Tool Used: LaserMOD
Silicon is the desired material system for integrated electo-optical devices due to its mature fabrication technology. However, not all the desired optical functionality has yet been achieved. One recent advance has been in the area of high-speed optical modulation in SOI (silicon on insulator) waveguides . These devices rely on carrier dependent absorption/index effects  to modulate the propagating light. Until now, such devices have generally been slow, but an innovation that yields improved frequency response is the use of a MOS configuration. This creates a carrier accumulation channel near a thin buried oxide layer that can be controlled much faster than charge injected everywhere in the waveguide.
The model for charge-dependent absorption/index changes is given by Soref , and a self-consistent solution of Poisson's equation and the carrier continuity equations is used to determine the carrier densities everywhere in the device as a function of applied voltage. These models are all contained in the active device simulator, LaserMOD™.