Femtosecond and CW optical nonlinearities associated with the spatial separation of electrons and holes in GaAs-AlAs type-II quantum wells are reported. Without applied electric field, the nonlinearities due to blue shift and bleaching of the heavy-hole exciton resonance are observed. An applied static longitudinal electric field changes these nonlinearities through the redistribution of electrons. Furthermore, optical nonlinearities and even gain for ultrahigh excitation conditions in type-II structures are reported and compared to those in similar type-I structures. the theoretical framework used for modeling the type-II system in the presence and absence of electrons is described.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Electrical and Electronic Engineering