An ultra-compact tunable Bragg reflector based on edge propagating plasmons in graphene nanoribbon

A mid-infrared planar Bragg reflector, which is based on the fundamental edge plasmonic mode in the nanoribbons is proposed and numerically demonstrated in this paper. The simulation results calculated with the three-dimensional (3D) finite element method reveal that it shows superb wide-band filtering characteristics in the mid-infrared frequencies, and the bandwidth of stopband in the reflector can be dynamically modulated by varying the chemical potentials of corresponding nanoribbon waveguides. In addition, its band properties on the ribbon width are also analyzed. This kind of Bragg reflector exhibits extreme compactness of lateral scales and wonderful light confinement in both the longitudinal and the lateral directions, which is expected to have significant applications in constructing 3D highly integrated optical networks for signal processing.