Tunable broadband transmission and phase modulation of light through graphene multilayers

In this work, we study the light transmission through multilayer graphene sheets that are spatially separated. By adopting the transfer matrix method modified for two-dimensional material, we find that the graphene multilayers manifest a broad passband in the transmission spectrum. The two edges of the passband are determined by the interband threshold of electron transition in graphene and the cutoff wavelength of Bloch mode in the multilayer structure. By varying the interlayer space of the graphene multilayers, the structure can be used to increase the phase velocity of normally incident light or to make the phase at rest like epsilon-near-zero material. The study shows that the graphene multilayers may find great applications in optical switches, filters, and phase modulators. (C) 2014 AIP Publishing LLC.