Evanescent-Wave Gas Sensing Using an Integrated Thermal Light Source

The last years showed an increased request for miniaturised, CMOS-compatible gas detectors. In contrast to sensors utilizing metal-oxide chemical interfaces, optical strategies are potentially faster and more robust. Recently we demonstrated CO2 detection by evanescent-wave absorption in the mid-infrared using a combination of an external laser source and silicon waveguides based on CMOS technology. We now go one step further and demonstrate the feasibility of detection of CO2 down to a concentration of 3% with a low-cost integrated thermal source. These results are promising for further technological developments towards on-chip mid-infrared photonic gas sensors, and new designs are currently devised to increase the yet relatively low sensitivity.