Resonant solitons in semiconductors: Transparency induced by exciton-exciton interactions

William Huhn

Harald W. Giessen, J. Kühl, Andreas Knorr +1 more

Irina B. Talanina

The form invariant coherent pulse propagation in semiconductors excited at 1s-exciton resonance is studied analytically using the reduced semiconductor Maxwell-Bloch equations. The sech-shaped pulse solution for excitonic self-induced transparency (SIT) is presented, showing significant difference in comparison with the well known SIT solution for non-interacting two-level systems. In contrast to 2π pulses in atomic systems, the phenomenon of SIT of interacting excitons in semiconductors occurs for the pulses of area 1.07π. Possible applications of the SIT solitons in semiconductor all-optical switching devices are discussed.

Ángela M. Guzmán, M. Romagnoli, Stefan W. Wabnitz

We investigate self-induced transparency soliton switching in a nonlinear two-level resonant dual-waveguide directional coupler. The soliton transfer properties of the coupler depend on the input pulse area; for areas larger than π, an integer number of 2π solitons is transmitted from the output ports. Tapered coupling provides digital transmission characteristics. A specific example of application to impurity bound excitons in semiconductors is discussed.

Hermann Haken, J. Goll, Axel Schenzle

Harald W. Giessen, Stefan Lindén, J. Kühl +2 more

Summary form only given.Free-exciton resonances in semiconductors cannot be treated as bare two-level systems because Coulomb interaction and correlation/exchange effects between the carriers substantially modify the optical Bloch equations that describe the behavior of a two-level system under the influence of an external light field. The semiconductor Bloch equations (SBEs) give a more realistic description of the dynamic response of the system on ultrafast time scales. Therefore, the coherent transients known from two-level systems in atomic physics have been found to be substantially modified in semiconductors. Whereas self-induced transparency (SIT) on bound excitons, which are known to behave as atomiclike two-level systems, has been found, the question whether SIT could also appear on a free-exciton resonance is still subject of controversial discussions. We addressed this problem in a combined theory-experiment study.