Browsing by Subject "Graded-index multimode fibers"

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    Geometric parametric instability of femtosecond pulses in graded-index multimode fiber
    (Optical Society of America, 2017) Teğin, Ugur; Ortaç, Bülend
    We numerically and experimentally study the spatio-temporal femtosecond pulse evolution in graded-index multimode fiber at normal dispersion regime. We report the first demonstration of geometric parametric instability sidebands generation with ultrashort pulses in the literature.
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    ItemOpen Access
    Spatiotemporal instability of femtosecond pulses in graded-index multimode fibers
    (Institute of Electrical and Electronics Engineers Inc., 2017) Teǧin, U.; Ortaç, B.
    We study the spatiotemporal instability generated by a universal unstable attractor in normal dispersion graded-index multimode fiber for femtosecond pulses for the first time. Experimentally observed spatiotemporal instability sidebands are 91-THz detuned from the pump wavelength of 800 nm. Detailed analysis carried out numerically by employing coupled-mode pulse propagation model. Numerically obtained results are well-aligned with experimental observations. Spatial evolution of the total field and spatiotemporal instability sidebands is calculated numerically, and for the input pulses of 200-fs duration, formation and evolution of spatiotemporal instability are shown in both spatial and temporal domains. Our results present the unique features of spatiotemporal instability, such as remarkable frequency shift with inherited beam shape of instability sidebands.