STRONG OPTICAL NONLINEARITIES OF SEMICONDUCTOR QUANTUM WIRES AND DOTS

Picosecond laser saturation spectroscopy method has been applied to in vestigate nonlinear optical properties of semiconductor quantum wires and dots. Discrete bleaching bands have been observed in the time-reso lved nonlinear transmission spectra of GaAs and CdSe quantum wires cry stallized in crysotile asbestos nanotubes with an average diameter of 6 nm, in CdSe nanocrystals (quantum dots) in the glass matrix, in poro us silicon, and in nanocrystals of CdS (CdS has been crystallized in a transparent molecular filter-mica with through empty channels of desi gned diameter). The induced increase of transmission at discrete frequ encies has been attributed to the saturation of optical transitions be tween the energy levels of electrons and holes spatially confined with in quasi-zero-dimensional and quasi-one-dimensional nanostructures and by the phase-space filling of excitons.