The Gold Coated Plasmonic Refractive Index Sensor with Low Propagation Loss

A refractive index (RI) sensor based on photonic crystal fiber (PCF) utilizing surface plasmon resonance (SPR) is modeled and numerically investigated. Gold, a chemically steady plasmonic material, is coated on the exterior of the sensor assembly. The sensor has been designed with COMSOL Multi-physics, and its transmission characteristics have been studied with the finite element method (FEM). The sensor structure consists of 24 circular air-holes, out of which 14 are bigger and 10 are smaller. The step-by-step optimized design shows enhanced sensing performance such as wavelength sensitivity of 22500 nm/RIU, amplitude sensitivity of -830.353RI$\mathrm{U}^{-1}$ and a Figure of merit (FOM) of 321.42 RI$\mathrm{U}^{-1}$. For accurate detection, the sensor reaches the maximum level of 4. $44\times 1 0^{-6}$ RI$\mathrm{U}^{-1}$ in wavelength resolution and 1. $28\times 10^{-5}$ RIU in amplitude resolution. The outer annular analyte channel, simple design, remarkable sensing characteristics, and very low propagation loss make the reported sensor a viable contestant in sensing and biosensing.