112-Gbaud PAM4 Operation of Lumped-EML With 150-um EAM Length Using LC Resonance Based on Matching Resistance Optimization

We investigate the influence of a matching load resistance on frequency responses of a lumped-electro-absorption modulator-integrated lasers (EMLs) whose modulation band-widths are extended by LC resonance effect. An equivalent circuit modeling is performed to determine the optimal values of a matching load resistance enabling 112-Gbaud PAM4 operation for a lumped-EML chip with an electro-absorption modulator (EAM) length of 150 um. To verify the simulation results, we package a lumped-EML submodule and measure its high-frequency charac-teristics. Then, we experimentally demonstrate that the 3-dB bandwidth of the lumped-EML submodule can be enhanced to 55 GHz and beyond by optimizing the matching load resistance value as well as lengths of the bondwires, although the EAM length is as long as 150 um. The fabricated lumped-EML submodule exhibits clear optical eye patterns under 112-Gbaud PAM4 operation.