Biomedical Engineering Reference
In-Depth Information
lines in homogeneous media, can be focused by curved glasses, can
be reflected by smooth surfaces, and is refracted when crossing
interfaces between media with different density. Mankind has been
using these properties to transmit signals, detect, and exchange
information for centuries. The physical principles behind these
phenomena were established well before 1900 and are based
on structures and devices many wavelengths large. However,
due to recent advances in science and technology, scientists
and researchers have become more interested in controlling the
interactionoflightwithmatterinnanostructuresofsizecomparable
with the wavelength of operation. These possibilities can largely
overcome the conventional limitations of light manipulation and
theirapplications,mostlyassociatedwiththediffractionlimit.Ithas
been found, in particular, that nanoparticles and their collections
mayachieveexoticphenomenathatarenotavailableinconventional
optics. The whole research area of metamaterials, currently one of
themostpopularinoptics,hasemergedfromtheseconcepts[1-21].
Metamaterials are artificial materials composed of sub-
wavelength engineered inclusions, designed to collectively achieve
exotic electromagnetic properties at the frequency of interest,
beyond those available in nature or in any of their constituents.
Although technology and nanofabrication have evolved at a fast
pace and reached levels of flexibility that were unimaginable
even a few years ago, specific physical and engineering challenges
associated with design and realization of optical metamaterials
still remain unresolved. In particular, technological challenges limit
the realization of fully three-dimensional nanoscale metamaterials,
especially in the optical regime [14, 19, 22-27]; in addition,
the complex wave matter interaction in large arrays of resonant
nanostructures, often with exotic plasmonic properties [28-30],
requires parallel advances in the theoretical understanding and
modeling of these effects.
Different from metamaterials, metasurfaces or metafilms are
effectively the two-dimensional equivalent of metamaterials [31-
33]. The interest in their design, realization, and characterization
has grown in parallel with the interest in metamaterials, as it was
shown that, by tailoring their resonant constituent sub-wavelength
inclusions, they may provide analogous exotic electromagnetic
