Novel Single Hole Exposed-Suspended Core Localized Surface Plasmon Resonance Sensor

Abstract

Flexibility in design and controlling the wave- guide properties in photonic crystal fiber (PCF) has enabled diverse plasmonic sensing devices with attractive features. Here, we propose a novel single air hole exposed core PCF sensor based on localized surface plasmon resonance (LSPR) for bio-analyte sensing. To supports the LSPR, a gold (Au) nano strip is considered instead of continuous metal film making the proposed sensor cost-effective while experiencing low loss. A thin layer of titanium oxide (TiO2) is also used between the Au and silica glass to assist adhesion, which also contributes to enhancing the sensing performance. Considering the refractive index (RI) variation in the dielectric layer, the sensor performance analysis is carried out via finite element method (FEM) based commercially available software COMSOL Multiphysics in the visible to mid-infrared spectrum. According to numerical results, the proposed sensor shows maximum amplitude sensitivity (AS) of 1449 RIU−1 and a maximum wavelength sensitivity (WS) of 50,000 nm/RIU with a corresponding resolution of $2\times 10^{-6}$ in a wide RI range. Besides, being highly linear in sensing performance, the sensor attains low loss, with an improved figure of merit (FOM). Considering the simple architecture and competitive sensing performance, the proposed sensor could be used effectively in RI sensing applications, especially in bio-sensing.