Application Of Graphene And Boron Nitride Based Metamaterial In High-resolution Hyperlens

The concept of hyperlens, as a novel transformation optics device, is a promising real-time super-resolution lens that can effectively transform evanescent waves into propagating waves and thus breaks the diffraction limit. So far, there are two different ways to realize hyperlens:one is the use of metal which has negative permittivity in optical frequency, another is the use of layered metallic and dielectric stack structure. However, due to the loss of metal, the efficiency of these design are not very high.2D material graphene and boron nitride owned lots of novel electrical and optical properties cause great research attention. In this paper, we have discussed the development and current situation of the diffraction limit and metamaterial. Meanwhile, we have also introduced the basic electrical and optical properties of graphene and boron nitride.This paper focuses on the hyperlens design based on graphene and boron nitride at ultraviolet frequency band.First of all, we have calculated the optical properties of graphene and boron nitride using the open source software SIESTA which is based on the first principle theory. Since the software just gives the imaginary part of dielectric constant of material, we need use the traditional electromagnetic wave theory Kramers-Kronig relations to get the real part of dielectric constant. The calculation results show that in ultraviolet band, both graphene and boron nitride have strong anisotropic properties which can be used in hyperlens design. The permittivity of graphene which is parallel to optical axis is positive while perpendicular is negative. At same time, the imaginary part of permittivity of graphene is relative small compared to metal at ultraviolet band, and therefore, it can make up for the disadvantage brought by metal, and realize real-time ultraviolet band high resolution imaging.Then, we have designed flat and cylindrical hyperlens based on graphene and boron nitride separately,utilizing their strong anisotropic properies at ultraviolet band. The simulation results in COMSOL MULTIPHYSICS showed that the hyperlens/superlens can really overcome the diffraction limit and imaging in the far filed.The parameter of graphene we choose is εz:=-3.817+4.265i and εx=2.229+0i at f=1200THz,and for boron nitride,we choose εz:=-1.637+1.839i and εz=2.277+0i at f=1400THz.