▎ 摘　　要

NOVELTY - The method involves arranging a portion of a layer of graphene (102) to provide conductivity. Another portion of the layer of graphene is arranged to provide another conductivity, where a curved or linear interface (108) is provided between the two portions. The interface is arranged to guide an optical signal. The optical signal is attenuated with a third portion e.g. lens. A set of tomograms is determined based on a set of gradients. The optical signal is coupled to the layer of graphene via a defect in the layer of graphene, prism coupling, and via evanescence. USE - Method for guiding an optical signal on layers of graphene to create an optical device e.g. ribbon waveguide beam combiner or splitter, ribbon waveguide mirror, ribbon waveguide scattering device, ribbon waveguide attenuating device, ribbon waveguide lens device, metamaterial, ribbon waveguide Fourier optic, ribbon waveguide Luneburg lens (all claimed). ADVANTAGE - The method enables providing lower material loss in graphene so as to provide longer propagation length for a surface plasmonic polariton (SPP) wave along the graphene, and providing wave number of the SPP wave along the graphene to be larger than the free space wave number so as to confine SPP optical waves tightly to the graphene layer. The method enables changing the conductivity of the graphene in a dynamic manner by using chemical doping or gate voltage in real time locally and in homogeneously. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a device for guiding an optical signal, comprising a layer of graphene. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a linear interface, which acts as a waveguide in a layer of graphene. Graphene (102) Distinct areas (104, 106) Linear interface (108)