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Author: Radziunas, Mindaugas × End date: 2018 × DDC: 530 × Type: Text × Version: publishedVersion × WGL Institute: WIAS ×

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    Study of wavelength switching time in tunable semiconductor micro-ring lasers: experiment and travelling wave description
    (Washington, DC : OSA, 2018) Khoder, Mulham; Radziunas, Mindaugas; Tronciu, Vasile; Verschaffelt, Guy
    We report in this paper the wavelength switching features of semiconductor ring lasers that are wavelength tunable based on filtered optical feedback. The filtered feedback provides a wavelength dependent loss mechanism in these devices with which a particular longitudinal mode, and thus a particular wavelength, can be selected by changing the filter characteristics of the feedback channel. We investigate how the wavelength switching speed depends on the amplitude of the modulation of the switching driving signal and on the different phase factors within the filtering branches of the SRL. We compare qualitatively the experimental results with numerical simulations based on a travelling wave model. We also investigate the dynamical behavior of the lasing and nonlasing longitudinal modes in the two channels of the clockwise and the counter-clockwise directions. We show the crucial importance of various phase relation factors on the wavelength switching behavior. Finally, we discuss what limits the switching speed and how we can accelerate it.
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    Compact high order finite difference schemes for linear Schrödinger problems on non-uniform meshes
    (Berlin: Weierstraß-Institut für Angewandte Analysis und Stochastik, 2012) Radziunas, Mindaugas; Čiegis, Raimondas; Mirinavičius, Aleksas
    In the present paper a general technique is developed for construction of compact high-order finite difference schemes to approximate Schrödinger problems on nonuniform meshes. Conservation of the finite difference schemes is investigated. Discrete transparent boundary conditions are constructed for the given high-order finite difference scheme. The same technique is applied to construct compact high-order approximations of the Robin and Szeftel type boundary conditions. Results of computational experiments are presented