Slab waveguide with conducting interfaces as an efficient optical sensor: TE case

Abstract

In this paper, three-layer slab waveguide structure is treated for optical sensing applications. Four waveguide configurations including different guiding films and analytes are assumed. A conducting two-dimensional free charge layers with a surface conductivity is assumed to exist at the substrate/film and film/cladding interfaces. The sensing sensitivity of the proposed structure to any changes in an analyte refractive index uniformly distributed in the cladding layer is investigated. Positive as well as negative surface conductivities are considered. It is found that utilizing positive surface conductivity can enhance the sensitivity, whereas using negative values of the surface conductivity reduces the sensitivity.