Divergence temporal dynamics of a Q-switched laser

I address the influence of the direct coupling of the average lattice strains to the active ions on the pulse shape and the far-field beam spreading of a Q-switched laser. Calculations are made for the Cr(3+): sapphire system. The dynamic behavior of laser divergence as the pulse develops is studied without and with an internal aperture. The results can be used to search for similar effects in lasers involving other ions, such as Ti(3+) and Cr(4+).