Goos–Hänchen shift as a probe in evanescent slab waveguide sensors

Abstract

The present paper deals with three-layer planar waveguide optical sensor. Different from the conventional slab waveguide sensors in which the effective refractive index of the propagating mode is taken to be the probe for detection changes in the analyte refractive index, we adopt Goos–Hänchen (GH) shift as the sensing probe for the proposed sensor. We show that the GH shift is strongly dependent on the refractive index of the cladding, thus it is a good candidate for detection changes in the analyte refractive index. We present and study the sensitivity of the GH shift at the cladding–film and substrate–film interfaces. It is found that GH shift has a high sensitivity and can be used for versatile optical slab waveguide sensors.