Subpicosecond pulses from passively mode‐locked GaAs buried optical guide semiconductor lasers

We report the observation of bursts of transform‐limited 0.65‐psec pulses at 1‐GHz repetition rates by passive mode locking of a buried optical guide laser in an external cavity. The lasers contain a saturable absorber at the exit facet, specifically introduced by 600‐keV proton bombardment at a 3×1015‐ cm−2 dosage level.