Design and Numerical Analysis of Photonic Crystal Fiber Based Refractive Index Sensor

Abstract

Over the span of past decade, photonic crystal fiber (PCF) sensors utilizing surface plasmon resonance (SPR) phenomenon have shown marvelous headway. Numerous scientists have proposed a more extensive scope of SPR-based sensors at this point. However, a considerable amount of these proposed sensors either show low affectability or it is exceptionally hard to manufacture the sensors for ongoing applications. We have developed a PCF SPR sensor that has circular-shaped air holes which is easy to fabricate as well as shows high sensitivity in the visible and near-infrared spectroscopy. We have used a layer of gold covering the cladding layer of the PCF structure to generate surface plasmon excitation. An external layer is applied to minimize emission of light from the fiber core. The guiding properties and analytical evaluation are carried out using the COMSOL Multiphysics on the basis of finite element method. In x-polarization mode, the suggested structure gives maximal value of amplitude sensitivity and wavelength sensitivity (WS) of 1757.3RIU−1 (Refractive Index Unit) and 32,000 nm/RIU respectively. In addition to that, the proposed design exhibits high sensor resolution of 1.428×10–6 and figure of merit of 587.2 indicating a high-performance sensor and demonstrates birefringence of 0.004 RIU. Moreover, the proposed PCF-SPR sensor is composed of only six symmetrical circular air holes, which makes it fabrication friendly. For our next design, we have focused on reducing confinement loss and simultaneously increase wavelength sensitivity. Here we have used a single layer of hexagonal shaped lattice with circular air holes. The proposed design gives maximal AS of 1072.5 RIU-1, peak WS of 41,000 nm/RIU, and sensor resolution of 2.4×10-6 considering the xpolarization mode. The high performance of the proposed sensor and high fabrication probability makes the sensor a strong contender to be used in biomedical and biochemical applications.