Research on the single and multiple pulse laser damage performance of UV anti-reflection coatings

Multiple-pulse laser-induced damage is an important topic for many applications of optical coatings. In this work, we study the performance of multiple and single pulse laser-induced damage of anti-reflection (AR) coatings with ns-pulsed laser irradiation at a wavelength of 355 nm. LIDT of AR coatings changes little under multiple and single pulse irradiation, around 15 J/cm(2). The damage probability curve of multiple pulse is extremely steep. The defect density in the irradiated area is quite high, a large amount of pin-point or cone-shaped pits are observed. The absorption coefficient and defect density increase a lot under multiple pulse irradiation. Material modification of the precursor under multiple pulse is thought as the main reason of high absorption coefficient. Once damage occurs, the damage increases fast and soon grows catastrophic damage. The initial damage morphologies are similar, pin-point or cone-shaped pits, which indicates the initial precursor or defect of multiple and single pulse are the same.