A novel technique is used to produce picosecond wavelength-tunable optical pulses from gain-switched Fabry-Perot semi-conductor lasers using fibre compression. Experiments are carried out with high power, large modulation-bandwidth lasers at 1.3-mu-m. Pulses of 2.5 ps durations with repetition rates up to 12 GHz are obtained. Still shorter pulses (approximately 1 ps) with higher repetition rates (18 GHz) are shown to be feasible.