Modeling of Strain Induced Pockels Effect in Silicon Photonic Waveguides

Abstract

Linear phase modulation is a critical characteristic of state-of-the-art modulators in coherent optical communication systems. Currently the majority of silicon modulators being developed are based on the plasma dispersion effect since silicon's centrosymmetric crystal structure prohibits the Pockels (or linear electro-optic) effect. The plasma dispersion effect is nonlinear with speed limited by charge mobility. Recently it was shown that by applying an anisotropic strain to silicon waveguides, the symmetry of the crystal structure can be broken, hence, artificially inducing the Pockels effect. In this dissertation we investigate the strain induced Pockels effect in silicon waveguides. We introduce a Figure of Merit (FOM) that characterizes the Pockels effect in various silicon waveguides and show the proposed FOM has an excellent correlation with the experimentally obtained second order nonlinearity χ(2). A six-fold improvement of FOM can be achieved by optimizing the waveguide cross-section and tuning the mechanical properties of the straining layer.