Deterministic single shot and multiple shots bulk damage thresholds for doped and undoped crystalline and ceramic YAG

Abstract

We used 9.9-ns, single-longitudinal-mode, TEM00 pulses tightly focused to an 8-micron radius spot to measure single-shot and multiple-shot damage thresholds of pure and Nddoped ceramic Yttrium Aluminum Garnet (YAG), and of pure, Nd-doped, Cr-doped, and Yb-doped crystalline YAG. By tightly focusing the laser beam, we kept the damage threshold powers below the SBS threshold, and minimized the effect of self focusing. The size of the focus spot was measured using surface third harmonic generation. We found both single-shot and multiple-shot damage thresholds to be deterministic. At the single-shot damage threshold in YAG, breakdown always occurs on the trailing edge of the laser pulse. However, for multiple-shot damage threshold, breakdown occurs at the peak of the n^th laser pulse. Our measured damage thresholds for doped and undoped, ceramic and crystalline YAG range from 1.1 to 2.2 kJ/cm². We also report some damage morphologies in crystalline YAG.