4,464 research outputs found
Nonlinear switching and solitons in PT-symmetric photonic systems
One of the challenges of the modern photonics is to develop all-optical
devices enabling increased speed and energy efficiency for transmitting and
processing information on an optical chip. It is believed that the recently
suggested Parity-Time (PT) symmetric photonic systems with alternating regions
of gain and loss can bring novel functionalities. In such systems, losses are
as important as gain and, depending on the structural parameters, gain
compensates losses. Generally, PT systems demonstrate nontrivial
non-conservative wave interactions and phase transitions, which can be employed
for signal filtering and switching, opening new prospects for active control of
light. In this review, we discuss a broad range of problems involving nonlinear
PT-symmetric photonic systems with an intensity-dependent refractive index.
Nonlinearity in such PT symmetric systems provides a basis for many effects
such as the formation of localized modes, nonlinearly-induced PT-symmetry
breaking, and all-optical switching. Nonlinear PT-symmetric systems can serve
as powerful building blocks for the development of novel photonic devices
targeting an active light control.Comment: 33 pages, 33 figure
Gap solitons and symmetry breaking in parity-time symmetric microring CROWs
The propagation properties of optical fields in linear and nonlinear
parity-time symmetric microring coupled resonator optical waveguides are
studied. The effects described include the existence of symmetry breaking
thresholds, the propagation of gap solitons in nonlinear transmission lines and
the existence of quasi stable propagation regimes outside the broken symmetry
regions.Comment: Final Versio
Self-trapping of light and nonlinear localized modes in 2D photonic crystals and waveguides
We overview our recent results on the nonlinear localized modes in
two-dimensional (2D) photonic crystals and photonic-crystal waveguides.
Employing the technique based on the Green function, we describe the existence
domains for nonlinear guided modes in photonic crystal waveguides and study
their unique properties including bistability. We also show that low-amplitude
nonlinear modes near the band edge of a reduced-symmetry 2D square-lattice
photonic crystals, which are usually unstable, can be stabilized due to
effective long-range linear and nonlinear interactions.Comment: 20 pages (LaTeX) with 12 figures (EPS
Bifurcations and stability of gap solitons in periodic potentials
We analyze the existence, stability, and internal modes of gap solitons in
nonlinear periodic systems described by the nonlinear Schrodinger equation with
a sinusoidal potential, such as photonic crystals, waveguide arrays,
optically-induced photonic lattices, and Bose-Einstein condensates loaded onto
an optical lattice. We study bifurcations of gap solitons from the band edges
of the Floquet-Bloch spectrum, and show that gap solitons can appear near all
lower or upper band edges of the spectrum, for focusing or defocusing
nonlinearity, respectively. We show that, in general, two types of gap solitons
can bifurcate from each band edge, and one of those two is always unstable. A
gap soliton corresponding to a given band edge is shown to possess a number of
internal modes that bifurcate from all band edges of the same polarity. We
demonstrate that stability of gap solitons is determined by location of the
internal modes with respect to the spectral bands of the inverted spectrum and,
when they overlap, complex eigenvalues give rise to oscillatory instabilities
of gap solitons.Comment: 18 pages, 11 figures; updated bibliograph
Band-gap solitons in nonlinear optically-induced lattices
We introduce novel optical solitons that consist of a periodic and a
spatially localized components coupled nonlinearly via cross-phase modulation.
The spatially localized optical field can be treated as a gap soliton supported
by the optically-induced nonlinear grating. We find different types of these
band-gap composite solitons and demonstrate their dynamical stability.Comment: 4 pages, 5 figure
- …