ABSTRACT
Electro-optical modulators are key components that enable electrical control of light. This can refer to both phase modulation and intensity modulation. Phase modulation is obtained directly through refractive index modulation. Historically, the variation of the refractive index under application of an electric field is known as the Pockels linear electro-optic effect. It finds its origin in the displacement of the bond charges and in a possible slight deformation of the ion lattice (Yariv and Yeh 1984). The Pockels effect displays negligible dispersion which eases device design and operation specifications. The counterpart of this negligible dispersion is that this effect is weak. This is the reason why guidedwave devices have to be used in order to increase the interaction length between light and the electro-optic material. Phase modulators as well as directional couplers have thus been realized in GaAs-and InP-based materials (Carenco 1987). Intensity modulation has also been made possible using the Pockels effect through the use of Mach-Zehnder interferometers.
