Generation of subpicosecond coherent optical pulses by passive mode locking of an AlGaAs diode laser

Abstract

Subpicosecond coherent optical pulses as short as 0.58 ps were generated for the first time by passive mode locking of an AlGaAs double heterostructure diode laser. It was realized by a simple configuration made of a conventional AlGaAs diode laser without antireflection coatings on both facets, which was aged and exhibiting self-pulsation, placed in an external cavity. When the external cavity length was shorter than about 60 mm, almost complete mode locking was observed over the oscillation spectrum of 3.5 nm in width. Based on the second-harmonic generation autocorrelation measurement, ultrashort coherent optical pulses from 0.58 to 1.2 ps in duration were demonstrated by increasing the external cavity length together with the proper control of the optical feedback effect and the pumping dc current.