Modeling and Experiment Verification of Lateral Current Spreading Effect in Ridge Waveguide Electroabsorption Modulators

We investigate the lateral current spreading effect and its influences on the transmission characteristics of ridge waveguide electroabsorption modulators. An RF equivalent circuit based on a transmission line model explicitly accounting for this effect is proposed. The equivalent circuit parameters in our model extracted from S-11 curve fitting are used to simulate the S-21 response (electro-optical response (E/O) response), which matches well with the measured direct S-21 small-signal modulation response. The physical significance of our model parameters can be well explained based on the secondary ion mass spectroscopy doping profiling and the simulation of the current spreading effect in our device structure.