High-power and picosecond pulse generation from a passively Q-switched tapered InGaAs/GaAs laser

Summary form only given. High-power picosecond optical pulses are required for a wide range of applications including optical switching, instrumentation, ranging, pumping, sensing, and spectroscopy. Q-switched pulses having an energy of 300 pJ and a duration of 40 ps were obtained from a 100-/spl mu/m-wide AlGaAs diode laser. However, widening the waveguide width generally results in a loss of spatial coherence. A majority of applications require both spatial and spectral coherence in the output optical pulse. Tapered waveguides have been used for enhancing pulse powers in Q-switched AlGaAs and InGaAsP (1.5 /spl mu/m) lasers. We report, for the first time to our knowledge, passively Q-switched pulses with 1.53 W peak power and 41 ps FWHM from an InGaAs/GaAs (970 nm) double-contact tapered semiconductor laser in a well defined single lobed far-field. We have fabricated the proposed two-section ridge-waveguide tapered device from an InGaAs/GaAs GRINSCH 2 QW wafer grown by MBE.