Generation of Return-to-Zero Optical Pulses Using Directly Modulated Chirp Managed Laser

We propose and experimentally demonstrate the generation of return-to-zero (RZ) optical pulses with duty cycles of 33% and 67% using a directly modulated chirp managed laser (CML) driven by a sinusoidal signal at half pulse rate. No external pulse carver is required. The transmission performance of a 10-Gb/s RZ differential phase-shift keying (RZ-DPSK) signal based on CML pulses is also investigated. It shows comparable fiber chromatic dispersion tolerance and fiber nonlinearity robustness in single-channel test, compared with the conventional RZ-DPSK signal generated, via an external pulse carver.