We have demonstrated the generation and transmission of 10-Gbaud optical 3/4-return-to-zero differential quadrature phase-shift-keying (3/4-RZ-DQPSK) signals using a chirp-managed distributed-Bragg-reflector (DBR) laser (CML), without requiring any differential encoder or external modulator. We realized error-free transmission in 60-km standard single-mode fiber without any dispersion compensation. No optical signal-to-noise ratio penalty was induced. We also investigated the impact of different optical spectrum reshaper filters in CML on the transmission performance. The tolerance against the amplitude fluctuation of the electrical driving signal was also studied.