MMI combiner integrated 4 × 50 Gb/s array of directly modulated 1.3 µm DFB lasers with MQW-based passive reflectors

We report an InP-based MMI combiner integrated array of 4 channel directly modulated 1.3 µm distributed feedback (DFB) lasers. Each laser channel in the array has an active DFB section and a passive distributed Bragg reflector (DBR) section. Both sections have the same InGaAlAs multi-quantum wells (MQWs) and the same grating pitch, which simplify the device design and fabrication. The 3 dB direct modulation bandwidth is larger than 28 GHz for all four channels. 25 Gb/s NRZ and 50 Gb/s PAM4 data modulations on each channel are demonstrated. The reported device is a promising low-cost monolithic light source for high capacity WDM optical communication systems.