Three-Dimensional FDTD Simulation of Nonlinear Ferroelectric Materials in Rectangular Waveguide

Nonlinear transmission lines have numerous applications in the communications and defense industries due to their ability to form and propagate short-duration ultrawideband pulses. This paper simulates a short-duration Gaussian transient exciting low-order TEm,0 modes in a nonlinear ferroelectric-filled conducting waveguide. A 3-D finite-difference time-domain simulation is employed in the analysis, and the ferroelectric-filled waveguide model is based on a nonlinear polarization relationship extrapolated from measurements. A small portion of the frequency band operates in the nonlinear polarization region. These components will propagate at higher velocity than lower amplitude components, and this effect counteracts dispersion and results in compression of the pulses into solitons as they propagate.