Large-area fiber optic chemical sensors

Pacific Northwest Laboratory is developing a large-area chemical sensor that combines chemically coatings and optical spectroscopy to detect target compounds. The chemically selective material is incorporated into the cladding of an optical fiber waveguide. The material is interrogated using optical spectroscopic techniques to determine the concentration of target compounds. The optical interrogation method includes two spectroscopies: visible-near infrared absorption spectroscopy and Raman spectroscopy. This work develops the physical and mathematical models of such a sensor and provides a set of tools with which to make design predictions for the large-area chemical sensors. The theoretical relationships derived herein allow the use of bulk absorption parameters and bulk Raman coefficients to predict sensor performance.