Highly sensitive gold-coated surface plasmon resonance photonic crystal fiber sensor in near-infrared region

Abstract

In this research paper, we propose a highly sensitive yet simple design hexagonal photonic crystal fiber (PCF) core-based surface plasmon resonance (SPR) refractive index (RI) sensor. The unknown target analyte and the plasmonic material, gold (Au) are placed at the exterior of the sensor surface for the feasibility of the operation. Twelve purely circular air-holes in two rings constitute PCF structure which makes the fabrication process realizable and practical. Numerical investigations are carried out utilizing the full-vector finite element method (FEM) to obtain the sensing performance of the PCF-SPR structure. After optimizing the structural parameters, the proposed PCF-SPR sensor obtains the highest wavelength sensitivity of 36000 nm/RIU and the highest amplitude sensitivity of 642.53 RIU-1, for an analyte RI range of 1.395 to 1.420 in the near-infrared wavelength regime (800 nm − 1200 nm). Aside from that, the sensor attained the maximum wavelength resolution and amplitude resolution of 2.77×10-6 RIU and 1.55×10-5RIU-1 respectively to assure excellent detection accuracy of smallest RI changes. Furthermore, the sensor achieved the highest Figure of Merit of 257.14 RIU-1. Thus, the proposed PCF-SPR sensor has the potential to detect unknown RI in a variety of applications including biosensing.