583 research outputs found
Second-harmonic generation in nonlinear left-handed metamaterials
We study the second-harmonic generation in left-handed metamaterials with a
quadratic nonlinear response. We demonstrate a novel type of the exact phase
matching between the backward propagating wave of the fundamental frequency and
the forward propagating wave of the second harmonics. We show that this novel
parametric process can convert a surface of the left-handed metamaterial into
an effective mirror totally reflecting the second harmonics generated by an
incident wave. We derive and analyze theoretically the coupled-mode equations
for a semi-infinite nonlinear metamaterial. We also study numerically the
second-harmonic generation by a metamaterial slab of a finite thickness, and
reveal the existence of multistable nonlinear effects.Comment: 6 pages, 6 figure
Giant Goos-Hanchen effect at the reflection from left-handed metamaterials
We study the beam reflection from a layered structure with a left-handed
metamaterial. We predict a giant lateral (Goos-Hanchen) shift and splitting of
the beam due to the resonant excitation of surface polaritons with a
vortex-like energy flow between the right- and left-handed materials
Microarcsecond instability of the celestial reference frame
The fluctuation of the angular positions of reference extragalactic radio and
optical sources under the influence of the irregular gravitational field of
visible Galactic stars is considered. It is shown that these angular
fluctuations range from a few up to hundreds of microarcseconds. This leads to
a small rotation of the celestial reference frame. The nondiagonal coefficients
of the rotation matrix are of the order of a microarcsecond. The temporal
variation of these coefficients due to the proper motion of the foreground
stars is of the order of one microsecond per 20 years. Therefore, the celestial
reference frame can be considered inertial and homogeneous only to
microarcsecond accuracy. Astrometric catalogues with microarcsecond accuracy
will be unstable, and must be reestablished every 20 years.Comment: 5 pages, 2 figures, accepted to MNRA
The parallax distorsion via a weak microlensing effect
Parallax measurements allow distances to celestial objects to be determined.
Coupled with measurement of their position on the celestial sphere, it gives a
full three-dimensional picture of the location of the objects relative to the
observer. The distortion of the parallax value of a remote source affected by a
weak microlensing is considered. This means that the weak microlensing leads to
distortion of the distance scale. It is shown that the distortions to appear
may change strongly the parallax values in case they amount to several
microseconds of arc. In particular, at this accuracy many measured values of
the parallaxes must be negative.Comment: 34 LaTeX pages, 12 PostScript figure (epsfig.sty
Giant Goos-Hanchen effect at the reflection from left-handed metamaterials
We study the beam reflection from a layered structure with a left-handed
metamaterial. We predict a giant lateral (Goos-Hanchen) shift and splitting of
the beam due to the resonant excitation of surface polaritons with a
vortex-like energy flow between the right- and left-handed materials.Comment: 3 pages, 3 figure
Transmission properties of left-handed band-gap structures
We analyze transmission of electromagnetic waves through a periodic band-gap
structure consisting of slabs of a left-handed metamaterial and air. Using the
effective parameters of the metamaterial derived from its microscopic
structure, we study, with the help of the transfer-matrix approach and by means
of the finite-difference-time-domain numerical simulations, the transmission
properties of such a left-handed photonic crystals in a novel type of band gap
associated with the zero averaged refractive index. We demonstrate that the
transmission can be made tunable by introducing defects, which allow to access
selectively two different types of band gaps.Comment: 5 pages, 8 figure
Subwavelength imaging with opaque left-handed nonlinear lens
We introduce the concept of subwavelength imaging with an opaque nonlinear
left-handed lens by generating the second-harmonic field. We consider a slab of
composite left-handed metamaterial with quadratic nonlinear response and show
that such a flat lens can form, under certain conditions, an image of the
second-harmonic field of the source being opaque at the fundamental frequency.Comment: 3 pages, 3 figure
Nonlinear left-handed metamaterials
We analyze nonlinear properties of microstructured materials with negative
refraction, the so-called left-handed metamaterials. We demonstrate that the
hysteresis-type dependence of the magnetic permeability on the field intensity
allows changing the material properties from left- to right-handed and back.
Using the finite-difference time-domain simulations, we study wave transmission
through the slab of nonlinear left-handed material, and predict existence of
temporal solitons in such materials. We demonstrate also that nonlinear
left-handed metamaterials can support both TE- and TM-polarized self-trapped
localized beams, spatial electromagnetic solitons. Such solitons appear as
single- and multi-hump beams, being either symmetric or antisymmetric, and they
can exist due to the hysteresis-type magnetic nonlinearity and the effective
domains of negative magnetic permeability.Comment: 7 pages, 8 figure
Birefringent left-handed metamaterials and perfect lenses
We describe the properties of birefringent left-handed metamaterials and
introduce the concept of a birefringent perfect lens. We demonstrate that, in a
sharp contrast to the conventional left-handed perfect lens at
, where is the dielectric constant and is the
magnetic permeability, the birefringent left-handed lens can focus either TE or
TM polarized waves or both of them, allowing a spatial separation of the TE and
TM images. We discuss several applications of the birefringent left-handed
lenses such as the beam splitting and near-field diagnostics at the
sub-wavelength scale.Comment: 4 pages 6 figure
Chaos and rectification of electromagnetic wave in a lateral semiconductor superlattice
We find the conditions for a rectification of electromagnetic wave in a
lateral semiconductor superlattice with a high mobility of electrons. The
rectification is assisted by a transition to a dissipative chaos at a very high
mobility. We show that mechanism responsible for the rectification is a
creation of warm electrons in the superlattice miniband caused by an interplay
of the effects of nonlinearity and finite band width.Comment: 4 pages, 4 figures (2 color figs). Sufficient revision in comparison
with version1: More explanations on physics of the effect are added. Removed
from version1 material will be published elsewher
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