Experimental Study of a Flash-lamp Pumped Passively Q-Switched Nd:YAG Laser Using Cr4+:YAG Saturable Absorber

This paper deals with the experimental results of a xenon flash-lamp pumped passively Q-switched Nd:YAG laser using Cr4+:YAG saturable absorber. The need of a laser cavity to be integrated into a time-of-flight laser range finder is of great interest as an experimental investigation of several laser resonators. Two types of laser resonator, with different lengths, have been studied: the flat-flat and plano-concave ones. Each laser cavity consisted of a flat output coupler, characterized by its reflectivity, and combined with a high reflectivity mirror, allowed the observation of the laser output characteristics. It has been demonstrated that the radius of curvature, of the high reflectivity mirror, is of great importance in determining the best laser performances. The best results were achieved using a flat-flat cavity of 18.5 cm in length, electrical pump energy of 21 J, and an output coupler reflectivity of 50%. The output laser energy was 28.4 mJ for a pulse width of 38 ns. Multiple laser pulses were also obtained, by increasing the electrical pump energy or through adjusting the laser resonator alignment.