Coherent control of quantum-well excitons in a resonant semiconductor microcavity for high-speed all-optical switching

Coherent control of excitons in quantum wells embedded in a resonant planar semiconductor microcavity versus in quantum wells without the cavity at high repetition rates is investigated theoretically to determine the practical constraints for application in high bit-rate optical switching. It is shown that π-shifted pulse pairs are optimal to coherently populate and depopulate the QW on the 100-fs timescale. For the cavity-free case, the small optical nonlinearity will require devices incorporating ~100 quantum wells; the resonant enhancement of the confined mode for the case of the cavity leads to an effective increase in the optical nonlinearity and thus a reduction of the required number of quantum wells to ~10. In addition, switch architectures that avoid interferometers, and thus will have superior temperature and mechanical stability, based on the microcavity are proposed. We believe that although room-temperature operation of a 100-Gb/s switch based on this principle may be difficult, operation at liquid-nitrogen temperature should be feasible