Coherent all-optical polarization switching in quantum wells

A coherent all-optical nonlinear polarization switch based on exciton-exciton correlations is demonstrated in a multiple-quantum-well semiconductor structure. A contrast ratio of 8:1 and a relaxation time of less than a picosecond are reported at 80 K using only 10 wells. The results are compared to a similar switch, which makes use of electron spin.