Theoretical study of optimizing the refractive index sensitivity of dielectric–metal nanotube by tuning the geometrical parameters

Abstract

In this paper, we investigate the influences of inner core radius, shell thickness, dielectric function of inner core and surrounding medium on the refractive index sensitivity of dielectric–metal nanotube based on the quasi-static theory. Theoretical calculation results show that the refractive index sensitivity of dielectric–metal nanotube can be well optimized by tuning the geometrical parameters. The refractive index sensitivity of two-layered dielectric–metal nanotube increases exponentially with decreasing the wall thickness, but increases linearly with decreasing the refractive index of surrounding medium. In addition, the refractive index sensitivity of metal–dielectric–metal nanotube is also investigated, the calculation shows that the refractive index sensitivity of silver–dielectric–silver nanotube is higher than that of gold–dielectric–gold nanotube under the same parameter. The physical mechanism is investigated based on the plasmon hybridization theory. Our study provides a way to analyze and broaden the applications in sensor ability.