High Sensitivity of Phase-based Surface Plasmon Resonance in Nano-cylinder Array

Surface plasmon resonance sensor is used to measure the variation of dielectric constant sample, but its sensitivity is limited to surrounding temperature fluctuation. We present a high sensitivity phase-based surface plasmon resonance sensor made by gold nano-cylinder array. This structure is not only to reduce thermal conduction by the non-continuous gold array, but also to enhance surface plasma by these nano-size surfaces. This device consists of 160 nm diameter, 400 nm height gold cylinders on 47 nm gold film coated on Corning 1737 glass, and match with BK7 prism by NuSil LS-5252 optical matching liquid. Surface plasma wave was excited by a 632.8 nm HeNe laser irradiating on this prism at a particular angle. The phase variation between the signal light and reference light are collected by a pair of photo-detectors and recorded by a lock-in amplifier (Stanford Research 830). By considering heterodyne interference optical path, the sensitivity of this tool can reach 10−7 RIU.