1,745 research outputs found
Pedestal free pulse compression of chirped optical solitons
Peer reviewedPostprin
On integrability of the Yao-Zeng two-component short-pulse equation
We show how the Yao-Zeng system of coupled short-pulse equations is related
to the original short-pulse equation and obtain the correct zero-curvature
representation of the Yao-Zeng system via this relationship.Comment: 5 page
Optical polarization rogue waves from supercontinuum generation in zero dispersion fiber pumped by dissipative soliton
Optical rogue waves emerge in nonlinear optical systems with extremely large amplitudes, and leave without a trace. In this work, we reveal the emergence of optical polarization rogue waves in supercontinuum generation from a zero-dispersion fiber, pumped by a dissipative soliton laser. Flat spectral broadening is achieved by modulation instability, followed by cascaded four-wave-mixing. In this process, we identify the emergence of optical polarization rogue waves, based on the probability density function of the relative distance among polarization states. Experimental results show that optical polarization rogue waves originate from vector multi-wave-mixing. Besides, we observe double peaks, and even triple peaks in the histogram of the state of polarization. This is a new and intriguing property, never observed so far in optical rogue waves, for example those emerging in the statistics of pulse intensities. Our polarization domain statistical analysis provides a new insight into the still debated topic of the mechanism for rogue wave generation in optical supercontinuum
Nonlinear atom optics and bright gap soliton generation in finite optical lattices
We theoretically investigate the transmission dynamics of coherent matter
wave pulses across finite optical lattices in both the linear and the nonlinear
regimes. The shape and the intensity of the transmitted pulse are found to
strongly depend on the parameters of the incident pulse, in particular its
velocity and density: a clear physical picture for the main features observed
in the numerical simulations is given in terms of the atomic band dispersion in
the periodic potential of the optical lattice. Signatures of nonlinear effects
due the atom-atom interaction are discussed in detail, such as atom optical
limiting and atom optical bistability. For positive scattering lengths, matter
waves propagating close to the top of the valence band are shown to be subject
to modulational instability. A new scheme for the experimental generation of
narrow bright gap solitons from a wide Bose-Einstein condensate is proposed:
the modulational instability is seeded in a controlled way starting from the
strongly modulated density profile of a standing matter wave and the solitonic
nature of the generated pulses is checked from their shape and their
collisional properties
Exterior complex scaling as a perfect absorber in time-dependent problems
It is shown that exterior complex scaling provides for complete absorption of
outgoing flux in numerical solutions of the time-dependent Schr\"odinger
equation with strong infrared fields. This is demonstrated by computing high
harmonic spectra and wave-function overlaps with the exact solution for a
one-dimensional model system and by three-dimensional calculations for the H
atom and a Ne atom model. We lay out the key ingredients for correct
implementation and identify criteria for efficient discretization
Phase retrieval via regularization in self-diffraction based spectral interferometry
A novel variant of spectral phase interferometry for direct electric-field
reconstruction (SPIDER) is introduced and experimentally demonstrated. Other
than most previously demonstrated variants of SPIDER, our method is based on a
third-order nonlinear optical effect, namely self-diffraction, rather than the
second-order effect of sum-frequency generation. On one hand, self-diffraction
(SD) substantially simplifies phase-matching capabilities for multi-octave
spectra that cannot be hosted by second-order processes, given manufacturing
limitations of crystal lengths in the few-micrometer range. On the other hand,
however, SD SPIDER imposes an additional constraint as it effectively measures
the spectral phase of a self-convolved spectrum rather than immediately
measuring the fundamental phase. Reconstruction of the latter from the measured
phase and the spectral amplitude of the fundamental turns out to be an
ill-posed problem, which we address by a regularization approach. We discuss
the numerical implementation in detail and apply it to measured data from a
Ti:sapphire amplifier system. Our experimental demonstration used 40-fs pulses
and a 500 m thick BaF crystal to show that the SD SPIDER signal is
sufficiently strong to be separable from stray light. Extrapolating these
measurements to the thinnest conceivable nonlinear media, we predict that
bandwidths well above two optical octaves can be measured by a suitably adapted
SD SPIDER apparatus, enabling the direct characterization of pulses down to
single-femtosecond pulse durations. Such characteristics appear out of range
for any currently established pulse measurement technique
From modulational instability to focusing dam breaks in water waves
We report water wave experiments performed in a long tank where we consider the evolution of nonlinear deep-water surface gravity waves with the envelope in the form of a large-scale rectangular barrier. Our experiments reveal that, for a range of initial parameters, the nonlinear wave packet is not disintegrated by the Benjamin-Feir instability but exhibits a specific, strongly nonlinear modulation, which propagates from the edges of the wavepacket towards the center with finite speed. Using numerical tools of nonlinear spectral analysis of experimental data we identify the observed envelope wave structures with focusing dispersive dam break flows, a peculiar type of dispersive shock waves recently described in the framework of the semi-classical limit of the 1D focusing nonlinear Schr"odinger equation (1D-NLSE). Our experimental results are shown to be in a good quantitative agreement with the predictions of the semi-classical 1D-NLSE theory. This is the first observation of the persisting dispersive shock wave dynamics in a modulationally unstable water wave system
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