Filters

2011 - 20184

More filters

2019 - 201932020 - 20221
Reset filters

Settings

Author: Tronciu, Vasile × Type: Text ×

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Improvement of output beam quality in broad area lasers with off-axis feedback
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2011) Lichtner, Mark; Tronciu, Vasile; Vladimirov, Andrej G.
    We report a method to improve the beam quality of broad area lasers by using a V-shaped external cavity formed by two off-axis feedback mirrors that allow to select a single transverse mode with the intensity modulated in the transverse direction. We find that in the case when one of the two feedback mirrors is absent a spontaneous formation of self-induced transverse population grating leading to a reduction of the lasing threshold is observed. Most favorable conditions for stabilization of single transverse supermode and creation of a high power and high brightness plane wave traveling in the extended cavity are obtained for equal re ectivities of the two external reflectors.
  • Thumbnail Image
    Item
    Tunable semiconductor ring laser with filtered optical feedback: Traveling wave description and experimental validation
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2017) Radziunas, Mindaugas; Khoder, Mulham; Tronciu, Vasile; Danckaert, Jan; Verschaffelt, Guy
    We study experimentally and theoretically a semiconductor ring laser with four filtering channels providing filtered delayed optical feedback. To describe and analyze the wavelength selection and tuning in this device, we exploit the traveling-wave model determining the evolution of optical fields and carrier density along the ring cavity and filtering branches. The numerical results agree with the experimental observations: we can reproduce the wavelength tuning, the multiple wavelength emission, and the wavelength switching speed measured in these devices. The traveling-wave model allows us to study in detail the effect of the different laser parameters and can be useful for designing the future devices.
  • Thumbnail Image
    Item
    Amplifications of picosecond laser pulses in tapered semiconductor amplifiers : numerical simulations versus experiments
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2011) Tronciu, Vasile; Schwertfeger, Sven; Radziunas, Mindaugas; Klehr, Andreas; Bandelow, Uwe; Wenzel, Hans
    We apply a travelling wave model to the simulation of the amplification of laser pulses generated by Q-switched or mode-locked distributed-Bragg reflector lasers. The power amplifier monolithically integrates a ridge-waveguide section acting as pre-amplifier and a flared gain-region amplifier. The diffraction limited and spectral-narrow band pulses injected in to the pre-amplifier have durations between 10 ps and 100 ps and a peak power of typical 1 W. After the amplifier, the pulses reach a peak power of several tens of Watts preserving the spatial, spectral and temporal properties of the input pulse. We report results obtained by a numerical solution of the travelling-wave equations and compare them with experimental investigations. The peak powers obtained experimentally are in good agreement with the theoretical predictions. The performance of the power amplifier is evaluated by considering the dependence of the pulse energy as a function of different device and material parameters.