ELECTROOPTIC MODE-DISPLACEMENT SILICON LIGHT-MODULATOR

A new type of guided-wave electro-optical intensity modulator is proposed and analyzed. The waveguide consists of an N-type Si core layer on a P-type Si substrate. Foward bias on the N+-N-P-P+ diode decreases the refractive index of the core and displaces the fundamental guided mode downward into the substrate. However, the mode is not extinguished because the substrate is bounded by a P+ contact. A spatial filter at the output converts the mode displacement into optical intensity modulation. A Poisson and continuity equation solver and multilayer waveguide simulation were used to obtain numerical estimates of mode displacement in a realistic structure.