Mid-infrared photonic gas sensing using a silicon waveguide and an integrated emitter

Abstract The miniaturization of optical gas sensors is of interest for automotive and consumer electronics. We recently presented the use of silicon waveguides for evanescent-field gas detection in the mid-infrared by using an external laser source. However, the feasibility of the method is not guaranteed when the laser source is replaced by an integrated light source, typically a thermal emitter, due to the lower emitted power of the latter. Here, after experimentally characterizing the evanescent-field ratio of the fabricated structures, we demonstrate the feasibility of gas detection using a silicon waveguide and a low-cost integrated thermal emitter. Specifically, using the first demonstrators we achieve CO 2 detection down to a concentration of 10% with a confidence level of three standard deviations. The current detection limit is close to that previously measured with an external laser source and it is mainly limited by the yet not-optimized waveguide structure. This research represents a promising advancement for the development of fully-integrated photonic gas sensors in the mid-infrared.