Modelling an electro-optical modulator based on a vertical p – n junction in a silicon-on-insulator structure

We report the results of numerical simulation of a Mach–Zehnder electro-optical modulator using beam splitters based on multimode interference in a silicon-on-insulator structure. The control is provided due to the depletion effect in the vertical p – n junction, which can be fabricated using the self-alignment technology. An optimal modulator design is proposed, which impedance is matched with an external 50-Ω load, for which, with a reverse bias of –5 V and an active length of 1.7 mm, the optical frequency bandwidth of ~50 GHz can be achieved. A special doping profile of the p – n junction of the modulator is presented, which provides an optical frequency bandwidth of 30 GHz with a reverse bias of –3 V and a modulator length of 2.5 mm. Such modulators can be used in integrated optics, optical communications and radio photonics devices.