Hollow waveguide quantum cascade laser spectrometer as an online microliter sensor for gas chromatography

Microsensors based on quantum cascade lasers

“…We demonstrated that the coupling efficiency is over 50% for semiconductor epi lasers, e.g. QC lasers, due to QC laser's high brightness [3]. The transmission loss of HW is also quite low, only about 1-2dB/meter, making it an ideal platform for SA spectroscopy.…”

“…The bottleneck was that for blackbody sources used in FTIR, the light sources could not be efficiently coupled into capillary IR light waveguide, resulting in very short optical path, and also enlarged bore size and accompanying dilution by makeup gases which further degrade the performance of IRD [2]. With the advent and advances of Quantum Cascade lasers, we demonstrated that very high coupling efficiency for QC lasers into IR hollow waveguide (HWG) could be realized [3]. This effectively increased the pathlength of optical absorption to meters from inches, and with no sacrifice in markup gas dilution because the possibility to use small bore HWG.…”

Subsurface Monitor for Dissolved Inorganic Carbon at Geological Sequestration Site Phase 1 SBIR Final Report

“…QC lasers, into HW due to QC laser"s high brightness [15]. The transmission loss of HW is also quite low, only about 1-2dB/meter, making it an ideal waveguide to carry and deliver two different wavelength QC lasers over a short distance, e.g.…”

“…We also have built sample and hold circuitry for detecting pulsed QC laser signals with reduced noise. The results are presented in our effort/publication to measure CO2 gas molecules in the hollow waveguide with a pulsed QC laser [15]. An in-house dual channel Peak Sample and Hold circuitry (using TI"s OPA615 special Transconductance amplifier) have also been fabricated already for our other on-going project of detecting gas phase CO2 isotopomers in hollow waveguide as shown in figure 5.…”

Observation of whispering gallery modes in the mid-infrared with a quantum cascade laser: possible applications to nanoliter chemical sensing

“…For example, they could be used as inline sensor for Gas Chromatography (GC). With a one meter path length one could detect ppbV concentrations of CO 2 , which would exceed the sensitivity of the mainstream GC sensors [7].…”