4$\,\times\,$25 Gb/s Frequency-Modulated DBR Laser Array for 100-GbE 40-km Reach Application

A monolithically integrated 100-Gb/s throughput (4 $\,\times\,$25 Gb/s) laser array has been developed that employs frequency-modulated distributed Bragg reflector lasers. An optical filter converts a frequency-modulated signal to an amplitude-modulated signal with a high contrast ratio in addition to reducing the lasing spectrum bandwidth. A clear eye opening after 40-km transmission was observed with a 25-Gb/s nonreturn-to-zero signal in the 1550-nm region.