Picosecond semiconductor lasers with an external fibre resonator

The passive mode-locking regime of multisection GaAlAs heterostructure laser diodes has been studied. Pieces of single-mode optical fibres with an edge nonselective mirror or a fibre Bragg grating have been used as an external cavity. Regular trains of optical pulses a few picosecond long and with a peak power of a few watts have been obtained under dc current injection. Spectral characteristics of the pulses are crucially dependent on the parameters and adjustment of the external cavity.