Numerical analysis of LSPR based fiber sensor for low refractive index detection

In this work, we have proposed localized surface plasmon resonance (LSPR) based optical fiber sensors using silver nanowires (AgNWs) for low refractive index (RI) detection. The sensing structure contains a semi-circular channel (SCC) incorporated with tightly placed multiple AgNWs inside the channel. The sensing behavior and the coupling phenomenon of the design are numerically investigated using full vectorial finite element method (FEM) based on COMSOL multiphysics. The sensing performance has been carried out by investigating optimized value of structural parameters such as channel separation (D), the radius of Ag nanowires (r(n)) and lastly the size of SCC (s). The proposed design exhibits a maximum sensitivity of 3725 nm/RIU for low RI analytes (n(a)) varying from 1.27 to 1.33. The proposed sensing structure is designed in such a way that it can be utilized in various sensing applications even with a small amount of measurand.