Search results for "Modula"
showing 10 items of 1481 documents
Experimental evidence of the real multimode nature of geometric parametric instability
2020
We show experimentally that geometric parametric instability in graded-index multimode fibers is composed by several multimode spectral components. The experimental observation is obtained by using a new 3D technique of high-resolution spatial and spectral analysis.
Higher-order modulation instability in optical fibers
2012
International audience; We report on theoretical, numerical and experimental study of a new form of instability in a nonlinear fiber. This process of higher-order modulation instability arises from the nonlinear superposition of elementary instability dynamics.
Universal spectral dynamics of modulation instability : theory, simulation, experiment
2011
A central process of nonlinear fibre optics is modulation instability (MI), where weak perturbations on a continuous wave are amplified to generate a parametric cascade of spectral sidebands. Although studied for many years, it has only been recently appreciated that MI dynamics can be described analytically by Akhmediev breather (AB) solutions to the nonlinear Schrodinger equation (NLSE) [1]. This has led to important results, including the first observation of the Peregrine Soliton [2]. AB theory has also shown that the spectral amplitudes at the peak of the MI gain curve yield a characteristic log-triangular spectrum, providing new insight into the initial phase of supercontinuum generat…
Experimental observation of the spectral Gouy phase shift
2013
We experimentally observe and measure the spectral phase shift of a pulse subjected to spectral focusing. We find a phase shift of π/2, reaffirming the Gouy phase shift as a general consequence of wave confinement whether in space/momentum or frequency/time coordinates.
All-Fibered High-Quality 20-GHz and 40-GHz Picosecond Pulse Generator
2011
International audience; In this work, we investigate the generation of 20 and 40 GHz pulse trains by nonlinear compression of an initial beating in a cavity-less optical-fiber-based configuration. High temporal stability is obtained by generating the sinusoidal beating by means of an intensity modulator driven by an external clock. The residual timing jitter induced by the RF phase modulation is then reduced by managing the cumulated dispersion of the compression line whereas complete polarization stabilization is obtained thanks to a modified setup including a Faraday rotator mirror. Finally a high-quality 160 Gbit/s signal is generated from our low duty-cycle 40 GHz pulse source thanks to…
Dissipative Optical Breather Molecular Complexes
2020
We demonstrate different types of breathing soliton complexes in a mode-locked fibre laser: multi-breather molecules, and molecular complexes arising from the binding of two breather-pair molecules or a breather-pair molecule and a single breather.
Real-time measurements of spontaneous breathers and rogue wave events in optical fibre modulation instability
2016
Modulation instability is a fundamental process of nonlinear science, leading to the unstable breakup of a constant amplitude solution of a physical system. There has been particular interest in studying modulation instability in the cubic nonlinear Schrödinger equation, a generic model for a host of nonlinear systems including superfluids, fibre optics, plasmas and Bose–Einstein condensates. Modulation instability is also a significant area of study in the context of understanding the emergence of high amplitude events that satisfy rogue wave statistical criteria. Here, exploiting advances in ultrafast optical metrology, we perform real-time measurements in an optical fibre system of the u…
Two-stage linear-nonlinear shaping of an optical frequency comb as rogue nonlinear-Schrödinger-equation-solution generator
2014
International audience; We report a wave generator of complex solutions of the nonlinear Schrödinger equation (NLSE) combining both intensity and phase spectral shaping of an initial optical frequency comb with subsequent nonlinear propagation in an optical fiber. We apply the explicit analytical form of the two-breather solutions of the NLSE as a linear spectral filter to shape ideal modulation of a continuous wave. The additional nonlinear propagation of the tailored wave provides experimental evidence of both the growth and decay of the fundamental second-order periodic breather solution. The temporal and spectral profiles of the higher-order breather are in excellent agreement with the …
Temporal dynamics of incoherent waves in noninstantaneous response nonlinear Kerr media
2012
International audience; We consider the temporal evolution of an incoherent optical wave that propagates in a noninstantaneous response nonlinear medium, such as single mode optical fibers. In contrast with the expected Raman-like spectral redshift due to a delayed nonlinear response, we show that a highly noninstantaneous response leads to a genuine modulational instability of the incoherent optical wave. We derive a Vlasov-like kinetic equation that provides a detailed description of this process of incoherent modulational instability in the temporal domain.
Seeded and spontaneous higher-order modulation instability
2012
International audience; We report on the dynamics of the higher-order modulation instability in optical fibers and show that it is the very same phenomenon that underpins the emergence of rogue waves in the early stage of supercontinuum generation.