SIMULATION AND ANALYSIS OF SILICON ELECTROOPTIC MODULATORS UTILIZING THE CARRIER-DISPERSION EFFECT AND IMPACT-IONIZATION MECHANISM

A new type of Si guided-wave electro-optic modulator is proposed and analyzed. The modulator makes use of the impact-ionization mechanism for carrier generation, and the carrier-dispersion effect for electro-optic conversion. Both electrical and wave propagation properties of the modulator were examined by a two-dimensional device simulator and a three-dimensional waveguide simulator, respectively. Numerical estimates of phase modulation due to refractive-index change and intensity modulation due to optical absorption and radiation loss were obtained. One of important features of the prospected modulator is speed. The simulated turn-on and turn-off time of the modulator was less than 1 ns. GHz modulation is, therefore, possible for this class of modulators with device structure and doping profiles optimized for fiber coupling.