Mode-locked fiber lasers based on semiconductor saturable absorbers

This paper reviews recent progress in ultrashort pulse generation with mode-locked fiber lasers utilizing semiconductor saturable absorbers to initiate the mode-locking mechanism and to stabilize the laser pulse train. The saturable absorbers were monolithically grown by molecular beam epitaxy on top of a Burstein-Moss shift Ga0.47In0.53As /InP distributed Bragg reflector. The design guidelines and the main features of the semiconductor saturable absorber mirrors are summarized. Synchronization of a harmonically mode-locked pulse train to an external signal and repetition rate stabilization is demonstrated by directly modulating the 980 nm pump diode laser used both to provide gain and to optically modulate a semiconductor saturable absorber mirror.