Studies of laser damage morphology reveal subsurface feature in fused silica

Abstract

AbstractWe present a detailed study of the morphology of 355 nm (6 ns) laser‐induced damage in fused silica polished by CeO2 solution. We see two distinct damage morphologies: the gray haze and the crater. The gray haze, consisting of a high density of pin‐points, appears at the fluence higher than ∼10 J/cm2, and the crater forms at ∼≥ 22 J/cm2. The size and depth of the pin‐points are much smaller than the crater. The difference in the two morphologies is attributed to the property of the absorber and its surrounding material in the redeposition layer, which is different from those in the subsurface damage layer. The damage growth characteristics of the two morphologies are measured, and the size of crater increases under successive shots, but the size of the gray haze remains constant. The growth of the crater is attributed to the existence of crack around the absorber, which is observed by SEM imaging. On the basis of the above analysis, the schematic diagram of subsurface feature is discussed. Copyright © 2010 John Wiley & Sons, Ltd.