Stochastic Analysis and Nonlinear Dynamics Seminar Series
Prof. George Tsironis
Professor, Department of Physics, University of Crete & Visiting Fellow, SEAS, Harvard University
Wave propagation in complex media: extreme events, branching and chimeras
Wave propagation in complex media involves extreme phenomena such as branching and rogue-type waves. We focus on both discrete and continuous systems; in the discrete case the systems are nonlinear  while in the continuous one are made of gradient index lenses that provide strong scattering . We investigate the statistics of extreme events and find the features that lead to rogue wave formation. In the continuous case of a disordered linear medium we find that while nonlinearity does not seem to be very important, strong scattering is a necessary condition for extreme events . We also investigate the onset of branching in electronic flows and show that in the ultra-relativistic case, applied to doped graphene, a specific relation for the first passage to the branching regime as a function of surface disorder exists that may be discernible experimentally. Finally we discuss the onset of partial coherence in complex media and show that turbulent chimeras may result in the discrete limit .
 Extreme events in discrete nonlinear disordered lattices, A. Maluckov, Lj. Hadzievski, N. Lazarides, G.P. Tsironis, Phys. Rev. E 79, 025601 (2009).
 M. Mattheakis, G. P. Tsironis, Extreme waves and branching flows in optical media, In: J.F.R. Archilla, N. Jimènez, V.J. Sànchez-Morcillo, L.M. Garcı̀a-Raffi (eds.). Quodons in mica: Nonlinear localized travelling excitations in crystals, Springer series in materials science pp 425-454 (2015).
 M. Mattheakis, I. J. Pitsios, G. P. Tsironis and S. Tzortzakis, Extreme events in complex linear and nonlinear photonics media, Chaos, Solitons and Fractals, 84, 73 (2016).
 J. Shena, J. Hizanidis, V. Kovanis, and G. P. Tsironis: Turbulent chimeras in large semiconductor laser arrays, Scientific Reports 7, 42116 (2017).