Nonlinear optical properties and ultrafast response of GaAs-AlAs type-II quantum wells

Type-2 multiple quantum-wells (MQWs) are analyzed in terms of their optical nonmlinearities. Indirect transition energies are diverted by the space-charge potential resulting from the separation of electrons from holes in the MQWs while direct transitions remain unaffected by the space-charge field. A Coulomb-enhancement peak occurs at the hole quasi-chemical with the blue shift developing fully as low lattice temperatures are reached in hole distribution.