Ultrafast gain and index dynamics in a semiconductor optical amplifier: theory and experiment

H.J.S. Dorren, X. Yang, D. Lenstra, H. Waardt, de, G.D. Khoe, T. Simoyama, H. Ishikawa, H. Kawashima, T. Hasama

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We explain how a semiconductor optical amplifier in a Sagnac-interferometric arrangement can be used for switching of 200 fs optical pulses. The switching principles are based on gain and index saturation dynamics on a sub-picosecond timescale. We present a model that accounts for bi-directional propagation of ultrashort optical pulses through the amplifier as well as free-carrier absorption and two-photon absorption. We have also carried out pump and probe experiments to measure the ultrafast refractive index dynamics of a multi-quantum well InGaAsP-InGaAs semiconductor optical amplifier that is operated in the gain regime. The pump and probe pulses are cross-linearly polarized. We observe a phase shift of 200 degrees if the amplifier is pumped with 120 mA of current, but find that the phase shift vanishes if the injection current is increased to 160 mA. Our results indicate a contribution of two-photon absorption to the nonlinear phase shift that opposes the phase shift introduced by the gain. Finally, we observe that the phase shift comes up and disappears within a picosecond.
Original languageEnglish
Title of host publicationPhysics and Simulation of Optoelectronic Devices XI, San Jose, California, USA
EditorsMarek Osinski, Hiroshi Amano, Peter Blood
Place of PublicationBellingham
Publication statusPublished - 2003
EventPhysics and Simulation of Optoelectronic Devices XI - San Jose, United States
Duration: 27 Jan 200331 Jan 2003

Publication series

NameProceedings of SPIE


ConferencePhysics and Simulation of Optoelectronic Devices XI
Country/TerritoryUnited States
CitySan Jose


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