Refractive Index Sensor Based on Surface Plasmon Resonance Excitation in a D-Shaped Photonic Crystal Fiber Coated by Titanium Nitride

In this paper, a plasmonic refractive index sensor using a D-shaped photonic crystal fiber coated by titanium nitride has been proposed. The interaction and interplay between fiber fundamental mode and plasmonic mode which lead to the formation of resonance peaks depending on the analyte refractive index (RI) are explained in detail. Using both spectral and amplitude sensitivity methods, the sensing performance of the proposed sensor for detecting high-index analytes is numerically investigated. The proposed PCF-SPR sensor has a RI detection range of 1.44 to 1.52 and exhibits two linear sensing regions with an average spectral sensitivity of - 16,275 nm/RIU for analyte RI ranging from 1.44 to 1.48, and - 7571 nm/RIU for analyte RI between 1.485 and 1.52, respectively. We also study the amplitude sensitivity of the proposed sensor which shows promising value of 206.25 RIU-1 for 1650-nm excitation. The proposed RI sensor is an attractive platform for detecting various high RI chemical and biochemical samples due to simple design, cost-effective plasmonic material, relatively large detection range, high sensitivity, and promising linear sensing performance.