Detection of explosive analytes using a fiber-based optical Fabry-Perot gas sensor

We demonstrate the rapid detection of explosive vapors based on a fiber-based optical Fabry-Perot (FP) gas sensor. The sensing probe of the FP sensor is composed of a thin metal layer and a vapor-sensitive polymer layer that are deposited sequentially on a cleaved fiber endface to form an FP cavity. The interference spectrum generated from the reflected light at the metal-polymer and polymer-air interfaces changes upon the absorption of gas analyte. By monitoring the interference shift, we are able to obtain quantitative and knetic information of the interaction between the analyte and the polymer layer. We further assemble the FP sensor with a short fused silica capillary into a sensor module, and employ it in a gas chromotgraphy (GC) system for selevtive rapid on-column detection. In this report, we specifically target 2, 4- dinitrotoluene (DNT) and 2, 4, 6-trinitrotoluene (TNT) for their obvious defense applications. This work could lead to a portable sensor capable of detecting low concentrations of DNT, TNT, and other explosive chemicals.