Waveguide controlled long range surface plasmon-polariton refractive index sensor

Abstract

A long range surface plasmon-polariton resonance (LRSPPR) based refractive index sensor (for biomolecular interaction study applications) with ultrahigh sensitivity and extremely narrow resonance dips with very small full width at half maximum (FWHM, w) is proposed. The theoretical analysis of the sensitivity for spectral and angular interrogations is presented. The structure consists of a MgF2 prism and a plasmonic waveguide (consisting of a metal cladded high index dielectric waveguide) separated by a low index dielectric layer. It is shown that both angular and spectral sensitivities increase nonlinearly with increase in analyte index. Angular sensitivity with FWHM = 0.009°, ranges from 340°/RIU to 505°/RIU for analyte index variation from 1.360 to 1.368 and spectral sensitivity with FWHM = 3 nm, ranges from 1.79 × 105 nm RIU−1 to 2.60 × 105 nm RIU−1 for analyte index variation from1.361 00 to 1.361 10. The sensitivities (S) and the figures of Merit of the proposed sensor are the highest obtained so far (to our knowledge).