Microwave model for optimizing electro-optical modulation response of the Mach-Zehnder modulator

A model is created to study the role of impedance matching in indium phosphide modulators. The frequencydependent characteristic impedance and propagation constant of the electrical transmission line structure is calculated from the cross-section of the phase modulator, electrode geometry, and p-i-n junction. The impedance and propagation constant are used in combination with a closed-form approximation for the traveling wave electrode and electrical circuit to create the non-iterative compact model. It yields good agreement with the experiment in a 50 Ohm measurement environment and the effect of changing source and termination impedance has been modeled. The 3dB optical modulation bandwidth is predicted to increase from 30GHz to 60GHz with optimized impedance matching and the associated suppression of electrical reflections.