Transform-limited 480 GHz colliding-pulse modelocked laser diode

Generation of a 480 GHz optical pulse train from a short-cavity colliding-pulse modelocked laser diode is reported. Cavity loss reduction by high-reflection coatings of both laser facets was found to be effective for pulse shortening. The pulsewidth of the laser output was 0.52 ps and the time-bandwidth product was 0.31, indicating that the laser output was nearly transform-limited.