Abstract
A graphene/Si system, which is composed of a two-dimensional subwavelength silicon gratings and a graphene sheet, is designed to realize the complete band gap in infrared region for graphene surface plasmons (GSPs) theoretically. The complete band gap originates from the strong scatterings, which is caused by the periodical distribution of effective refractive index. The band structure has been calculated using the plane wave expansion method, and full wave numerical simulations are conducted by finite element method. Thanks to the tunable permittivity of graphene, the band structure can be easily tuned, which provides a way to manipulate in-plane GSPs’ propagation.
Highlights
Surface plasmons (SPs), originating from the interaction between free electrons of metal and the electromagnetic waves, hold potential applications in highly integrated optical devices, because they can break the conventional diffraction limit.[1,2] Recently, the development of graphene research provides the platform of controlling SPs at infrared frequencies.[3,4] Compared with the counterpart in the visible and near-infrared frequencies, which propagates along the noble metal surface, graphene SPs (GSPs) show attractive properties, including higher confinement and relatively low propagating loss.[5]
When electromagnetic waves propagate through Photonic crystals (PCs), band structures are formed by Bragg scattering
A GSPs analogy of photonic crystals is proposed in theory
Summary
Surface plasmons (SPs), originating from the interaction between free electrons of metal and the electromagnetic waves, hold potential applications in highly integrated optical devices, because they can break the conventional diffraction limit.[1,2] Recently, the development of graphene research provides the platform of controlling SPs at infrared frequencies.[3,4] Compared with the counterpart in the visible and near-infrared frequencies, which propagates along the noble metal surface, graphene SPs (GSPs) show attractive properties, including higher confinement and relatively low propagating loss.[5]. Light with a wavelength within the PBGs is not allowed to propagate through the PCs. Due to special dispersion relations of PCs, various novel optical phenomena are investigated, such as self-collimation,[16] superlens,[17] negative refraction,[18] and subwavelength imaging.[19] Besides, a SPs analogy of photonic crystals is investigated both experimentally and theoretically, which provides a platform to manipulate the propagation of in-plane SPs.[20] But, the actively controllable band structures are barely investigated, and the research progress of GSPs offers a possible way. Because the surface conductivity of graphene can be tuned by bias voltages or chemical doping, the band structure for in-plane GSPs can be actively controlled, which provides a platform to manipulate GSPs’ propagation
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