Effect of size of aluminum/silicon dioxide/aluminum nanosandwich films on their optical properties

Abstract

Three aluminum (Al)/silicon dioxide (SiO2)/aluminum (Al) nanosandwich films (SWFs) of various heights were fabricated using glancing angle deposition. An SWF comprises a 45-nm thick SiO2layer sandwiched between two Al nanopillars. The thicknesses of both top and bottom nanopillars were varied from 187.5 to 217.5 nm. The equivalent constitutive and related parameters of each SWF were obtained from the reflection coefficients and transmission coefficients that were measured using a walk-off interferometer. Both the equivalent permittivity and the equivalent permeability of each SWF turned out to be negative real. Exactly how the height of the Al nanopillars of the double negative SWF affects its low reflectance through destructive interference is also examined using the wave tracing method. Moreover, the localized reversed magnetic field in the SiO2layer of each SWF was simulated by finite-difference timedomain method to qualitatively interpret the negative real permeability. © The Authors.