The authors demonstrate a highly sensitive chemical sensor scheme based on Si/sub 3/N/sub 4/ channel waveguides, species-selective surface coatings and Zeeman interferometry. The relative phase change between the TE and TM modes under exposure to toluene vapour is measured. The measurements demonstrate the real-time and reversible response with good sensitivity at low concentrations.
Grace, K., Shrouf, K., Honkanen, S., Äyräs, P., Katila, P., Leppihalme, M., Johnson, R., Yang, X., Swanson, B., & Peyghambarian, N. (1997). Waveguide zeeman interferometry for thinfilm chemical sensors. Electronics Letters, 33(19), 1651-1653. https://doi.org/10.1049/el:19971108