Recent developments in multiple quantum well acousto-optic and electro-optic modulator structures

Optical modulators based on acoustooptic and electrooptic effects in multiple quantum well (MQW) and superlattice structures are reviewed. In the case of MQW layers the primary mechanism used is the quantum confined Stark effect (QCSE). Modulators utilizing enhanced changes in optical parameters such as absorption, index of refraction, and birefringence due to externally applied or induced electric fields in AlGaAs-GaAs and InGaAs-GaAs structures are described. In particular, various types of MQW Bragg devices, heterostructure acoustic charge transport modulators, and birefringent light valves are discussed from theoretical and experimental viewpoints. In addition, modulators based on acoustooptic effects in superlattices are reviewed. The application of modulators in the realization of subsystems such as of two-dimensional spatial light modulators (SLMs) and optical correlators is also presented