Ultrafast dynamics after optical pulse excitation in semiconductor waveguide structures

  • Hvam, Jørn Marcher (Project Manager)
  • Borri, Paola (Project Participant)
  • Mørk, Jesper (Project Participant)
  • Langbein, Wolfgang Werner (Project Participant)
  • Scaffetti, Stefano (Project Participant)
  • Romstad, Francis (Project Participant)
  • Bimberg, Dieter (Project Participant)
  • Ledentsov, Nikolaj (Project Participant)
  • Martelli, F. (Project Participant)

    Project Details

    Description

    Short optical pulse excitation is a direct tool in order to investigate ultrafast non-linear changes in the gain and refractive index in semiconductor optical amplifiers. We use two different techniques: single pulse propagation and pump-probe.
    In the first case, after injection of a single pulse into the amplifier, we measure the total energy of the pulse at the output of the device, the profile in frequency and real time and the pulse chirp. The technique has been tested on a InGaAsP bulk amplifier operating at 1.53mm. The measurements of the output energy indicate saturation of the gain for intense input pulses, and a non-linear gain compression dominating for pulse duration lower than 10ps. The pulse profile in time and frequency and the pulse chirp reveal strong non linear effects giving rise to a break-up of the pulse for very high (~100pJ) input energy, related to self-phase modulation occurring in the strong saturation regime.
    The second technique is a pump-probe experiment in heterodyne detection scheme to directly measure non-linear gain compression coefficients and ultrafast carrier dynamics in the amplifier. The technique has been tested on the bulk device. Pump-probe measurements have been also performed on InAs quantum dot (QD) amplifiers showing new interesting results on the carrier dynamics of these devices, like an ultrafast carrier capture time (
    StatusFinished
    Effective start/end date01/03/199731/12/1999