Sharp Asymmetric Line Shapes in a Plasmonic Waveguide System and its Application in Nanosensor

A sharp and asymmetric line shape is numerically predicted in a novel and compact plasmonic waveguide system. This system consists of a groove and a ring resonator coupled with a metal-insulator-metal waveguide. Due to the interaction of the narrow discrete resonance and a broad spectrum caused by the ring resonator and the groove, respectively, the transmission spectrum exhibits a sharp asymmetrical profile. Simulation results show that the spectral line shape can be easily tuned by changing the parameters of the structure. The physical features contribute to a highly efficient plasmonic nanosensor for refractive index sensing with the sensitivity of 1160 nm/RIU and a figure of merit of 3200. This plasmonic structure with such high figure of merits may find important applications in the on-chip nanosensors.