▎ 摘　　要

One of the unique characteristics of hyperbolic metamaterials (MMs) is the possibility of accessing various regimes of extreme anisotropy. Here, we propose a MM based on periodic layers of hafnium oxide (HfO2) and monolayer graphene. Based on the fact that graphene permittivity can be controlled by changing its chemical potential via externally applied electric voltage, we theoretically investigate the anisotropic behavior of the proposed MM as the function of the external electrical bias. Based on our findings, we provide examples of possible nanophotonic device applications based on such tunable hyperbolic MMs. Prototypes of a polarizer, a modulator, and a MM-assisted tunable coupler are investigated at the 1550 nm communication wavelength. Additionally, we show that the high tuning efficiency of MMs allows a miniaturized device to be realized with enhanced functionality per area for photonic integration. (C) 2018 Optical Society of America.