Transmission of 100 Gb/s PAM4 Data Using a Low Cost Directly Modulated DFB Laser

In this letter, we report transmissions of 100 Gb/s PAM4 data using a low-cost high bandwidth directly modulated $1.3~\mu $ m distributed feedback (DFB) laser. In the device, a passive distributed Bragg reflector (DBR) section is integrated, which leads to a 29 GHz modulation bandwidth at $20~^{\circ }$ C. The DFB and DBR sections of the device have the same InGaAlAs multi-quantum wells (MQWs). This simplifies the device fabrication process notably, which is similar to a conventional DFB laser. At $20~^{\circ }$ C, the threshold current of the device is 14 mA and the maximum optical power for the laser is larger than 16 mW. At 100 Gb/s PAM4 data modulation, clear eye diagrams have been obtained for back-to-back and up to 40 km single mode fiber transmissions.