Design of a dual spider-shaped surface plasmon resonance-based refractometric sensor with high amplitude sensitivity

Abstract

This study presents an investigation on the performance of the sensitivity of a dual spider-shaped surface plasmon resonance (SPR)-based photonic crystal fibre (PCF) refractive index sensor having unique design specifications. To evaluate the fibre guiding properties, Finite Element Method is used for utilising the monetarily accessible COMSOL Multiphysics version 5.3a. A gold layer has been used as the plasmonic material surrounding the fibre to ensure chemical stability, and a single fine coating of TiO₂ supported the improvement of gold attachment with the fibre. The structural air holes' design arrangement inside the PCF gives an enhanced sensitivity performance. The proposed PCF-SPR gives extremely reduced confinement losses. Numerous precise investigations on the fibre parameters show the highest amplitude sensitivity of 4233 RIU⁻¹ in detecting the scope of the refractive index (RI) 1.32–1.41. 2.36 × 10⁻⁶ and 1.18 × 10⁻⁵ and are achieved as amplitude resolution and wavelength resolution, respectively. The highest confinement loss found for this sensor is recorded to be 6.22 dB/cm. The RI sensor can lead to the exact identification of organic chemicals and biological analytes for the proposed design specifications, providing good sensitivity with significantly reduced confinement loss.