27 research outputs found

    A new criterion for the existence of KdV solitons in ferromagnets

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    The long-time evolution of the KdV-type solitons propagating in ferromagnetic materials is considered trough a multi-time formalism, it is governed by all equations of the KdV Hierarchy. The scaling coefficients of the higher order time variables are explicitly computed in terms of the physical parameters, showing that the KdV asymptotic is valid only when the angle between the propagation direction and the external magnetic field is large enough. The one-soliton solution of the KdV hierarchy is written down in terms of the physical parameters. A maximum value of the soliton parameter is determined, above which the perturbative approach is not valid. Below this value, the KdV soliton conserves its properties during an infinite propagation time

    Building patterns by traveling vortices and dipoles in periodic dissipative media

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    We analyze pattern-formation scenarios in the two-dimensional (2D) complex Ginzburg-Landau (CGL) equation with the cubic-quintic (CQ) nonlinearity and a cellular potential. The equation models laser cavities with built-in gratings, which are used to stabilize 2D patterns. The pattern-building process is initiated by kicking a localized compound mode, in the form of a dipole, quadrupole, or vortex which is composed of four local peaks. The hopping motion of the kicked mode through the cellular structure leads to the generation of various extended patterns pinned by the structure. In the ring-shaped system, the persisting freely moving dipole hits the stationary pattern from the opposite side, giving rise to several dynamical regimes, with the pinned multi-soliton chain playing the role of the Newton's cradle (NC)

    Stability calculations for the ytterbium-doped fiber laser passively mode-locked through nonlinear polarization rotation

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    We investigate theoretically a fiber laser passively mode-locked with nonlinear polarization rotation. A unidirectional ring cavity is considered with a polarizer placed between two sets of a halfwave plate and a quarterwave plate. A master equation is derived and the stability of the continuous and mode-locked solutions is studied. In particular, the effect of the orientation of the four phase plates and of the polarizer on the mode-locking regime is investigated

    In Vivo Diffuse Optical Tomography and Fluorescence Molecular Tomography

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    Photonic radio frequency down-converter based on parallel electro-absorption modulators in Ku/Ku band for space applications

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    International audienceIn this paper, we present a new photonic RF frequency down-convertor based on parallel electro-absorption modulators, and fiber Bragg grating filters, with reduced output spurious: only the converted IF signal and first three LO harmonics are present in the output spectrum. We give device performance in terms of conversion gain, noise factor, RF/IF and LO/IF isolations, carrier to third order intermodulation ratio (C/I3) and spectral purity. We also proof that it can work properly in the entire Ku band without a significant variation of performance
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