226 research outputs found
Omnidirectionally Bending to the Normal in epsilon-near-Zero Metamaterials
Contrary to conventional wisdom that light bends away from the normal at the
interface when it passes from high to low refractive index media, here we
demonstrate an exotic phenomenon that the direction of electromagnetic power
bends towards the normal when light is incident from arbitrary high refractive
index medium to \epsilon-near-zero metamaterial. Moreover, the direction of the
transmitted beam is close to the normal for all angles of incidence. In other
words, the electromagnetic power coming from different directions in air or
arbitrary high refractive index medium can be redirected to the direction
almost parallel to the normal upon entering the \epsilon-near-zero
metamaterial. This phenomenon is counterintuitive to the behavior described by
conventional Snell's law and resulted from the interplay between
\epsilon-near-zero and material loss. This property has potential applications
in communications to increase acceptance angle and energy delivery without
using optical lenses and mechanical gimbals
Resonant Transmission of Electromagnetic Fields through Subwavelength Zero- Slits
We theoretically investigate the transmission of electromagnetic radiation
through a metal plate with a zero- metamaterial slit, where the
permittivity tends towards zero over a given bandwidth. Our analytic results
demonstrate that the transmission coefficient can be substantial for a broad
range of slit geometries, including subwavelength widths that are many
wavelengths long. This novel resonant effect has features quite unlike the
Fabry-P\'{e}rot-like resonances that have been observed in conductors with deep
channels. We further reveal that these high impedance ultranarrow
zero- channels can have significantly {\it greater} transmission
compared to slits with no wave impedance difference across them
Transparent photonic band in metallodielectric nanostructures
Under certain conditions, a transparent photonic band can be designed into a
one-dimensional metallodielectric nanofilm structure. Unlike conventional pass
bands in photonic crystals, where the finite thickness of the structure affects
the transmission of electromagnetic fields having frequency within the pass
band, the properties of the transparent band are almost unaffected by the
finite thickness of the structure. In other words, an incident field at a
frequency within the transparent band exhibits 100% transmission independent of
the number of periods of the structure. The transparent photonic band
corresponds to excitation of pure eigenstate modes across the entire Bloch band
in structures possessing mirror symmetry. The conditions to create these modes
and thereby to lead to a totally transparent band phenomenon are discussed.Comment: To be published in Phys. Rev.
Subwavelength fractional Talbot effect in layered heterostructures of composite metamaterials
We demonstrate that under certain conditions, fractional Talbot revivals can
occur in heterostructures of composite metamaterials, such as multilayer
positive and negative index media, metallodielectric stacks, and
one-dimensional dielectric photonic crystals. Most importantly, without using
the paraxial approximation we obtain Talbot images for the feature sizes of
transverse patterns smaller than the illumination wavelength. A general
expression for the Talbot distance in such structures is derived, and the
conditions favorable for observing Talbot effects in layered heterostructures
is discussed.Comment: To be published in Phys. Rev.
Perfect Absorption in Ultrathin Epsilon-Near-Zero Metamaterials Induced by Fast-Wave Non-Radiative Modes
Above-light-line surface plasmon polaritons can arise at the interface
between a metal and epsilon-near-zero metamaterial. This unique feature induces
unusual fast-wave non-radiative modes in a epsilon-near-zero material/metal
bilayer. Excitation of this peculiar mode leads to wide-angle perfect
absorption in low-loss ultrathin metamaterials. The ratio of the perfect
absorption wavelength to the thickness of the epsilon-near-zero metamaterial
can be as high as 10^4; the electromagnetic energy can be confined in a layer
as thin as {\lambda}/10000. Unlike conventional fast-wave leaky modes, these
fast-wave non-radiative modes have quasi-static capacitive features that
naturally match with the space-wave field, and thus are easily accessible from
free space. The perfect absorption wavelength can be tuned from mid- to
far-infrared by tuning the epsilon = 0 wavelength while keeping the thickness
of the structure unchanged
Classifying motion states of AUV based on graph representation for multivariate time series
Acknowledgement This work is supported by Natural Science Foundation of Shandong Province (ZR2020MF079) and China Scholarship Council (CSC).Peer reviewedPostprin
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