Predistortion for High-Speed Lumped Silicon Photonic Mach-Zehnder Modulators

The use of electrical precompensation for high-speed operation of lumped MZMs is demonstrated for 50 Gb/s PAM4 modulation through experiment and simulation. An accurate equivalent circuit model is fitted to S11 measurements and then used to analyse design trade-offs in terms of system performance, energy consumption and drive voltage requirements. If precompensation is not used, careful selection of source resistance with respect to electrode and packaging inductance is shown to be crucial for high-speed modulation. Increasing the electrode inductance is shown to be beneficial as it introduces inductive peaking, which allows optimum performance with a higher source impedance. Furthermore, combining precompensation with a slight inductive peaking and optimised source resistance is demonstrated to reduce drive voltage requirements and further reduce the energy dissipated in the equivalent circuit.