High performance dielectric loaded graphene plasmonic waveguide for refractive index sensing

Abstract

In this study, a new dielectric loaded plasmonic waveguide is proposed by inserting a vertical graphene layer into the dielectric ridge in order to realize propagation of SPP waves symmetrically on both sides of the graphene. This waveguide is numerically analyzed for sensing applications at the wavelength of 1550 nm. The effective refractive indices of its guided modes are calculated by the full-wave modal analysis based upon finite element method. The guiding and sensing properties of the biosensor based on the desired mode of the presented waveguide is investigated for several values of structural parameters and compared with dielectric loaded graphene surface plasmon polariton waveguide (DL-GSPPW). The results show that not only the suggested waveguide is more suitable for sensing applications as compared with other dielectric loaded plasmonic waveguides, but also it can be an appropriate candidate for ultra-compact optical interconnects in the integrated photonics owing to the strong confinement of the optical field inside the ridge. By considering optimized dimensions of the ridge for an improved sensing performance, the biosensor based on suggested waveguide has high sensitivity up to 9.2 W/RIU with a minimum limit of detection (resolution) equal to 0.43 μRIU.