D-shaped silicon core fiber-based surface plasmon-resonance refractive index sensor in 2  µm

In this paper, we propose a D-shaped silicon core fiber sensor based on surface plasmon resonance within the 2 µm range. Au layer coating on the D-shaped side-face of silicon core fiber acts as a plasmonic active metal. By using the limited element methods, the sensing properties of the proposed sensor are investigated, and an average sensitivity up to 2650 nm/RIU with a resolution of 3.776 × 10 − 5 R I U is obtained for the analyte of different refractive indices varies from 1.25 to 1.6. In the investigated simulation, we used real parameters of liquid (e.g., C H 4 liquid and C H B r 3 ) in our simulations for being closer to reality. In addition, the Au coating layer and analyte are placed on the D-shaped side-face of the proposed fiber sensor; hence, this structure does not need to fill the voids. Thus, it is easy to fabricate and put to use. Also, the wavelength band in 2 µm is far from the optical communication band, which means the proposed sensor could be connected with a fiber network without any influence and crosstalk.