Influence of the assisting-ion-beam parameters on the laser-damage threshold of SiO2 films

Silica thin films have been deposited by a dual-ion-beam sputtering techniq ue using argon or xenon ions mixed with oxygen ions in the assisting beam a nd the role of the assisting-ion-beam parameters on the laser-damage-thresh old at 308 nm (XeCl laser) has been investigated. It is shown that a proper choice of these parameters allows a considerable increase of the laser-ind uced damage threshold. Lower damage thresholds (1 J/cm(2)) were found for t he xenon/oxygen assisted samples. Whereas, the highest damage threshold (8 J/cm(2)) was found for the argon-ion assisted sample and its value was also much higher than that (2.9 J/cm(2)) of the non-assisted films. Damage thre sholds have been determined by the photoacoustic mirage technique and it is demonstrated that this technique can provide useful information on the mec hanisms responsible for laser damage. (C) 1999 Elsevier Science S.A. All ri ghts reserved.