Gas concentration sensor based on fiber loop ring-down spectroscopy

FLRDS technique is popular in recent years. It is an absorption spectroscopic and detection technique. It makes use of an optical cavity, which not only realizes a long effective path-length through a sample, but also eliminates the affection of fluctuations of the light intensity. In this paper, a kind of FLRD gas concentration sensor is presented. We analyze the structural parameters, including the couplers, pulse setting parameters, gas cell, and optimization methods of finding ring-down peak signal, etc. By the experimental data, this system can be reached that gas resolution is up to 1000 ppm, stability is 1.02%, and the repeatability error is 2.37%. Finally, we prove the superiority of the system.