Design, fabrication and characterization of indefinite metamaterials of nanowires

Abstract

Indefinite optical properties, which are typically characterized by hyperbolic dispersion relations, have not been observed in naturally occurring materials, but can be realized through a metamaterial approach. We present here the design, fabrication and characterization of nanowire metamaterials with indefinite permittivity, in which allangle negative refraction of light is observed. The bottom-up fabrication technique, which applies electrochemical plating of nanowires in porous alumina template, is developed and demonstrated in achieving uniform hyperbolic optical properties at a large scale. We developed techniques to improve the uniformity and to reduce the defect density in the sample. The non-magnetic design and the off-resonance operation of the nanowire metamaterials significantly reduce the energy loss of electromagnetic waves and make the broad-band negative refraction of light possible.

Design and fabrication of a large-area superhydrophobic metal surface with anti-icing properties engineered using a top-down approach

“…A heterogeneous surface with randomly generated micro-and nanostructures does not appear to result in optimal hydrophobicity, uniformity, or consistency over the entire surface [26,27]. Additionally, previous studies have focused on the fabrication and the evaluation of functional surfaces with relatively small areas, but large-area engineered surfaces are required for practical applications.…”

Metaphotonics: An emerging field with opportunities and challenges

“…Electrochemical plating of nanowires in porous alumina templates, was demonstrated to lead to metamaterials with uniform hyperbolic optical properties. 286 An approach using apertured silver films as elements of visible negative-index metamaterial 287 was also demonstrated. A template-assisted and self-assembled electrochemical deposition method was used to fabricate an asymmetric Ag-polyvinyl alcohol-Ag multilayer nanostructure that showed negative index in the wavelength range from 535 to 565 nm.…”

Steering and collimating ballistic electrons with amphoteric refraction

“…The same conclusion holds also for light: 11 in common, non-magnetic materials with principal axes normal to the interface amphoteric refraction occurs only if the effective permittivity along the x and y directions have opposite signs, but this situation can occur in carefully designed structures. [20][21][22] Amphoteric refraction of ballistic electrons can occur, however, when the principal coordinate axes of the effective mass tensor make an angle u with the x direction, so that the electron dispersion relation can be written as…”