Self-reference plasmonic sensor with ultranarrow linewidths based on SPP and cavity resonances

A self-reference plasmonic sensor is numerically demonstrated on surface plasmon polaritons (SPP) and cavity resonances. The sensitivity of the SPP mode is up to 1220 nm RIU(-1)for detecting refractive index variations. The cavity mode is insensitive to refractive index variations, which is used to monitor the environment variations. Owing to the low radiative loss of the SPP mode propagating on a smooth silver surface, an ultranarrow linewidth (0.9 nm) of SPP mode is obtained. Benefiting from high sensitivity and ultranarrow linewidth, the figure of merit (1356 RIU-1) is much larger than that (31 RIU-1) of reported self-reference plasmonic sensors.