Actively mode-locked external-cavity semiconductor lasers with transform-limited single-pulse output

We describe the use of split-contact semiconductor laser diodes to suppress multiple-pulsing phenomena in actively mode-locked external-cavity lasers. The laser-diode length is critical for the elimination of multiple-pulse output. With a grating installed in the external cavity, 11.5-ps pulses are generated that have a time–bandwidth product of only 0.30, an important property for use in soliton transmission systems. By using a broadband mirror in place of the grating, nearly transform-limited single pulses of 1.4-ps duration are generated at a 3-GHz repetition rate.