Abstract
Three aluminum (Al)/silicon dioxide ðSiO2Þ∕aluminum (Al) nanosandwich films (SWFs) of various heights were fabricated using glancing angle deposition. An SWF comprises a 45-nm thick SiO2 layer 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 SiO2 layer of each SWF was simulated by finite-difference time- domain method to qualitatively interpret the negative real permeability. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10
Highlights
With the rapid development of metamaterials in the recent decade, related works have demonstrated the novel optical properties of subwavelength structures of such metamaterials, including the negative refractive index1–3—from microwave wavelengths to visible wavelengths
Measurement results indicate that the polarization-dependent refractive index is positive real for s-polarization and negative real for p-polarization
The thicknessdependent optical parameters will be useful in optical thin film design for a novel optical filter that contains both positive and negative index thin films
Summary
With the rapid development of metamaterials in the recent decade, related works have demonstrated the novel optical properties of subwavelength structures of such metamaterials, including the negative refractive index1–3—from microwave wavelengths to visible wavelengths. Loss of the sandwiched film is sufficiently low to allow light to propagate through and to be reflected back from, the film, subsequently producing interference effect. Three samples with Al nanopillar thicknesses varying from 187.5 to 217.5 nm are fabricated Their electromagnetic parameters, including permittivity, permeability, and the bianisotropic parameter, are derived from optical parameters, including refractive index, forward impedance, and backward impedance. The low reflectance values for different thicknesses of nanosandwich films (SWFs) are analyzed using the optical parameters. This work reveals that low reflectivity exists over an extended range of thickness of SWF with negative real index. The thicknessdependent optical parameters will be useful in optical thin film design for a novel optical filter that contains both positive and negative index thin films
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
