A full 3D model of the modulation efficiency of a submicron complementary metal–oxide–semiconductor (CMOS)-compatible interleaved-junction optical phase shifter

The optimization of the performance of optical modulators requires reasonably accurate predictive models for key figures of merit. The interleaved PN junction topology offers the maximum mode/junction overlap and enables the most efficient modulators for depletion-mode operation. Due to the structure of such devices, accurate modeling must be fully three dimensional (3D), representing a nontrivial computational problem. A rigorous 3D model for the modulation efficiency of a silicon-on-insulator interleaved-junction optical phase modulator with submicron dimensions is presented herein. The drift–diffusion and Poisson’s equations are solved on a 3D finite-element mesh, while Maxwell’s equations are solved using the finite-difference time-domain method on 3D Yee cells. The entire modeling process is presented in detail, and all the coefficients required by the model are presented. The model validation suggests < 10% root-mean-square (RMS) error.