Flashlamp-pumped Cr:LiSAF thin slab zig-zag laser studies

Summary form only given. We have demonstrated a flashlamp-pumped Cr:LiSAF zig-zag thin slab laser that has achieved laser output energies to 6.4 J from a single slab in a configuration capable of operation at high average power. This corresponds to an intrinsic photon efficiency of close to 35%. Tuning of the laser output from 800 to 900 nm was accomplished using an etalon with a free spectral range of 30,000 GHz. The laser bandwidth was narrowed to about 160 GHz (from a free-running bandwidth of about 250 GHz) and the laser output decreased by about a factor of 2. Further bandwidth control was demonstrated near the peak of the gain, around 830 nm, using three intracavity etalons with free spectral ranges of 30,000 GHz, 5,000 GHz, and 200 GHz, respectively. A bandwidth narrowed output of 8 GHz was observed. Beam quality was measured for the laser operating singly. The short, 40-ns Q-switched pulses resulted in beam qualities of about 2.2 XDL. It appears that the Q-switched pulse lengths did not provide adequate build-up time to form a good low-order mode. Better beam quality was observed in a free-running operating regime where longer pulses occurred. Under these operating conditions a beam quality of 1.35 times the diffraction limit was achieved.