Recent developments and applications in electroabsorption semiconductor modulators

State of the art developments in electroabsorption modulators that utilize quantum well-semiconductors are reviewed. Special emphasis is given to recent progress made in materials for modulators. On technological grounds, optimized Multiple Quantum Well modulators in the GaAs/AlGaAs system have been driven by applications in photonic switching and optical interconnects. Surprisingly, these same structures exhibit a wealth of new behavior that ranges from Bloch oscillations to excitons in Coupled Well, Wannier–Stark and Shallow Well superlattices. Several types of excitonic phases have been identified, optically and found to transform as the system dimensionality changes from 2D to 3D. In addition, new material systems have shown that quantum well excitonic absorption quality can be transferred to technologically important wavelengths at 1.06 or 1.55 μm.