A MECHANISM FOR LOW-POWER ALL-OPTICAL SWITCHING IN MULTIPLE-QUANTUM-WELL STRUCTURES

We demonstrate a novel type of optical switching mechanism in pin sepa rate confinement multiple quantum well (SCMQW) structures. By introduc ing additional large barriers into conventional InGaAs(P)/InP SCMQW st ructures, the transport of photogenerated holes can be controlled in s uch a way that they accumulate in the intrinsic region. This positive space charge leads to a local screening of the internal held in the op tical confinement layer and to an enhancement of the internal field in the MQW region. We characterize the optical nonlinearity, which is ba sed on the quantum confined Stark effect (QCSE), experimentally and th eoretically. As the nonlinearity is observed at input powers < 1 W/cm( 2) in the basic nonoptimized structures presented here, we propose to use our structure especially for low-power optical switches. (C) 1996 American Institute of Physics.