Bandwidth-limited picosecond pulse generation by hybrid mode-locking in a ring cavity GaAlAs laser

Abstract

Bandwidth-limited picosecond pulses have been obtained using hybrid active/passive mode-locking in an external cavity semiconductor diode ring laser. Active mode-locking by application of sinusoidal RF modulation at the cavity round-trip frequency to a diode laser providing gain is supplemented by passive mode-locking in a second laser which is biased to provide saturable loss. Simultaneous streak camera and scanning Fabry-Perot interferometer measurements show that bandwidth-limited pulses of 25 Ps duration are obtained. Operation is not limited to near laser threshold, and frequency detuning sensitivity is improved when compared to the case of purely active mode-locking.