10 Gb/s NRZ and 20 Gb/s PAM4 Transmission Using an EAM-Integrated Widely Tunable DBR Laser

We report data transmissions using a widely tunable InP-based distributed Bragg reflector (DBR) laser integrated monolithically with an electroabsorption modulator (EAM). The laser has a wavelength tuning range of over 12 nm that is obtained by current injection into the DBR section because the butt-jointed InGaAsP DBR material has a long bandgap wavelength. Data transmissions of 10 Gb/s nonreturn to zero (NRZ) at distances of up to 75 km of a single mode fiber have been demonstrated. A power penalty of less than 0.9 dB has been obtained when compared to the BtB condition. In addition, transmissions of 20 Gb/s four-level pulse amplitude modulation (PAM4) data at distances of up to 45 km have been conducted successfully. These results indicate that the EAM-modulated DBR laser is promising for long-reach low-cost WDM optical network applications.