Study of the gap influence on highly sensitive plasmonic nanosandwich for refractive index sensing

In this paper, we present a novel design of a nanosandwich antenna array used for refractive index sensing. The nanosandwich sensor consists of two gold rings with centered gaps separated with a silica disk spacer. The optical properties of the nanoantenna structure are investigated. The influence of the gaps in the upper and lower rings on the nanoantenna field enhancement and spectral response is discussed. This nanosandwich design is very suitable for biosensing applications due to its strong field enhancement and high sensitivity that reaches 1552 nm/RIU.