Detection of ethanol and water vapor with silicon quantum dots coupled to an optical fiber

The end facet of a standard multimode optical fiber was coated with fluorescent silicon quantum dots (Si-QDs) and used as a probe to detect water and alcohol vapors as a feasibility study for sensing applications. In this work, the response of the sensor to different analytes was observed, and the repeatability of the sensor response was investigated. When exposed to different vapors, the luminescence intensity of the Si-QDs varied over timescales of a few seconds to hours. By coupling the QDs to an optical fiber splitter, fiber-based measurements were demonstrated for ethanol and water vapor. At this stage, the Si-quantum-dot-based fiber sensing shows a fast response time and reasonable detection limits, but true quantification remains difficult owing in part to sample-to-sample variations.