972 research outputs found
Nonparaxial shape-preserving Airy beams with Bessel signature
Spatially accelerating beams that are solutions to the Maxwell equations may
propagate along incomplete circular trajectories, after which diffraction
broadening takes over and the beams spread out. Taking these truncated Bessel
wave fields to the paraxial limit, some authors sustained that it is recovered
the known Airy beams (AiBs). Based on the angular spectrum representation of
optical fields, we demonstrated that the paraxial approximation rigorously
leads to off-axis focused beams instead of finite-energy AiBs. The latter will
arise under the umbrella of a nonparaxial approach following elliptical
trajectories in place of parabolas. Deviations from full-wave simulations
appear more severely in beam positioning rather than its local profile
Radio Continuum Sources Associated with AB Aur
We present high angular resolution, high-sensitivity Very Large Array
observations at 3.6 cm of the Herbig Ae star AB Aur. This star is of interest
since its circumstellar disk exhibits characteristics that have been attributed
to the presence of an undetected low mass companion or giant gas planet. Our
image confirms the continuum emission known to exist in association with the
star, and detects a faint protuberance that extends about to its
SE. Previous theoretical considerations and observational results are
consistent with the presence of a companion to AB Aur with the separation and
position angle derived from our radio data. We also determine the proper motion
of AB Aur by comparing our new observations with data taken about 17 years ago
and find values consistent with those found by Hipparcos.Comment: 6 pages, 1 figur
Light capsules shaped by curvilinear meta-surfaces
We propose a simple yet efficient method for generating in-plane hollow beams
with a nearly-full circular light shell without the contribution of backward
propagating waves. The method relies on modulating the phase in the near field
of a centro-symmetric optical wavefront, such as that from a
high-numericalaperture focused wave field. We illustrate how beam acceleration
may be carried out by using an ultranarrow non-flat meta-surface formed by
engineered plasmonic nanoslits. A mirrorsymmetric, with respect to the optical
axis, circular caustic surface is numerically demonstrated that can be used as
an optical bottle
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