Generation of transform-limited picosecond pulses at 1.0 µm from a gain switched semiconductor laser diode

We report the generation of short, transform-limited, ~18 ps optical pulses from an external fiber Bragg grating (FBG) stabilized semiconductor laser diode. Up to 7.2 pJ of pulse energy and a peak power of 400mW were achieved when operating at a repetition frequency of 832.6 MHz, a multiples of the cavity round trip frequency. A small detuning in the repetition frequency resulted in broader optical pulses. We have shown experimentally that an active mode-locking rather than gain switching mechanism is behind the generation of transform limited optical pulses at the optimum operating frequency