NONLINEAR-OPTICAL ABSORPTION IN SEPARATE-CONFINEMENT MULTI-QUANTUM-WELL STRUCTURES DUE TO SPATIAL BAND BENDING

We report on nonlinear optical. absorption in InGaAs/InGaAsP separate confinement multiple-quantum-well (SCMQW) structures based on charge-c arrier induced band bending. Carrier induced localization and related changes in absorption strength due to spatial separation of electrons and holes are utilized to design SCMQW structures with a new type of o ptical nonlinearity. Experimentally, we observe strong changes in opti cal absorption with increasing excitation power. Compared to exciton b leaching, the new nonlinearity dominates at low carrier densities.