Optically multiplexed multi-gas detection using quantum cascade laser photoacoustic spectroscopy

We report high-throughput, nondispersive optical multiplexing of laser beams using a scanning galvanometer. We have utilized this technique for multispecies trace-gas detection using multiple quantum cascade laser photoacoustic spectroscopy. We demonstrate switching from one laser to another in less than 1 s, a performance level needed for a comprehensive multispecies sensor, and a high signal-to-noise ratio detection of five gaseous components, NH(3), NO(2), dimethyl methyl phosphonate (DMMP, a simulant for nerve agents), acetone, and ethylene glycol, in a room air gas mixture containing approximately 3 ppb of NH(3), approximately 8 ppb of NO(2), approximately 20 ppb of DMMP, approximately 30 ppb of acetone, and approximately 40 ppb of ethylene glycol.