Real-time Simulation of the Nonlinear Distortion of Coupled Channel/Interferometric Modulator Designs

Practical analytic representations of modulator designs are available for only the simplest cases such as the Mach-Zehnder interferometer and the directional coupler. The low frequency dynamic response of the fundamental and nonlinear signals of these modulators are usually described according to their Taylor expansions [1]. However, the frequency response of the fundamental signal for even a simple directional coupler has yet to be expressed in closed form. For modulator designs that are more complex, analytic expressions for the low frequency intensity response are themselves quite complicated, providing little insight into device performance or design optimization. The effect of the RF frequency on the modulator performance (especially the nonlinear distortion) is typically ignored.