All-optical switching between optical bistability and multistability in a defect dielectric medium doped with a...

In this paper, optical bistability (OB) and multistability (OM) properties of a defect dielectric slab are studied. A GsAs multiple quantum well nanostructure (MQW) with 17.5 nm GaAs wells and 15 nm Al(0.3) Ga(0.7) barriers is used in the dielectric medium as a defect layer. Therefore, properties of the refractive index of the slab can be changed in the presence of MQWs. It is observed that switching from OB to OM can be obtained by controlling some external parameters. We find that the exciton spin relaxation and thickness of the slab have essential roles in adjusting the OB and OM properties of the probe light through the slab. Moreover, transmission, reflection, and absorption properties of the propagating pulse through the slab are also discussed. We show that the subluminal and superluminal light transmission or reflection can be obtained via amplification of the probe pulse through the medium. We hope that our proposed model may be suitable for the development of nanoscale devices in all-optical quantum information technology.