56-Gbaud 4-PAM (112-Gbit/s) operation of flip-chip interconnection lumped-electrode EADFB laser module for equalizer-free transmission

We fabricated a lumped-electrode type EADFB laser module using a flip-chip interconnection technique which provides a large modulation bandwidth. We obtained clear 56-Gbaud 4-PAM signal after 10-km SMF transmission with no equalizer using this module.