The detection of (toxic) gases in our environment is of paramount importance for air quality monitoring, fire risk assessment, etc. In FireSpec miniaturized spectroscopic sensing units have been developed, aiming at the real-time, sensitive and specific detection of particular gas molecules. For that purpose, semiconductor laser sources operating in the 1.5-2.5um wavelength range and integrated on a silicon photonic chip were developed, together with the necessary drive electronics. By integrating these sources, the size and cost of such systems reduces substantially, allowing such systems to be used in portable applications, e.g. to be used by fire fighters to measure toxic gases on an accident site or to be mounted on a drone for areal mapping of gas concentrations. As each gas has a specific absorption spectrum, lasers covering a broad wavelength range need to be integrated. In this project, we demonstrated the realization of an array of single wavelength lasers integrated on silicon covering the 2.275 um – 2.425 um wavelength range, overlapping with the absorption spectrum of e.g. NH3, HF, CO and CH4. We also demonstrate a widely tunable laser on silicon covering 2.01um – 2.07 um, of particular interest for CO2 and H2O monitoring. Finally, we demonstrate a new technology to integrate lasers made of different III-V semiconductor layer stacks (and hence emitting at very different wavelengths) on a single chip, allowing for advanced laser sources for multi-gas sensing. We showcase the use of these sources in the detection of CO (using tunable diode laser spectroscopy) and CO2 (wavelength modulation spectroscopy), for which the required driver electronics was developed as well.
