Dual-polarized ultrahigh sensitive gold/MoS2/graphene based D-shaped PCF refractive index sensor in visible to near-IR region

Abstract

We propose a surface plasmon resonance based D-shaped photonic crystal fiber (PCF) refractive index (RI) sensor in visible to near-infrared spectrum. It is suitable for the detection of biomedical/biochemical analytes within the different analyte refractive indices ranging from 1.33 to 1.40. Gold is used as an active metal deposited on the partially removed cladding of the D-shaped PCF. Subsequently, a thin layer of molybdenum disulfide (MoS2) is deposited on the gold because it supports intensive confinement of plasmon polaritons with low loss. Further, a flake of graphene is deposited on MoS2 layer as it provides oxidation resistance to gold and MoS2 layers. MoS2 improves the sensing characteristics of the proposed D-shaped PCF due to its high surface adsorption efficiency and excellent band gap tunability. Moreover, the structure parameter such as the diameter of the largest air hole and the thickness of gold, graphene and MoS2 layer is varied to observe its effect on sensing performance of the proposed PCF. The simulation result showed that the sensitivity was improved and reached to 14,933.34 nm/RIU (refractive index unit) with a high figure of merit and an effective RI resolution of 401.05 RIU−1 and $$6.69\times {10}^{-6}$$ RIU, respectively. With such sensing characteristics, our proposed sensor can be a potential candidate in plasmonic sensors.