FIELD-INDUCED 4-WAVE-MIXING SIGNAL IN SEMICONDUCTOR SUPERLATTICES

The four-wave mixing (FWM) signal of a semiconductor superlattice with an external electric field is evaluated using the semiconductor Bloch equations. It is found that the FWM signal for a GaAs/AlGaAs-semicond uctor superlattices with a lattice constant d has a deep valley when t he electric field is around eFd = 1 meV. It is also found that the dee p valley comes mainly from the broken inversion symmetry caused by the exteral electric field and that the field intensity determines the si gn and the magnitude of the Coulomb-induced optical nonlinearities.