Ultrashort pulses in diffraction-limited beam from diode laser arrays with external cavity

Picosecond pulses are generated in a diffraction-limited beam from passive (hybrid) modelocked conventional ( lambda =0.8 mu m) diode laser arrays in an external cavity. The emitted energy (10-20 pJ) is almost one order of magnitude higher than that obtained from single stripe quantum well lasers at similar pulse durations. The shortest pulses ( approximately 3 ps, 3 nm spectral width) are obtained with strong saturable absorbers and 1% antireflection coatings. Correspondingly, external cavities with relatively low angular selectivity can be used in these conditions.