Surface plasmon optical sensor based on multilayer metal-coated nanorods resonator

An optical sensor of seven metal-coated nanorods periodically distributed on a circular ring is designed. Based on the T-matrix method, scattering properties of periodic structures are investigated theoretically. The numerical result shows three resonant peaks in the scattering cross section (SCS) when the gap between the nanorods is tiny. The values of three resonant peaks vary linearly with the refractive index in the cavity formed by the nanorods. By adding gain/loss material into the inner dielectric nanorods, the peak and Q values of resonance frequencies increase and enhance sensor sensitivity.