Laser damage resistance of silica thin films deposited by Electron Beam Deposition, Ion Assisted Deposition, Reactive Low Voltage Ion Plating and Dual Ion Beam Sputtering

The laser damage resistance of optical coatings is a key point for a large number of applications. The aim of this work is to test and analyze the laser damage resistance of a thin film material commonly used for high power applications (SiO2) and deposited with different techniques: Electron Beam Deposition, Ion Assisted Deposition, Low Voltage Reactive Ion Plating and Dual Ion Beam Sputtering. The laser damage thresholds of these coatings were determined at 1064 nm and 355 nm using nanosecond pulsed YAG lasers, with a 1-on-1 test procedure. The results are then compared and discussed: we found different behaviours that we link to laser damage initiators of different nature and densities. The dense thin films (obtained with ion assistance) were found to be highly resistant to laser damage.