Quantum-Confined Stark-Effect Optical Modulator in Ge/SiGe Quantum-Well Structures
Optical modulators for silicon photonics - a real revolution in optical communication systems of tomorrow

Building a silicon optical modulator using carrier depletion and featuring high optical bandwidth (i.e. excluding resonant structures) requires the use of an active region several mm long, creating significant power consumption. The realization of a compact modulator will only be possible by proposing innovative concepts that break with current technologies. With this in mind, we have been researching the optical properties of direct bandgaps in Ge/SiGe quantum well structures since 2009. The aim is to study the variation of the absorption coefficient to create optical modulators.

The effect exploited is the Quantum Confined Stark Effect (QCSE), first illustrated by Stanford University in Ge/SiGe multi-well structures with high germanium concentration....