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End date: 2019 × Start date: 2010 × DDC: 530 × Type: Text × Subject: Differential equations × WGL Institute: WIAS ×

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Now showing 1 - 4 of 4
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    Delay-induced dynamics and jitter reduction of passively mode-locked semiconductor lasers subject to optical feedback
    (Bristol : IOP, 2012) Otto, C.; Lüdge, K.; Vladimirov, A.G.; Wolfrum, M.; Schöll, E.
    We study a passively mode-locked semiconductor ring laser subject to optical feedback from an external mirror. Using a delay differential equation model for the mode-locked laser, we are able to systematically investigate the resonance effects of the inter-spike interval time of the laser and the roundtrip time of the light in the external cavity (delay time) for intermediate and long delay times. We observe synchronization plateaus following the ordering of the well-known Farey sequence. Our results show that in agreement with the experimental results a reduction of the timing jitter is possible if the delay time is chosen close to an integer multiple of the inter-spike interval time of the laser without external feedback. Outside the main resonant regimes the timing jitter is drastically increased by the feedback.
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    Robust homoclinic orbits in planar systems with Preisach hysteresis operator
    (Bristol : IOP Publ., 2016) Pimenov, Alexander; Rachinskii, Dmitrii
    We construct examples of robust homoclinic orbits for systems of ordinary differential equations coupled with the Preisach hysteresis operator. Existence of such orbits is demonstrated for the first time. We discuss a generic mechanism that creates robust homoclinic orbits and a method for finding them. An example of a homoclinic orbit in a population dynamics model with hysteretic response of the prey to variations of the predator is studied numerically.
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    Far field imaging of a dielectric inclusion
    (Bristol : IOP Publ., 2015) Wahab, Abdul; Ahmed, Naveed; Abbas, Tasawar
    A non-iterative topological sensitivity framework for guaranteed far field detection of a dielectric inclusion is presented. The cases of single and multiple measurements of the electric far field scattering amplitude at a fixed frequency are taken into account. The performance of the algorithm is analyzed theoretically in terms of resolution, stability, and signal-to-noise ratio.
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    Convective Nozaki-Bekki holes in a long cavity OCT laser
    (Washington, DC : Soc., 2019) Slepneva, Svetlana; O'Shaughnessy, Ben; Vladimirov, Andrei G.; Rica, Sergio; Viktorov, Evgeny A.; Huyet, Guillaume
    We show, both experimentally and theoretically, that the loss of coherence of a long cavity optical coherence tomography (OCT) laser can be described as a transition from laminar to turbulent flows. We demonstrate that in this strongly dissipative system, the transition happens either via an absolute or a convective instability depending on the laser parameters. In the latter case, the transition occurs via formation of localised structures in the laminar regime, which trigger the formation of growing and drifting puffs of turbulence. Experimentally, we demonstrate that these turbulent bursts are seeded by appearance of Nozaki-Bekki holes, characterised by the zero field amplitude and π phase jumps. Our experimental results are supported with numerical simulations based on the delay differential equations model.