Abstract

One method for producing optical pulses as short as <20 ps FWHM with a diode laser is by gain switching. For such a laser, gain switching is readily achieved by applying an electrical (for ward bias) pulse excitation to the diode. The average duration of the resulting optical pulses depend on the detailed shape of the electrical drive pulse and the dynamic response of the laser diode (in its package) to that drive pulse. Streak camera measurements^1-2 have demonstrated that significant temporal substructure is present on the optical pulse, with subpulses of duration below 10 ps. This substructure changes dramatically from pulse to pulse. Previously reported work on gain switching of laser diodes has been almost exclusively confined to minimizing the time-averaged optical pulse duration, spectral width, and time-bandwidth product. An important additional consideration for ultrafast electro-optical sampling applications is the energy contained in the optical pulse, which should ideally be large and constant to minimize both shot noise and averaging time in the optical detection system. Little work has been done heretofore to quantify the variation in energy of diode laser optical pulses. We present here the results of a series of measurements of this energy variance in pulses produced by gain switching commercially avail able gain guided double heterostructure AlGaAs laser diodes.

© 1987 Optical Society of America