An ultra-sensitive medical sensor for low refractive index analytes

Abstract Detecting analytes whose refractive index (RI) below 1.3 has crucial medical applications. A D-shaped photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR), is proposed and simulated by the finite element method, and its sensitivity is optimized through tailoring distinct structure parameters. The simulation results indicate that in the broad RI range from 1.21 to 1.31, the wavelength sensitivity can reach up to 33 300 nm/RIU that greatly exceeds the existing PCF-SPR sensors for low RI detection, and the maximum figure of merit of 81 RIU −1 can be obtained.