Excitation of crest and trough surface plasmon modes in in-plane bended graphene nanoribbons

To achieve efficiently coupling to external light is still remaining an insurmountable challenge that graphene faces before it can play an irreplaceable role in the plasmonic field. Here, this difficulty is overcome by a scheme capable of exciting graphene surface plasmons (GSPs) in inplane bended gratings that are formed by elastic vibrations of graphene nanoribbons (GNRs). The gratings enable the light polarized perpendicularly to the GNRs to two kinds of GSP modes, of which the field concentrations are within the grating crest (crest mode, C-M) and trough (trough mode, T-M), respectively. These two kinds of modes will individually cause notches in the transmission spectrum and permit fast offon switching and tuning of their excitation dynamically (elastic vibration, Fermi energy) and geometrically (ribbon width). The performance of this device is analyzed by finite-difference time-domain simulations, which demonstrates a good agreement with the quasi-static analysis theory. The proposed concept expands our understanding of plasmons in GNRs and offers a platform for realizing of 2D graphene plasmonic devices with broadband operations and multichannel modulations. (C) 2016 Optical Society of America