Revisiting of the laser induced filamentation damage conditions in fused silica for energetic laser systems

The need for optics that can sustain higher laser fluences and intensities grows as new technological advancements allow laser systems to operate at increased in peak power. This has motivated a substantial effort in recent decades to study laser-induced damage mechanisms and their mitigations. One well known laser-induced damage mechanism is filamentation in fused silica glass, due to Kerr self-focusing of the light [1]. The study of filamentation has been an ongoing effort for the last few decades [2] as it turned out to be a major limitation to laser systems at high peak intensities. Past studies have led to a set of simplified rules that allows for the operation of laser system below the onset point of filamentation to occur, namely what is known as the “IL rule” (intensity times the length before filamenting equals some empirical constant) and the Bespalov-Talanov (BT) perturbation growth theory [3-8]. The necessity to increase the laser beam intensities and optimize the throughput, closer to the point where the optical propagation length in the material is comparable to the predicted filamentation distance, requires revisiting and improving our understanding of the current rule set.