iHWG-ICL: Methane Sensing with Substrate-Integrated Hollow Waveguides Directly Coupled to Interband Cascade Lasers

Abstract

The development of a compact iHWG-ICL gas sensor combining innovative substrate-integrated hollow waveguides (iHWG) with mid-infrared emitting type-II interband cascade lasers (ICL) is presented. Hence, tunable laser absorption spectroscopy (TLAS) with iHWGs in direct absorption mode is enabled. Using a room-temperature distributed feedback (DFB) ICL emitting at approximately 3.366 μm, quantitative sensing of methane was demonstrated. Wavelength scanning was obtained via current tuning for monitoring an isolated line in the v3 fundamental band of CH4. The obtained spectra were compared to calculated spectra derived from the HITRAN2012 database. Furthermore, the performance of iHWGs simultaneously serving as miniaturized gas cell and as efficient optical waveguide at various absorption path lengths was tested and optimized. Calibration functions in the concentration range of 50 to 400 ppmv were established enabling limits of detection ranging from 6 to 28 ppmv. Hence, the combination of iHWGs with ICLs facilitates a new generation of compact optical sensor devices for rapid gas diagnostics in low sample volumes.

Infrared spectroscopy via substrate-integrated hollow waveguides: a powerful tool in catalysis research

“…It is anticipated that further improvements in time resolution will be facilitated by using advanced infrared light sources coupled to iHWGs including quantum cascade lasers (QCLs) 20 and interband cascade lasers (ICLs). 12,21 In summary, it is apparent that IR-iHWG analyzers provide unique capabilities for studying transient gas phase reactions during catalytic conversion processes at reasonably short time scales, and should thus find broad application in heterogeneous catalysis research.…”

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

“…Recently, new types of gas cells have been developed to achieve long optical path in a smaller volume, including modified MPCs [111][112][113][114][115][116], circular multi-reflection (CMR) cells [117][118][119][120][121][122][123][124], and HWG [32,63,69,[125][126][127][128]. Guo and Sun reviewed the progress in modified MPCs and CMR cells and compared them in terms of optical pathlength (OPL), volume, and path-to-volume ratio (PVR) [116].…”

Quantitative Analysis of Gas Phase IR Spectra Based on Extreme Learning Machine Regression Model

“…To collect real spectra, Fourier transform infrared (FTIR) spectroscopy was used in combination with substrate-integrated hollow waveguide (iHWG) technology simultaneously serving as highly efficient gas cell [36][37][38]. Compared with other sensor technologies such as electrochemical and semi-conductor-based devices, IR spectroscopy/sensing enables monitoring multiple gas components even in complex mixtures.…”