Investigation of surface roughness influence on hyperbolic metamaterial performance

Abstract

Light scattering on rough surface with nano-sized features needs simulation with rigorous electromagnetic solver. The performance of such grid method as FDTD is closely connected with mesh size of computational domain and curvilinear surface approximation. The main goal of this work was to introduce simple model of surface roughness which does not involve objects with complicated shapes and could help to reduce computational costs. We described and proved numerically that the influence of surface roughness at the interfaces in metal-dielectric composite materials could be described by proper selection of refractive index of dielectric layers. Our calculations show that this model works for roughness with RMS value about 1 nm and below. Some examples of roughness realization with narrow spatial spectrum and high LER value could not be described properly by simple dielectric index modification, thus forming the limits of this simple roughness model applicability.