Refractive index sensing based on graphene-hBN-silicon hybrid plasmonic rib waveguide

A graphene-hexagonal boron nitride ( ${h}$ BN)- silicon hybrid plasmonic rib waveguide (GHSHPRW) is designed for refractive index sensing which can be used as a biochemical sensor. The mode characteristics and propagation performances of the four hybrid plasmonic modes (HPMs) in the GHSHPRW are simulated by using the finite element method (FEM). The simulation results show that a high figure of merit ( FOM ) of 106 is achieved by optimizing waveguide size parameters. The propagation loss spectra of the four HPMs in the GHSHPRW with different parameters are discussed, which have remarkable peaks. The homogeneous and surface sensing performances of the GHSHPRW-based sensing structure are studied. The sensing performances shows that the sensitivities of -349.40 nm/RIU and 220 pm/nm are obtained for the homogeneous sensing and surface sensing, respectively. The detection limits ( DL s) of the homogeneous sensing and surface sensing can be better than 10−5 RIU and 14.97 pm when the standard deviation of the total noise in the sensing system is assumed to be 1.1 pm. The GHSHPRW-based sensing structure has small size, ultra-long propagation length, and good compatibility with the CMOS technology, so it has potential applications in the ultra-compact on-chip micro-nano photonic biochemical sensing system.