Distributed feedback lasers emitting in a stable dynamic single mode at 1.5 &mgr;m wavelength in a temperature range of more than 50 °C have been developed using the so‐called flat‐surface buried heterostructure. Threshold currents as low as 14 mA in cw (8 mA in pulse) operating and output powers as high as 20 mW/facet were obtained. By detuning the Bragg wavelength to the shorter wavelength side of the gain peak, and by reducing the confinement factor, a wavelength chirp as a function of modulation current as low as 0.003 nm/mA has been obtained. This value corresponds to a total chirp of 0.1–0.2 nm under normal modulation conditions.