Dual-band D-shaped SPR fiber sensor based on birefringence analysis

Abstract We propose and numerically investigate a dual-band D-shaped surface plasmonic resonance (SPR) fiber sensor, which consists of a simple D-shaped fiber with metallic nanowire grating on the polished flat surface. The correlation between resonance coupling and degenerate mode properties are fully investigated based on birefringence analysis. To the best of our knowledge, it is the first report that plasmon resonances occurs in both directions which are parallel and perpendicular to the polished surface in this simple structure. The sensing figure of merit (FOM) of the two orthogonally SPR modes reach up to 200 and 190 RIU−1. The proposed structure would be a good candidate for dual-channel biosensing, medical diagnosis and environmental monitoring in a wide refractive index range of 1.31–1.37.