Trigonal cluster-based ultra-sensitive surface plasmon resonance sensor for multipurpose sensing

We present an ultra-sensitive Surface Plasmon Resonance-based Photonic Crystal Fiber (SPR-PCF) sensor that can be employed for multipurpose sensing of analyte, temperature, and magnetic field. Our prototype has a trigonal cluster-based strategic pattern of circular air holes inside the fiber and can be easily fabricated using the standard Stack-and-Draw method. Thin layers of gold (Au) and titanium dioxide (TiO2) are used as the plasmonic materials surrounding the PCF. The Finite Element Method (FEM) of the commercial software COMSOL Multiphysics 5.3a is used to estimate the sensor properties. After optimization of different parameters, we recorded a maximum Amplitude Sensitivity (AS) of 7223.62 RIU−1, a maximum wavelength sensitivity (WS) of 28,500 nm/RIU, and a leading figure of merit (FOM) of 914 RIU−1. Our sensor is capable of detecting unknown analytes within the refractive index (RI) range of 1.33 to 1.42 with sensor resolutions of 1.38 × 10−6 (amplitude) and 3.51 × 10−6 RIU (wavelength). Furthermore, it can also detect temperature and magnetic field variations with the corresponding maximum sensitivity of 1.25 nm/°C (1250 pm/°C) and 0.16 nm/Oe (160 pm/Oe). An infinitesimal change in the sensor performance was observed for the ±10% fabrication tolerance analysis. So, it can be concluded that our sensor can significantly contribute to scientific, biomedical, and industrial fields due to its supreme sensing capabilities and versatile features.