A 1.3-\mu m wavelength vertical-mesa ridge waveguide mulitple-quantum-well (MQW) distributed feedback (DFB) laser with high directly modulated bandwidth and wide operation temperature range is reported. With the optimization of the strained-layer MQWs in the active region, the surrounding graded-index separated-confinement-heterostructure waveguide layers, together with the optimization of the detuning and coupling coefficient of the DFB grating, high directly modulation bandwidth of 16 GHz at room temperature and wide working temperature range from ?40 to 85 \circ C are obtained. The mean time to failure (MTTF) is estimated to be over 2×10<sup>6</sup> h. The device is suitable as light source of high-bit-rate optical transmitters with small size and reduced cost.