70 research outputs found
Soliton dynamics in symmetric and non-symmetric complex potentials
Soliton propagation dynamics under the presence of a complex potential are
investigated. A large variety of qualitatively different potentials, including
periodic, semi-infinite periodic and localized potentials, is considered. Cases
of both symmetric and non-symmetric potentials are studied in terms of their
effect on soliton dynamics. The rich set of dynamical features of soliton
propagation include dynamical trapping, periodic and non-periodic soliton mass
variation and non-reciprocal scattering dynamics. These features are
systematically investigated with the utilization of an effective particle phase
space approach which is shown in remarkable agreement with direct numerical
simulations. The generality of the results enables the consideration of
potential applications where the inhomogeneity of the gain and loss is
appropriately engineered in order to provide desirable soliton dynamics.Comment: 19 pages, 6 figures, Submitted for publication in Opt. Commun.
(17/7/2014
Spectral Signatures of Exceptional Points and Bifurcations in the Fundamental Active Photonic Dimer
The fundamental active photonic dimer consisting of two coupled quantum well
lasers is investigated in the context of the rate equation model. Spectral
transition properties and exceptional points are shown to occur under general
conditions, not restricted by PT-symmetry as in coupled mode models, suggesting
a paradigm shift in the field of non-Hermitian photonics. The optical spectral
signatures of system bifurcations and exceptional points are manifested in
terms of self-termination effects and observable drastic variations of the
spectral line shape that can be controlled in terms of optical detuning and
inhomogeneous pumping.Comment: 13 pages, 5 figure
The Asymmetric Active Coupler: Stable Nonlinear Supermodes and Directed Transport
We consider the asymmetric active coupler (AAC) consisting of two coupled
dissimilar waveguides with gain and loss. We show that under generic
conditions, not restricted by parity-time symmetry, there exist finite-power,
constant-intensity nonlinear supermodes (NS), resulting from the balance
between gain, loss, nonlinearity, coupling and dissimilarity. The system is
shown to possess nonreciprocal dynamics enabling directed power transport and
optical isolation functionality
Power and momentum dependent soliton dynamics in lattices with longitudinal modulation
Soliton dynamics in a large variety of longitudinally modulated lattices are
studied in terms of phase space analysis for an effective particle approach and
direct numerical simulations. Complex soliton dynamics are shown to depend
strongly on both their power/width and their initial momentum as well as on
lattice parameters. A rish set of qualitatively distinct dynamical features of
soliton propagation that have no counterpart in longitudinally uniform lattices
is illustrated. This set includes cases of enhanced soliton mobility, dynamical
switching, extended trapping in several transverse lattice periods, and
quasiperiodic trapping, which are promising for soliton control applications
The Asymmetric Active Coupler: Stable Nonlinear Supermodes and Directed Transport
We consider the asymmetric active coupler (AAC) consisting of two coupled dissimilar waveguides with gain and loss. We show that under generic conditions, not restricted by parity-time symmetry, there exist finite-power, constant-intensity nonlinear supermodes (NS), resulting from the balance between gain, loss, nonlinearity, coupling and dissimilarity. The system is shown to possess non-reciprocal dynamics enabling directed power transport functionality
Role of the edge electric field in the resonant mode-particle interactions and the formation of transport barriers in toroidal plasmas
The impact of an edge radial electric field on the particle orbits and the
orbital spectrum in an axisymmetric toroidal magnetic equilibrium is
investigated using a guiding center canonical formalism. Poloidal and
bounce/transit-averaged toroidal precession frequencies are calculated,
highlighting the role of the radial electric field. The radial electric field
is shown to drastically modify the resonance conditions between particles with
certain kinetic characteristics and specific perturbative non-axisymmetric
modes and to enable the formation of transport barriers. The locations of the
resonances and the transport barriers, that determine the particle, energy and
momentum transport are shown to be accurately pinpointed in the phase space, by
employing the calculated orbital frequencies.Comment: 23 pages, 8 figure
Time Crystals transforming Frequency Combs in Tunable Photonic Oscillators
The response of a tunable photonic oscillator, consisting of an Optically
Injected Semiconductor Laser, under an injected Frequency Comb is considered
with the utilization of the concept of the Time Crystal that has been widely
used for the study of driven nonlinear oscillators in the context of
mathematical biology. The dynamics of the original system reduce to a radically
simple one-dimensional circle map with properties and bifurcations determined
by the specific features of the Time Crystal fully describing the phase
response of the limit cycle oscillation. The circle map is shown to accurately
model the dynamics of the original nonlinear system of ordinary differential
equations and capable for providing conditions for resonant synchronization
resulting to output frequency combs with tunable shape characteristics. Such
theoretical developments can have potential for significant photonic signal
processing applications.Comment: 19 pages, 9 figure
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