Theoretical design of nano-layered Al/SiO2 metamaterial with hyperbolic dispersion with minimum losses

Abstract

Motivated by a greater need for increased performance in modern-day technology, this paper shows the results of theoretical calculations for the optical properties of Al/SiO2 nano-layered metamaterial with hyperbolic dispersion. Our main focus is on designing a metamaterial with low losses, since losses might outweigh any increase in speed of photonic devices. We have investigated the effect of three major variables (number/thickness of the Al layers and Al fill fraction) on inherent losses and hyperbolic dispersion using the effective medium approximation with non-local corrections. Our model predicts a variation of the dielectric permittivity only in the perpendicular direction as the number of Al layers changes. First, we present the results of the detailed study of varying the number of Al layers, N, in attempt to find the “saturation limit” of non-local corrections in Al/SiO2 layers. Next, we changed Al fill fraction in a sample of N= 20 layers to find parameters for the material with minimized losses. We found that both of these effects determine the transition wavelength to hyperbolic dispersion, which allows for fine-tuning of the optical properties for future applications.