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Subject: synchronization × WGL Institute: WIAS ×

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    Noise-induced dynamical regimes in a system of globally coupled excitable units
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2021) Klinshov, Vladimir V.; Kirillov, Sergey Yu.; Nekorkin, Vladimir I.; Wolfrum, Matthias
    We study the interplay of global attractive coupling and individual noise in a system of identical active rotators in the excitable regime. Performing a numerical bifurcation analysis of the nonlocal nonlinear Fokker-Planck equation for the thermodynamic limit, we identify a complex bifurcation scenario with regions of different dynamical regimes, including collective oscillations and coexistence of states with different levels of activity. In systems of finite size this leads to additional dynamical features, such as collective excitability of different types, noise-induced switching and bursting. Moreover, we show how characteristic quantities such as macroscopic and microscopic variability of inter spike intervals can depend in a non-monotonous way on the noise level.
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    Chimera states in pulse coupled neural networks: The influence of dilution and noise
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2016) Olmi, Simona; Torcini, Alessandro
    We analyse the possible dynamical states emerging for two symmetrically pulse coupled populations of leaky integrate-and-fire neurons. In particular, we observe broken symmetry states in this set-up: namely, breathing chimeras, where one population is fully synchronized and the other is in a state of partial synchronization (PS) as well as generalized chimera states, where both populations are in PS, but with different levels of synchronization. Symmetric macroscopic states are also present, ranging from quasi-periodic motions, to collective chaos, from splay states to population anti-phase partial synchronization. We then investigate the influence disorder, random link removal or noise, on the dynamics of collective solutions in this model. As a result, we observe that broken symmetry chimeralike states, with both populations partially synchronized, persist up to 80% of broken links and up to noise ︠amplitudes
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    Stripe-array diode-laser in an off-axis external cavity : theory and experiment
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2009) Jechow, Andreas; Lichtner, Mark; Menzel, Ralf; Radziunas, Mindaugas; Skoczowsky, Danilo; Vladimirov, Andrei
    Stripe-array diode lasers naturally operate in an anti-phase supermode. This produces a sharp double lobe far field at angles α depending on the period of the array. In this paper a 40 emitter gain guided stripe-array laterally coupled by off-axis filtered feedback is investigated experimentally and numerically. We predict theoretically and confirm experimentally that at doubled feedback angle 2α a stable higher order supermode exists with twice the number of emitters per array period. The theoretical model is based on time domain traveling wave equations for optical fields coupled to the carrier density equation taking into account diffusion of carriers. Feedback from the external reflector is modeled using Fresnel integration.