A kind of laser diode with high power and short duration is described in this paper. The laser diode is used for triggering gallium arsenide photoconductive semiconductor switch (GaAs PCSS) in the experiment. The driver of the laser diode is based on RF MOSFET and it provides an ultra-fast pulse current, which has the rise-time, FWHM and peak current are 4ns, 17ns and 130A, respectively. The characteristics of the laser diode have been researched, including laser pulse waveform, optical field distribution, and limiting drive current. Using a combination of two laser diodes, the PCSS has a better performance than being triggered by single laser diode in the experiment.