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Author: Babushkin, Ihar × Author: Bergé, Luc × Author: Herrmann, Joachim × Author: Skupin, Stefan × End date: 2019 × Start date: 2010 × Type: Text × WGL Institute: WIAS ×

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Now showing 1 - 3 of 3
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    3D numerical simulations of THz generation by two-color laser filaments
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2012) Bergé, Luc; Skupin, Stefan; Köhler, Christian; Babushkin, Ihar; Herrmann, Joachim
    Terahertz (THz) radiation produced by the filamentation of two-color pulses over long distances in argon is numerically investigated using a comprehensive model in full spacetime resolved geometry. We show that the dominant physical mechanism for THz generation in the filamentation regime at clamping intensity is based on quasi-dc plasma currents. The calculated THz spectra for different pump pulse energies and pulse durations are in agreement with previously reported experimental observations. For the same pulse parameters, near-infrared pump pulses at 2 m are shown to generate a more than one order of magnitude larger THz yield than pumps centered at 800 nm.
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    Directionality of THz emission from photoinduced gas plasmas
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2011) Köhler, Christian; Cabrera-Granado, Eduardo; Babushkin, Ihar; Bergé, Luc; Herrmann, Joachim; Skupin, Stefan
    Forward and backward THz emission by ionizing two-color laser pulses in gas is investigated by means of a simple semi-analytical model based on Jefimenko's equation and rigorous Maxwell simulations in one and two dimensions. We find the emission in backward direction having a much smaller spectral bandwidth than in forward direction and explain this by interference effects. Forward THz radiation is generated predominantly at the ionization front and is thus almost not affected by the opacity of the plasma, in excellent agreement with results obtained from a unidirectional pulse propagation model.
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    Ultrafast spatio-temporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2010) Babushkin, Ihar; Kuehn, Wihelm; Köhler, Christian; Skupin, Stefan; Bergé, Luc; Reimann, Klaus; Woerner, Michael; Herrmann, Joachim; Elsaesser, Thomas
    We present a combined theoretical and experimental study of spatio-temporal propagation effects in terahertz (THz) generation in gases using two-color ionizing laser pulses. The observed strong broadening of the THz spectra with increasing gas pressure reveals the prominent role of spatio-temporal reshaping and of a plasma-induced blue-shift of the pump pulses in the generation process. Results obtained from (3+1)-dimensional simulations are in good agreement with experimental findings and clarify the mechanisms responsible for THz emission.