Improving sensitivity of existing surface plasmon resonance systems with grating-coupled short-range surface plasmons

Abstract

Here we show that surface plasmon resonance sensors that typically use 760 nm wavelength Kretschmann–Raether coupling to a 50 nm thick gold film can have 3 times higher surface sensitivity by using local resonances from periodically arranged short-range modes in the same configuration. Considering shot noise, the resolution was found to improve fourfold. This was calculated by matching the design wavelength and minimum angle as calculated by rigorous coupled wave analysis, giving a period of 250 nm in a 10 nm thick gold film and a gap length of 40 nm. Finite-difference time-domain simulations were used to confirm that the short-range modes correspond to localized surface plasmon resonances. The present short-range plasmon approach can be used to improve the sensitivity in monitoring biomolecule interactions.