Dual-channel D-shaped refractive index sensor based on photonic crystal fiber

This study numerically proposed and analyzed a wide-range surface plasmon resonance refractive index sensor based on a dual D-shaped photonic crystal fiber. The design employs an external sensing mechanism, with a gold film deposited as the plasmonic material on the outer surface of the elliptical groove, ensuring feasible fabrication. The proposed sensor is capable of detecting analytes within a refractive index range of 1.20–1.36, achieving a maximum spectral sensitivity of 14,000 nm/RIU. Additionally, it supports amplitude-based detection, offering a maximum amplitude sensitivity of −101.99 RIU−1. The study systematically examines the effects of key design parameters, including the air hole diameter, spacing between air holes, and gold film thickness, among others. With its wide detection range, high sensitivity, ease of fabrication, and user-friendly design, the proposed sensor demonstrates significant application potential in detecting fluorinated organic compounds, medical anaesthetics, liquid carbon dioxide, and other analytes.