Picosecond Optical Pulse Generation from Mutually Coupled Laser Diodes by Synchronous Pump Mode-Locking

We propose and demonstrate a picosecond optical pulse generation from optically coupled laser diodes (LDs), for the first time, by synchronous pump mode-locking. Two LDs, having an antireflection coating on one facet, are mutually optically coupled, and form an external cavity (cavity length L ext ). By setting the phase difference in the modulation currents to π rad (frequency ∼ c /2 L ext ) injected into the two LDs, a pulse duration of as short as 7.2 ps is achieved with relatively high optical power (peak power ∼170 mW) from 1.3 µm InGaAsP/InP LDs.