Investigation of wide-range refractive index sensor based on asymmetric metal-cladding dielectric waveguide structure

A refractive index (RI) sensor based on an asymmetric metal-cladding dielectric waveguide structure, in which an analyte is used as the guiding layer, is proposed in this report. The angular scanning attenuated total reflection spectra of the sensor and optical field distributions under waveguide mode resonance conditions were simulated, which confirmed that multiple waveguide modes can be used for sensing, and that different waveguide modes exist in different analyte RI ranges. The curves of both waveguide mode resonance angles and the sensitivity as a function of the analyte RI demonstrated that a wide sensing range can be achieved by combining waveguide modes of different orders. The proposed sensor could be applied to numerous fields, such as biological and chemical detection.