348 research outputs found
Lattice-supported surface solitons in nonlocal nonlinear media
We reveal that lattice interfaces imprinted in nonlocal nonlinear media
support surface solitons that do not exist in other similar settings, including
interfaces of local and nonlocal uniform materials. We show the impact of
nonlocality on the domains of existence and stability of the surface solitons,
focusing on new types of dipole solitons residing partially inside the optical
lattice. We find that such solitons feature strongly asymmetric shapes and that
they are stable in large parts of their existence domain.Comment: 13 pages, 3 figures, to appear in Optics Letter
Laser Induced Non-Sequential Double Ionization Investigated at and Below the Threshold for Electron Impact Ionization
We use correlated electron–ion momentum measurements to investigate laserinduced non-sequential double ionization of Ar and Ne. Light intensities are chosen in a regime at and below the threshold where, within the rescattering model, electron impact ionization of the singly charged ion core is expected to become energetically forbidden. Yet we find Ar2+ ion momentum distributions and an electron–electron momentum correlation indicative of direct impactionization. Within the quasistatic model this may be understood by assuming that the electric field of the light wave reduces the ionization potential of the singly charged ion core at the instant of scattering. The width of the projection of the ion momentum distribution onto an axis perpendicular to the light beam polarization vector is found to scalewiththe square root of the peak electric field strength in the light pulse. A scaling like this is not expected from the phase space available after electron impact ionization. It may indicate that the electric field at the instant of scattering is usually different fromzero and determines the transverse momentum distribution. A comparison of our experimental results with several theoretical results is give
Directional coupling and branching of optical signals by dark beams
ABSTRACT Various types of dark optical beams with respect to their phase dislocation are discussed and their propagation dynamics is analyzed. On the basis of numerical results 1D and 2D optical couplers are proposed. The respective energy efficiencies for each of the output channels are estimated. Multiple charged optical vortices and their topological instability are presented. Through a proper type of perturbation applied to these vortices they could be split into several sub-beams, thus giving the opportunity of proposing all-optical branching schemes. Two output channel distribution schemes for such an optical brancher are discussed
Modulational instability, solitons and beam propagation in spatially nonlocal nonlinear media
We present an overview of recent advances in the understanding of optical
beams in nonlinear media with a spatially nonlocal nonlinear response. We
discuss the impact of nonlocality on the modulational instability of plane
waves, the collapse of finite-size beams, and the formation and interaction of
spatial solitons.Comment: Review article, will be published in Journal of Optics B, special
issue on Optical Solitons, 6 figure
Observation of attraction between dark solitons
We demonstrate a dramatic change in the interaction forces between dark solitons in nonlocal nonlinear media. We present what we believe is the first experimental evidence of attraction of dark solitons. Our results indicate that attraction should be observable in other nonlocal systems, such as Bose-Einstein condensates with repulsive long-range interparticle interaction
Multipole vector solitons in nonlocal nonlinear media
We show that multipole solitons can be made stable via vectorial coupling in
bulk nonlocal nonlinear media. Such vector solitons are composed of mutually
incoherent nodeless and multipole components jointly inducing a nonlinear
refractive index profile. We found that stabilization of the otherwise highly
unstable multipoles occurs below a maximum energy flow. Such threshold is
determined by the nonlocality degree.Comment: 13 pages, 3 figures, to appear in Optics Letter
White light generated by femtosecond optical vortex beams
In this work we report detailed experimental and numerical investigation of the white light generation by singly and doubly charged optical vortices propagating in a Kerr medium, where spectral broadening and transfer of topological charge (TC) into emerging spectral satellites take place due to self-phase modulation and degenerate four-wave frequency mixing (FWFM). Experiments performed with different pump beams show excellent agreement with theory. Singly and doubly charged white light vortices are observed within more than ±200 nm bandwidth after nonlinear propagation in Argon gas. Our experiment and theory data confirm that the TC transformation of the newly generated spectral components follows a law analogous to the one for energy conservation in the FWFM process. We also present results on the white light vortex stability.</p
Trapped supercontinuum and multi-color gap solitons
We can now create structures to form solitons
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