Refractive Index Sensor Based on Surface Plasmon Resonance Excitation in a D-Shaped Optical Fiber Coated by Tantalum

In this paper, a plasmonic refractive index sensor using a D-shaped optical fiber coated by tantalum has been proposed. The interaction between fiber fundamental mode and plasmonic mode which lead to the formation of resonance peaks depending on the analyte refractive index (RI) is investigated in detail. Using spectral sensitivity methods, the sensing performance of the proposed sensor for detecting analytes is numerically studied. The effect of various design parameters of proposed sensor is optimized numerically to achieve the maximum wavelength sensitivity. The proposed D-shaped optical fiber sensor has a RI detection range of 1.30 to 1.43 and exhibits a non-linear increasing spectral sensitivity from 1300 to 3900 nm/RIU. The proposed RI sensor is attractive for detecting different RI chemical and biochemical samples due to simple design, relatively large detection range, cost-effective, non-toxic nature, and highly corrosion resistivity plasmonic material.