Theoretical Study on the Local Electric Field Factor and Sensitivity of Bimetallic Three-Layered Nanoshell Using Quasi-Approximation

Because of the coupling between nanoshell and core, the geometrical parameters of nanoshell have significant influence on the localized electric field factor (LEF) and sensitivity. In this paper, the effects of the inner core radius and the thickness of outer shell on LEF of gold-dielectric-silver (GDS) nanoshell and silver-dielectric-gold (SDG) nanoshell are investigated using quasi-static approximation. The result shows that the longer wavelength has a red-shift, while the shorter wavelength has a blue-shift as the inner core radius increases. The longer wavelength and the shorter wavelength mix together for LEF of GDS nanoshell with increasing the middle dielectric radius, while split for SDG nanoshell. Thus, the effects of geometric parameters on LEF of GDS nanoshell are different from that of SDG nanoshell. In addition, the effects of geometrical parameters on the sensitivity of GDS nanoshell and SDG nanoshell are also studied, a higher sensitivity of nanoshell can be obtained by varying the geometrical parameters. Our study provides a approach to study optical properties of GDS and SDG nanoshell and also broaden their applications in sensor.