Thin film waveguide sensors for chemical detection

A chemical sensor scheme, based on selective sensing surfaces and highly sensitive integrated optical transduction is presented. Self-assembly techniques are used to covalently attach species selective films onto the surface of silicon nitride waveguides. Exposure to targeted analytes results in selective absorption of these molecules onto the waveguide surface, causing a change in the effective refractive index of the guided modes. These relative changes in effective refractive indices of TM and TE modes are measured using Zeeman interferometry. The measurements demonstrate reversible, real time sensing of volatile organic compounds at ppm level. Improvements in the waveguide design are proposed to further increase the sensor performance.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.