Assessment of the damage threshold in sapphire crystal doped with titanium

The development of systems based on femtosecond lasers require to know with accuracy the damage threshold of sapphire crystal (Al2O3) doped with titanium (Ti:sapphire). This article is dedicated to the study of bulk and surface damaging of Ti:sapphire samples operating in femtosecond conditions. The characteristics of the laser used for the testing are the following: energy: 400 μJ, duration: 100 fs, repetition rate: 1 kHz - 100 Hz, laser beam diameter: 6 mm, and polarization: horizontal. The results show that: -) the damage threshold depends strongly on both the number of shots and on the doping levels, -) the surface damage threshold is typically in the 1 - 10 J/cm2 brackets depending on the state of the surface and on the doping whereas the values for the bulk damage threshold are 10 times higher. (A.C.)