A plasmonic refractive index sensor with double self-reference characteristic

Abstract

A plasmonic refractive index (RI) sensor with self-reference performance based on one-dimensional (1D) rectangular grating coupling is proposed. The TM polarization reflection characteristics and the electric field distributions are extracted via using the finite-difference time-domain method. Numerical simulation results and theoretical analyses show that 1D rectangular grating can excite multiple propagating surface plasmon resonances with gold thin film as a carrier. One of the resonance modes shows considerable performance in RI sensing due to its wide interaction with the analyte environment, which can achieve a high RI sensitivity of 1001 nm /RIU and the figure of merit of 203.4 RIU. More importantly, two resonance modes independent of the analytes can be used for self-references to counteract sensing errors caused by external instability factors such as temperature and light intensity fluctuations. This sensor can realize important practical sensing applications in the situation of unstable and complicated environments.