261 research outputs found
Self-trapping and stable localized modes in nonlinear photonic crystals
We predict the existence of stable nonlinear localized modes near the band edge of a two-dimensional reduced-symmetry photonic crystal with a Kerr nonlinearity. Employing the technique based on the Green function, we reveal a physical mechanism of the mode stabilization associated with the effective nonlinear dispersion and long-range interaction in the photonic crystal
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
Low-threshold bistability of slow light in photonic-crystal waveguides
We analyze the resonant transmission of light through a
photonic-crystal waveguide side coupled to a Kerr nonlinear cavity, and
demonstrate how to design the structure geometry for achieving bistability
and all-optical switching at ultralow powers in the slow-light regime. We
show that the resonance quality factor in such structures scales inversely
proportional to the group velocity of light at the resonant frequency
and thus grows indefinitely in the slow-light regime. Accordingly, the
power threshold required for all-optical switching in such structures scales
as a square of the group velocity, rapidly vanishing in the slow-light regime
All-optical switching, bistability, and slow-light transmission in photonic crystal waveguide-resonator structures
We analyze the resonant linear and nonlinear transmission through a photonic crystal waveguide sidecoupled
to a Kerr-nonlinear photonic crystal resonator. First, we extend the standard coupled-mode theory
analysis to photonic crystal structures and obtain explicit analytical expressions for the bistability thresholds
and transmission coefficients which provide the basis for a detailed understanding of the possibilities associated
with these structures. Next, we discuss limitations of standard coupled-mode theory and present an
alternative analytical approach based on the effective discrete equations derived using a Green’s function
method. We find that the discrete nature of the photonic crystal waveguides allows a geometry-driven enhancement
of nonlinear effects by shifting the resonator location relative to the waveguide, thus providing an
additional control of resonant waveguide transmission and Fano resonances. We further demonstrate that this
enhancement may result in the lowering of the bistability threshold and switching power of nonlinear devices
by several orders of magnitude. Finally, we show that employing such enhancements is of paramount importance
for the design of all-optical devices based on slow-light photonic crystal waveguides
Curvature-induced symmetry breaking in nonlinear Schrodinger models
We consider a curved chain of nonlinear oscillators and show that the
interplay of curvature and nonlinearity leads to a symmetry breaking when an
asymmetric stationary state becomes energetically more favorable than a
symmetric stationary state. We show that the energy of localized states
decreases with increasing curvature, i.e. bending is a trap for nonlinear
excitations. A violation of the Vakhitov-Kolokolov stability criterium is found
in the case where the instability is due to the softening of the Peierls
internal mode.Comment: 4 pages (LaTex) with 6 figures (EPS
Low-threshold bistability of slow light in photonic-crystal waveguides
We analyze the resonant transmission of light through a photonic-crystal
waveguide side coupled to a Kerr nonlinear cavity, and demonstrate how to
design the structure geometry for achieving bistability and all-optical
switching at ultra-low powers in the slow-light regime. We show that the
resonance quality factor in such structures scales inversely proportional to
the group velocity of light at the resonant frequency and thus grows
indefinitely in the slow-light regime. Accordingly, the power threshold
required for all-optical switching in such structures scales as a square of the
group velocity, rapidly vanishing in the slow-light regime.Comment: LaTeX, 6 pages, 4 figure
Solitons in anharmonic chains with ultra-long-range interatomic interactions
We study the influence of long-range interatomic interactions on the
properties of supersonic pulse solitons in anharmonic chains. We show that in
the case of ultra-long-range (e.g., screened Coulomb) interactions three
different types of pulse solitons coexist in a certain velocity interval: one
type is unstable but the two others are stable. The high-energy stable soliton
is broad and can be described in the quasicontinuum approximation. But the
low-energy stable soliton consists of two components, short-range and
long-range ones, and can be considered as a bound state of these components.Comment: 4 pages (LaTeX), 5 figures (Postscript); submitted to Phys. Rev.
Coupled-resonator-induced reflection in photonic-crystal waveguide structures
We study the resonant transmission of light in a coupled-resonator optical
waveguide interacting with two nearly identical side cavities. We reveal and
describe a novel effect of the coupled-resonator-induced reflection (CRIR)
characterized by a very high and easily tunable quality factor of the
reflection line, for the case of the inter-site coupling between the cavities
and the waveguide. This effect differs sharply from the
coupled-resonator-induced transparency (CRIT) -- an all-optical analogue of the
electromagnetically-induced transparency -- which has recently been studied
theoretically and observed experimentally for the structures based on
micro-ring resonators and photonic crystal cavities. Both CRIR and CRIT effects
have the same physical origin which can be attributed to the Fano-Feshbach
resonances in the systems exhibiting more than one resonance. We discuss the
applicability of the novel CRIR effect to the control of the slow-light
propagation and low-threshold all-optical switching.Comment: LaTeX, 11 pages, 5 figure
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