Towards miniaturized gas sensors based on substrate-integrated hollow waveguides and interband cascade light emitting diodes

Abstract

In this study, we report the first combination of mid-infrared (MIR) interband cascade light emitting diodes (ICLEDs) with a central emission wavelength at 4.0 μm and 3.4 μm, respectively, combined with a substrate-integrated hollow waveguide (iHWG) for the detection of CO₂ and CH₄ analyzing the antisymmetric stretching of CO₂ at 2345 cm⁻¹, and the CH stretching rovibrational mode of CH₄ at 3020 cm⁻¹. The obtained calibration functions in the concentration range from 1000 to 10 000 ppm_V enabled deriving detection limits in the range of 386–407 ppm_V for CO₂, and of 302–338 ppm_V for CH₄. The combination of iHWG and ICLED technology is a pioneering step toward a new generation of miniaturized and low-cost mid-infrared optical sensing devices for rapid gas diagnostics and exceedingly small sample volumes.