46 research outputs found
Vortex-vortex control in exciton-polariton condensates
Vortices are widely studied in fields ranging from nonlinear optics to
magnetic systems and superconductors. A vortex carries a binary information
corresponding to its topological charge, `plus' or `minus', that can be used
for information storage and processing. In spatially extended optical and
condensed many-particle systems, achieving full control over vortex formation
and its charge is particularly difficult and is not easily extended to systems
of multiple vortices. Here we demonstrate the optical creation of multiplets of
phase-locked vortices in polariton condensates using off-resonant excitation
with ring-shaped pump beams. We find that the vorticity of one vortex can be
controlled solely using the phase-locking with other nearby vortices. Using
this mechanism, we demonstrate how an existing vortex with a specific
topological charge can be inverted to the oppositely charged state, and how the
charge state of one reference vortex can be copied to a neighboring vortex.
This way we can optically encode any set of binary information onto a chain of
vortices. We further show that this information can be modified later by using
the possibility to address and manipulate each vortex in the chain
individually.Comment: Physical Review B, in pres
Circular polarization reversal of half-vortex cores in polariton condensates
Vortices are topological objects carrying quantized orbital angular momentum
and have been widely studied in many physical systems for their applicability
in information storage and processing. In systems with spin degree of freedom
the elementary excitations are so called half-vortices, carrying a quantum
rotation only in one of the two spin components. We study the spontaneous
formation and stability of localized such half-vortices in semiconductor
microcavity polariton condensates, non-resonantly excited by a linearly
polarized ring-shaped pump. The TE-TM splitting of optical modes in the
microcavity system leads to an effective spin-orbit coupling, resulting in
solutions with discrete rotational symmetry. The cross-interaction between
different spin components provides an efficient method to realize all-optical
half-vortex core switching inverting its circular polarization state. This
switching can be directly measured in the polarization resolved intensity in
the vortex core region and it can also be applied to higher order half-vortex
states.Comment: 8 pages, 8 figure
Multiple-type solutions for multipole interface solitons in thermal nonlinear media
We address the existence of multipole interface solitons in one-dimensional
thermal nonlinear media with a step in the linear refractive index at the
sample center. It is found that there exist two types of solutions for tripole
and quadrupole interface solitons. The two types of interface solitons have
different profiles, beam widths, mass centers, and stability regions. For a
given propagation constant, only one type of interface soliton is proved to be
stable, while the other type can also survive over a long distance. In
addition, three types of solutions for fifth-order interface solitons are
found.Comment: 5 pages, 5 figure