Measured and modeled conducted susceptibility characteristics of a lithium niobate electrooptic modulator

The electromagnetic (EM) susceptibility of an electrooptic (E-O) modulator is characterized. A nonlinear susceptibility model and measured results are presented for a Crystal Technology MZ385P optical guided-wave intensity modulator. The transfer function for the E-O modulator is expressed in closed form and a Bessel function expansion of this transfer function is used to predict nonlinear effects. The nonlinear effects which are modeled include gain compression, radiant power offset, harmonic generation, and intermodulation generation. The model predictions are compared to measured data at in-band and out-of-band frequencies. At in-band frequencies, excellent agreement is obtained between measured and modeled nonlinear product levels. At out-of-band frequencies, variations in the nonlinear output product levels are explained by the frequency-dependent gain characteristics of the modulator