Thin-film chemical sensors with waveguide Zeeman interferometry

We describe a highly sensitive chemical sensor scheme using a channel waveguide with a selective surface coating based on polarimetric Zeeman interferometry. The sensing is based on measurement of the phase difference between TE and TM modes propagating in the anisotropic waveguide structure under exposure to toluene vapour. A real-time and reversible response at low ppm level is observed. Modelling results of the sensor structure to further increase its sensitivity are presented.