511 research outputs found
Non-magnetic nano-composites for optical and infrared negative refraction index media
We develop an approach to use nanostructured plasmonic materials as a
non-magnetic negative-refractive index system at optical and near-infrared
frequencies. In contrast to conventional negative refraction materials, our
design does not require periodicity and thus is highly tolerant to fabrication
defects. Moreover, since the proposed materials are intrinsically non-magnetic,
their performance is not limited to proximity of a resonance so that the
resulting structure has relatively low loss. We develop the analytical
description of the relevant electromagnetic phenomena and justify our analytic
results via numerical solutions of Maxwell equations
Strongly anisotropic media: the THz perspectives of left-handed materials
We demonstrate that non-magnetic () left-handed materials can
be effectively used for waveguide imaging systems. We also propose a specific
THz realization of the non-magnetic left-handed material based on homogeneous,
naturally-occurring media
Negative Refractive Index in Optics of Metal-Dielectric Composites
Specially designed metal-dielectric composites can have a negative refractive
index in the optical range. Specifically, it is shown that arrays of single and
paired nanorods can provide such negative refraction. For pairs of metal rods,
a negative refractive index has been observed at 1.5 micrometer. The inverted
structure of paired voids in metal films may also exhibit a negative refractive
index. A similar effect can be accomplished with metal strips in which the
refractive index can reach -2. The refractive index retrieval procedure and the
critical role of light phases in determining the refractive index is discussed.Comment: 39 pages, 17 figures, 24 equation
Diffractive optics approach towards subwavelength pixels
Pixel size in cameras and other refractive imaging devices is typically
limited by the free-space diffraction. However, a vast majority of
semiconductor-based detectors are based on materials with substantially high
refractive index. We demonstrate that diffractive optics can be used to take
advantage of this high refractive index to reduce effective pixel size of the
sensors below free-space diffraction limit. At the same time, diffractive
systems encode both amplitude and phase information about the incoming beam
into multiple pixels, offering the platform for noise-tolerant imaging with
dynamical refocusing. We explore the opportunities opened by high index
diffractive optics to reduce sensor size and increase signal-to-noise ratio of
imaging structures.Comment: submitted to SPIE-DCS 201
Seismic emissions from a tide-water calving glacier (Bowdoin Glacier, Greenland)
GRENE北極気候変動研究事業研究成果報告会日時:2016年3月4日(金) 14:30-16:30 (Core time 14:.30-15:40)会場:国立国語研究所 2Fホワイ
Cut-wire-pair structures as two-dimensional magnetic metamaterials
We study numerically and experimentally magnetic metamaterials based on
cut-wire pairs instead of split-ring resonators. The cut-wire pair planar
structure is extended in order to create a truly two-dimensional metamaterial
suitable for scaling to optical frequencies. We fabricate the cut-wire
metamaterial operating at microwave frequencies with lattice spacing around 10%
of the free-space wavelength, and find good agreement with direct numerical
simulations. Unlike the structures based on split-ring resonators, the
nearest-neighbor coupling in cut-wire pairs can result in a magnetic stop-band
with propagation in the transverse direction
Negative effective permeability and left-handed materials at optical frequencies
We present here the design of nano-inclusions made of properly arranged
collections of plasmonic metallic nano-particles that may exhibit a resonant
magnetic dipole collective response in the visible domain. When such inclusions
are embedded in a host medium, they may provide metamaterials with negative
effective permeability at optical frequencies. We also show how the same
inclusions may provide resonant electric dipole response and, when combining
the two effects at the same frequencies, lefthanded materials with both
negative effective permittivity and permeability may be synthesized in the
optical domain with potential applications for imaging and nano-optics
applications.Comment: 11 pages, 6 figures; modified the format, added a figur
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