Simulation and analysis of a high-efficiency silicon optoelectronic modulator based on a Bragg mirror

We describe the operating principle of a silicon optoelectronic modulator based on the plasma dispersion effect used in conjunction with a distributed Bragg reflector, which converts the phase shift, induced by the free carriers injected by a P-i-N diode, into variations of its reflectivity. The device is integrated in a low-loss silicon-on-insulator waveguide. Two different approaches in the driving schemes are proposed. Moreover, we show how it is possible to reach a theoretical 100% modulation depth by exploiting in a concurrent way both the variations of the refractive index and the increased optical absorption. An exhaustive description of the optical structure and its guiding properties, together with the analysis of the electrical behavior of the modulator, is given. Finally, a comparison with other interferometric structures is analyzed, and it is shown how this kind of modulator exhibits satisfactory characteristics in terms of dissipated power and reduced occupation of area on a chip.