Search results for "Pattern"
showing 10 items of 4203 documents
Self-Optimising Breather Ultrafast Fibre Laser
2021
We demonstrate the self-optimisation of the breather regime in an ultrafast fibre laser through an evolutionary algorithm. Depending on the specified merit function, single breathers with controllable breathing ratio and period, and breather molecular complexes with a controllable number of constituents can be obtained.
Nonlinear dynamics of modulated signals in optical fibers
2012
International audience; The nonlinear Schrodinger equation (NLSE) describes the nonlinear waves localization dynamics in weakly dispersive media, and it has been extensively studied in various contexts in nonlinear science. A particular class of solutions of the NLSE that has recently attracted considerable attention is that of the solitons on finite background as their localization dynamics have been proposed as an important mechanism underlying the formation of extreme amplitude waves on the surface of the ocean. Much of this work has also been motivated by an extensive parallel research effort research in optics that has shown how nonlinear optical fiber systems can be used to implement …
Optical Peregrine soliton generation in standard telecommunications fiber
2011
International audience; We present detailled experimental and numerical results showing the generation and breakup of the optical Peregrine soliton in standard telecommunications fiber. The impact of non-ideal initial conditions is studied through direct cut back measurements of the longitudinal evolution of the emerging soliton dynamics, and is shown to be associated with the splitting of the Peregrine soliton into two subpulses.
Extreme events in nature, randomness and rogue wave in optics
2012
International audience; Recent work in nonlinear fiber optics has demonstrated qualitative and quantitative links between instabilities in optical propagation and the giant destructive rogue or freak waves on the surface of the ocean. The analogy between the appearance of instabilities in optics and the rogue waves on the oceanic surface is both intriguing and attractive, as it opens up possibilities to explore the extreme value dynamics in a convenient benchtop optical environment. The purpose of this talk will be to discuss the results that have been obtained in optics, and to consider both the similarities and the differences with oceanic rogue wave counterparts. The talk will review exp…
Optical bullets and "rockets" in nonlinear dissipative systems and their transformations and interactions
2006
We demonstrate the existence of stable optical light bullets in nonlinear dissipative media for both cases of normal and anomalous chromatic dispersion. The prediction is based on direct numerical simulations of the (3+1)-dimensional complex cubic-quintic GinzburgLandau equation. We do not impose conditions of spherical or cylindrical symmetry. Regions of existence of stable bullets are determined in the parameter space. Beyond the domain of parameters where stable bullets are found, unstable bullets can be transformed into >rockets> i.e. bullets elongated in the temporal domain. A few examples of the interaction between two optical bullets are considered using spatial and temporal interact…
Universal soliton pattern formations in passively mode-locked fiber lasers
2011
International audience; We investigate multiple-soliton pattern formations in a figure-of-eight passively mode-locked fiber laser. Operation in the anomalous dispersion regime with a double-clad fiber amplifier allows generation of up to several hundreds of solitons per round trip. We report the observation of remarkable soliton distributions: soliton gas, soliton liquid, soliton polycrystal, and soliton crystal, thus indicating the universality of such complexes.
18 parameter deformations of the Peregrine breather of order 10 solutions of the NLS equation
2015
We present here new solutions of the focusing one-dimensional nonlinear Schrödinger (NLS) equation which appear as deformations of the Peregrine breather of order 10 with 18 real parameters. With this method, we obtain new families of quasi-rational solutions of the NLS equation, and we obtain explicit quotients of polynomial of degree 110 in x and t by a product of an exponential depending on t. We construct new patterns of different types of rogue waves and recover the triangular configurations as well as rings and concentric rings as found for the lower-orders.
Rational solutions to the mKdV equation associated to particular polynomials
2021
International audience; Rational solutions to the modified Korteweg-de Vries (mKdV) equation are given in terms of a quotient of determinants involving certain particular polynomials. This gives a very efficient method to construct solutions. We construct very easily explicit expressions of these rational solutions for the first orders n = 1 until 10.
Alien flora of Europe: Species diversity, temporal trends, geographical patterns and research needs
2008
International audience; The paper provides the first estimate of the composition and structure of alien plants occurring in the wild in the European continent, based on the results of the DAISIE project (2004–2008), funded by the 6th Framework Programme of the European Union and aimed at “creating an inventory of invasive species that threaten European terrestrial, freshwater and marine environments”. The plant section of the DAISIE database is based on national checklists from 48 European countries/regions and Israel; for many of them the data were compiled during the project and for some countries DAISIE collected the first comprehensive checklists of alien species, based on primary data …
Simulateur de pulvérisation localisée d’herbicide
2019
Site-specific spraying is a technological lever to reduce the herbicide amount used in the case of chemical control of weeds. At the present time, detection and control technologies are available to apply herbicide only where weeds are present and thus provide an alternative to homogeneous application of chemicals on the entire surface of the field. In order to assess this practice, a digital simulator has been developed combining virtual infestation maps with different theoretical sprayer configurations. Simulations were used to localize herbicide applications and quantify herbicide reduction based on the spatial distribution of weeds and the width of independent spray units (boom sections…