Photonic crystal fiber based on graphene surface plasmon resonance for high-sensitivity terahertz refractive index sensing

A photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) with a graphene coating on the cladding is designed for refractive index (RI) detection in the range of 0.3-0.5 THz, especially for liquid bioanalytical sensing. The adjustability of the graphene chemical potential (<i>E</i> _<i>f</i> ) enables dynamic tuning of the loss spectra over a wide frequency range with a tuning sensitivity of 570 GHz/eV at the SPR frequency. According to the analysis by the finite element method (FEM), the highest wavelength sensitivity and maximum amplitude sensitivity of 4254.11 µm/RIU and 25.62<i>R</i> <i>I</i> <i>U</i> ^-1 (<i>n</i> _<i>a</i> =1.34) are achieved in the RI range of 1.15-1.35, respectively, together with a resolution of 5.93×10^-5 <i>R</i> <i>I</i> <i>U</i>. The graphene PCF-SPR sensor boasting high-sensitivity detection in a wide RI range has broad application prospects in multiple fields.