Electromagnetically-induced transparency and slow light in GaAs/AlGaAs multiple quantum wells in a transient regime.

Electromagnetically-induced transparency (EIT) is observed and analyzed for the group velocity of a femtosecond light pulse interacting with GaAs/AlGaAs multiple quantum wells (MQWs) in a transient regime. The calculated slowdown factor of the group velocity inside the medium due to the dynamic refractive index change is approximately 2.10 x 10(3).

Optical nonlinearities of Au nanoparticles and Au/Ag coreshells.

Au nanoparticles exhibited both negative and positive nonlinear absorptions with ground-state plasmon bleaching and free-carrier absorption that could be origins of the saturable and reverse-saturable optical properties. Au/Ag coreshells displayed only positive nonlinear absorption and reverse-saturable optical properties as a function of excitation intensity at the edge of surface-plasmon resonance, which implies no ground-state plasmon bleaching and the existence of two-photon absorption.