Full-vectorial finite difference for optical analysis of travelling wave electroabsorption modulators

A full-vectorial finite-difference-based optical mode solver is presented to analyze travelling wave electroabsorption modulator (TWEAM). The discontinuities of the normal components of the electric field across abrupt dielectric interfaces are considered in this analysis which in contrast is the limitations of scalar and semivectorial approximation method. The optical field distributions in a ridge-type traveling-wave coplanar waveguide (CPW) electroabsorption modulator for 1.55 mum operation are presented. The important parameters in the high-frequency TWEAM design such as optical effective index which defines optical velocity and transverse mode confinement factor are calculated. Then, the effects of microwave and optical properties of waveguides on modulation response of TWEAMs are analyzed.