SOI photonic circuits for optical communication systems

Circuits and Systems for Receiving, Transmitting and Signal Processing

This work considers the possibility of using ring resonators as optical modulators in communication systems. Ring resonators are the major component in all-optical integrated photonic circuits due to their small size, which contributes to increasing the integration density. Controlling the light intensity through the eclectic/optic effect is the main aim of this study. Electron/optic modulation through the use of the plasma dispersion effect is studied. The plasma dispersion effect is a mechanism by which a controlled change in the effective refractive index of Silicon on Insulator (SOI) can be achieved by changing the concentration of free carriers in the silicon waveguides. In the SOI ring resonator based optical modulator, the intensity of the light passing through the resonator is controlled by changing the refractive index of the ring waveguide material, which in turn changes the resonance conditions of the resonant modes. This change in the resonance conditions can be achieved by applying an electrical field to the modulating electrodes, which are placed in the rib waveguide. In this work, the theoretical analysis and the response of the modulator are first presented, then the performance is validated using 3D simulation software. Although the work concentrates more on the intensity modulation of On-Off keying, it also opens the door for using such compact modulators for different modulation techniques such as Orthogonal Frequency Division Multiplexing (OFDM); which means high data rate modulators using small-size devices.