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

Abstract

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.

Diode Laser Spectroscopic Monitoring of Trace Gases

“…(54) With their high output power (up to several hundreds of milliwatt) in single-mode operation, QCLs are particularly attractive for gas-sensing applications and have been used with the most sensitive spectroscopic techniques, including long path length, (55) balanced detection, (56) WMS, (57) FMS, (58) OAS, (59) and CRDS, (60) and their room-temperature operation capability (at least in pulsed mode) makes these lasers well suited for field applications.…”

High-power high-wall plug efficiency mid-infrared quantum cascade lasers based on InP/GaInAs/InAlAs material system

“…Techniques such as photoacoustic spectroscopy have been used in the infrared "fingerprint" region to determine very small concentrations of target chemicals with high speed and accuracy [1,2]. However, this technique requires a light source with high average power.…”

“…Meanwhile, QCL based applications, such as photoacoustic spectroscopy [2], remote sensing [8], and free space communication [9], are also experiencing rapid development, thanks to the availability of efficient high power QCLs.…”

Biphenyl derivatives containing trimethylsilyl benzyl ether or oxime groups as probes for NO2detection

“…Laser-based photoacoustic spectroscopy, 8 surface acoustic wave (SAW), 9 transition metal oxide devices, 10 carbon quantum dot-functionalized aerogels, 11 or ozone treated graphene 12 are some reported analytical techniques used to detect/monitor NO 2 levels. However, some of these methods show certain limitations such as lack of specicity, limited selectivity, operational complexity, non-portability, difficulties in real-time monitoring and false positive readings.…”