Optical modulators are key components in the design of high speed optical communication systems. In particular, Electro Optic Mach-Zehnder modulators (EO MZM) realized in LiNbO3 ere a well established and reliable solution in long haul communication suitable to encode both analog and digital information. Even though the operating principle is the linear electro-optic effect (Pockels Effect), these devices are considered interferometers since they exploit the interference between two phase shifted light beams to obtain an amplitude modulation. The appealing feature of LiNbO_3 MZM is the possibility to obtain a good trade off between the need to have low loss, low driving voltages broad bandwidth and low chirp, while a big drawback is the large footprint (cm ^2) that poses a severe limitation when compact and performing devices are need \cite{Haffner1}.