28 research outputs found
Brillouin scattering-induced rogue waves in self-pulsing fiber lasers
We report the experimental observation of extreme instabilities in a self-pulsing fiber laser under the influence of stimulated Brillouin scattering (SBS). Specifically, we observe temporally localized structures with high intensities that can be referred to as rogue events through their statistical behaviour with highly-skewed intensity distributions. The emergence of these SBS-induced rogue waves is attributed to the interplay between laser operation and resonant Stokes orders. As this behaviour is not accounted for by existing models, we also present numerical simulations showing that such instabilities can be observed in chaotic laser operation. This study opens up new possibilities towards harnessing extreme events in highly-dissipative systems through adapted laser cavity configurations
'Universal' FitzGerald Contractions
The model of a universe with a preferred frame, which nevertheless shares the
main properties with traditional special and general relativity theories, is
considered. We adopt Mach's interpretation of inertia and show that the energy
balance equation, which includes the Machian energy of gravitational
interactions with the universe, can imitate standard relativistic formulas.Comment: The version accepted by Eur. Phys. J.
The dynamics of waves interacting with the Equatorial Undercurrent
We propose a new, simple model – but one which has far-reaching consequences – to describe the interaction between waves that propagate across the Pacific Ocean and the Equatorial Undercurrent (EUC). This involves a detailed discussion of the full linear problem as it relates to the dynamic coupling between the surface waves and the internal waves on the thermocline. The result is a comprehensive description of the system close to the Equator, and how the structure of the EUC affects the wave properties; in particular, the analysis holds for arbitrary wavelengths and finite depths. Although the final expressions, for general wavelengths, are too cumbersome for direct interpretation, we are able to produce simple formulae for the speeds of the waves, and the attenuation factor between the two families of waves, for short, intermediate and long waves. Further, our results predict the appearance of critical layers under certain circumstances; by reverting to our original system of governing equations, we are able to derive the relevant nonlinear structure of the flow in these layers. Our results are in good agreement with the available field data.</p