Search results for "Linear system"

On the correlation between phase-locking modes and Vibrational Resonance in a neuronal model

2018

International audience; We numerically and experimentally investigate the underlying mechanism leading to multiple resonances in the FitzHugh-Nagumo model driven by a bichromatic excitation. Using a FitzHugh-Nagumo circuit, we first analyze the number of spikes triggered by the system in response to a single sinusoidal wave forcing. We build an encoding diagram where different phase-locking modes are identified according to the amplitude and frequency of the sinusoidal excitation. Next, we consider the bichromatic driving which consists in a low frequency sinusoidal wave perturbed by an additive high frequency signal. Beside the classical Vibrational Resonance phenomenon, we show in real ex…

Nonlinear radiation imprisonment in magneto-optical vapor traps

2008

We analyze nonlinear radiation imprisonment (RI) effects in an optically thick vapor in different temperature regimes. An analytical approach is proposed to treat nonlinear decay problems. Special attention is paid to vapor samples having curvilinear geometries (cylinder, sphere) and being excited by a strong laser pulse. We derive a number of new formulas for different radiative trapping factors as functions of opacity and propose a general approach for RI evaluation allowing us to deal with samples both at room and low, or very low, temperatures, such as those customarily achieved in magneto-optical trap (MOT) experiments. As a result, we predict a "subnatural" decay of radiation escaping…

Complete characterization of terahertz pulse trains generated from nonlinear processes in optical fibers

2001

The measurement technique of frequency-resolved optical gating (FROG) is used to characterize the intensity and phase of terahertz pulse trains generated from nonlinear and dispersive interactions in optical fibers. We show that existing FROG retrieval algorithms are easily adapted to allow the retrieval of periodic pulse characteristics and, using synthetic pulse trains generated from numerical simulations, we demonstrate how FROG can differentiate between periodic pulse trains with fundamentally different intensity and phase characteristics, yet qualitatively similar autocorrelation functions and spectra. Experimental results are presented for the FROG characterization of a 0.3-THz sinuso…

Dark three-sister rogue waves in normally dispersive optical fibers with random birefringence

2014

11 pags.; 4 figs.; OCIS codes: (190.3100) Instabilities and chaos; (190.4370) Nonlinear optics, fibers; (060.5530) Pulse propagation and temporal solitons.

Rogue Breather Structures in Nonlinear Systems with an Emphasis on Optical Fibers as Testbeds

2017

Kuznetsov-Ma Soliton Dynamics in Nonlinear Fiber Optics

2012

The Kuznetzov-Ma (KM) soliton is a solution of the nonlinear Schrodinger equation derived in 1977 but never observed experimentally. Here we report experiments showing KM soliton dynamics in nonlinear breather evolution in optical fiber.

Spectral incoherent solitons: a localized soliton behavior in the frequency domain

2008

We show both theoretically and experimentally in an optical fiber system that a noninstantaneous nonlinear environment supports the existence of spectral incoherent solitons. Contrary to conventional solitons, spectral incoherent solitons do not exhibit a confinement in the spatiotemporal domain, but exclusively in the frequency domain. The theory reveals that the causality condition inherent to the nonlinear response function is the key property underlying the existence of spectral incoherent solitons. These solitons constitute nonequilibrium stable states of the incoherent field and are shown to be robust with respect to binary collisions.

An exact soliton solution for an averaged dispersion-managed fibre system equation

2001

We consider the nonlinear wave propagation in an averaged dispersion-managed (DM) fibre system. We present the explicit Lax pair with a variable spectral parameter and derive the exact soliton solution using the Backlund transformation. A similar study is also carried out for simultaneous propagation of N nonlinear pulses in the averaged DM fibre system.

Nonlinear dynamics induced by optical shocks formation

2006

This paper reports on recent studies suggesting that optical shocks can rule the dynamics of cw (or quasi-cw) optical field propagating in glass when common phenomena such as four-wave mixing in fibers or catastrophic self-focusing in bulk are considered. The post-shock oscillations evolve into colliding dark solitons that determine the output pattern in a non-recurrent fashion. This scenario based on the defocusing nonlinear Schrodinger equation and its reduction to a hydrodynamical model is substantially confirmed by our experimental data consisting of recorded output spectra and temporal patterns retrieved from SHG-FROG traces. Numerical results also indicate that, during self-focusing, …

Cross-phase modulational instability induced by Raman scattering in highly birefringent fiber

2013

We report experimental and theoretical studies of Raman-induced cross-phase modulational instabilities (XPMI) in a high-birefringence, normally dispersive optical fiber. Experimental results reveal that the Raman-Stokes wave, generated by a quasi-CW pump beam, interacts with the latter to create a novel type of XPMI sidebands. These sidebands are characterized by a narrow gain bandwidth. The sideband frequencies are well reproduced by a linear stability analysis as well as by full numerical solutions of the coupled generalized nonlinear Schrödinger equations.