Abstract
A numerical model of bulk electroabsorption modulators has been developed. It consists of a quasi-2D representation based on a drift-diffusion approach and includes the presence of heterostructures and Fermi statistics for the carriers. The non-linear behavior of this type of device, essentially related to the pile-up and the space-charge effects, has been analyzed. Simulations results have been compared with laboratory measurements on a fabricated device that presents an abrupt heterojunction, obtaining a good agreement. Two other types of structures have been simulated, one obtained with the inclusion of a thin quaternary layer and the other with a graded heterojunction, which eliminate the hole pile-up at the InGaAsP-InP heterointerface. The paper demonstrates that it is possible to approach the optimum behavior of the modulator using both the alternatives considered here. Finally, non linear effects in short modulators has been investigated.