Field-Induced Four-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-semiconductor superlattices with a lattice constant d has a deep valley when the electric field is around eF d = 1 meV. It is also found that the deep valley comes mainly from the broken inversion symmetry caused by the exteral electric field and that the field intensity determines the sign and the magnitude of the Coulomb-induced optical nonlinearities.