The experimental results of absorbance enhancement extremely match to the simulation results. More than 40 C2H2 absorption lines can be observed and a minimum detectable C2H2 concentration of 200 ppm is acquired according to the experiments.