Time-Domain Electromagnetic Modeling and Simulation of a Nonlinear Electro-Optical Mixer

A full-wave electromagnetic solver coupled with a Poisson’s solver based on time-domain finite element method (TD-FEM) is developed. This solver aims to simulate the side-band frequency generation on optical signal due to the imposed radio frequency (RF) signal through a nonlinear material. The optical signal propagating within an optical waveguide is simulated in time-domain by solving the electromagnetic wave equation, whereas Poisson’s equation is numerically solved to compute the strength of the slowly-varying RF signal. The applied RF signal changes the permittivity of the nonlinear material BTO, and this changing permittivity affects the transient wave behavior of the light. As opposed to the available frequency-domain Maxwell solvers, this proposed time-domain solver is capable of simulating the nonlinear effects introduced by an electro-optical material, and implemented for the modeling of an application where RF signal is mixed into the optical frequencies. As a result of the simulations, nonlinear dielectric constant of electro-optical material is computed, and resulting side-band frequency generation is observed in the spectrum of the time-domain output signal.