Abstract

Coherent optical properties of semiconductors have been a field of great interest within the last ten years/ but optoelectronic devices are still entirely based on manipulation of charge density. Only recently has optical phase control in semiconductors been demonstrated, which may add a new dimension to device operation. These experiments showed that the relative phase of two light pulses allows control of carrier dynamics when their separation is less than the coherence time of the excited system.^2,3 Here we apply coherent control to manipulate density and spin dynamics of excitons in quantum wells. We contrive complete destruction of photoexcited exciton populations within a few hundred femtoseconds of their creation to induce ultrafast excitonic nonlinearities. This technique combines the strength of resonant with the speed of nonresonant transitions and is, therefore, promising for ultrafast optical devices, which would not suffer from long-lived persistent carrier populations. Coherent spin control allows the switching between different spin populations.

© 1996 Optical Society of America