Abstract

We have performed measurements and simulations which identify self-focusing of random temporal intensity spikes as an important mechanism causing optical damage in a diode-pumped, Q-switched Nd:YAG laser. The average pulse power is much lower than that required to cause significant self-focusing. However, since the laser is oscillating on multiple longitudinal modes, random intensity spikes are sometimes sufficiently strong to cause catastrophic self-focusing after several round trips in the resonator. Experimental observations of these effects will be discussed. A simulation program for the laser has been developed, and this can compute how the probability of catastrophic self-focusing depends on the experimental conditions. The simulation results agree well with experimental observations.

© 1997 Optical Society of America