▎ 摘　　要

We propose a nanostructured hyperbolic metamaterial (HMM) that can make the transition between elliptic and hyperbolic regimes in the near infrared (IR) frequency range. This switchable HMM is a slab made of a periodic stack of metal/Al2O3/graphene/Al2O3/metal nano-layers. By tuning the graphene conductivity via tuning its chemical potential, through a variable external bias, the response of this highly anisotropic medium to a monochromatic TM incident light can be switched between a positive/negative refraction regime and a negative refraction/no-transmission regime. The proposed structure is suitable for applications such as beam splitters, modulators, four-port devices, and optical gates. (C) 2015 Optical Society of America