Salinity Optical Sensor Based on Surface Plasmon Resonance Structure with As₂S₃ Waveguide

The surface plasmonic resonance (SPR) structure consisting of a gold film and amorphous chalcogenide film deposited on the base of a prism is analyzed. The chalcogenide amorphous film with high refractive index, like As2S3, forms plasmonic waveguide, which can maintain several modes of the electromagnetic field. The sensitivity of optical sensor based on SPR for measuring the salinity of aqueous salt solutions is studied numerically. A rutile TiO2 prism that couples the light with plasmons is considered. The considered wavelength is 1550 nm, which is proper for use in the infrared fiber optic networks. The calculations show that the resonance angle depends on the salt concentration and that the shift is enough to resolve salinity of different concentrations.