Bimetallic surface plasmon resonance photonic crystal fiber biosensor using refractory plasmonic material

Surface plasmon resonance (SPR) photonic crystal fiber (PCF) biosensors have recently attracted the attention of many researchers due to their unique properties which paved the way for many applications. Unlike the conventional configurations of SPR, the PCF-based sensors make remote sensing and real-time detection feasible. In addition, it is required to remove the conventional fiber cladding for obtaining a high sensitivity. In this paper, the use of Titanium Nitride (TiN) as a refractory plasmonic material in a highly sensitive plasmonic PCF is presented and analyzed by full vectorial finite element method. The proposed design relies on a silver layer as a plamonic material. Further, a thin coating layer of the abrasion-resistant alternative plasmonic material TiN is used to protect the silver layer from oxidation. In this investigation, the Ag/TiN configuration achieves high refractive index sensitivities of 9400 nm/RIU for both quasi-transverse electric (TE) and quasi-transverse magnetic (TM) modes by optimizing the design geometrical parameters. It is found out that the resonant peaks corresponding to the two polarized modes are extremely sensitive to the analyte refractive index variations. Moreover, the performance of the suggested design has high linearity. To the best of the authors’ knowledge, it is the first time to introduce TiN in a bimetallic PCF biosensor as a plasmonic material with high sensitivity.