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    Item type:Publication, Access status: without files ,
    Optical push broom in a silicon waveguide
    (2020-03)
    Gaafar, Mahmoud Abdelaziz
    ;
    Li, He
    ;
    Cai, Xinlun
    ;
    Li, Juntao
    ;
    Eich, Manfred
    We report on light trapping by a moving refractive index front inside a silicon waveguide, the so-called optical push broom effect. The front generated by a fast pump pulse collects and traps the energy of a signal wave with smaller group velocity tuned near to the band gap of the waveguide with hyperbolic dispersion. The energy of the signal wave is accumulated inside the front and distributed in frequency. The presented effect can be utilized to compress signals in time and space.
    Publicationtype: Conference Paper
      80
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    Item type:Publication, Access status: without files ,
    Front induced transitions: Refractive index fronts in dispersive waveguides
    (SPIE, 2020-03)
    Gaafar, Mahmoud Abdelaziz
    ;
    Renner, Hagen
    ;
    Baba, Toshihiko
    ;
    Eich, Manfred
    ;
    Petrov, Alexander
    Moving refractive index fronts in waveguides with dispersion is a special type of spatio-temporal modulation leading to the change of signal frequency and wavenumber. The interaction of light with such fronts allows frequency conversion, light stopping, optical delays as well as bandwidth and pulse duration manipulation. We will present theoretical and experimental examples of signal transmission, reflection and trapping by the front and highlight special situations such as light stopping, time reversal or optical push broom effect. We will geometrically consider indirect transitions in the dispersion relation using the phase continuity relation at the front and present numerical solutions of the linear Schrödinger equation which follows from the slowly varying envelope approximation of the wave equation. In particular, for highly dispersive waveguides a temporal evolution of the spatial wave envelopes are considered in contrast to conventional spatial evolution of temporal envelopes. Further, we will present an overview of experimental results and estimate the maximal achievable effects for each of the application in different waveguide systems.
    Publicationtype: Conference Paper
      66