Cavity-enhanced absorption detection of H₂S in the near-infrared using a gain-switched frequency comb laser

A custom-designed gain-switched frequency comb laser was passively coupled of to a medium-finesse cavity in the region between 6346 and 6354 cm⁻¹ for the development of a prototype cavity enhanced absorption setup. The setup was applied to static gas detection of hydrogen sulfide at the parts per thousand level in a laboratory environment. A Fourier transform spectrometer was used for signal detection. The experimental performance of the setup was characterized in this proof-of-principle investigation; advantages, drawbacks and future scope of the approach are discussed in this article.