Laser-induced damage as a function of dielectric properties at 1.06 micrometers

Ten dielectric materials in half-wave optically thick films and eleven uncoated dielectric surfaces were subjected to damaging radiation from TEM sub 00 Nd(3-) in a glass laser operating at 1.06 micrometers. The threshold optical electric field for damage was determined for each thin film and uncoated surface. It was demonstrated that the root mean square surface roughness was important in determining the threshold field for roughness ranging from nearly 1,000 A (rms) to less than 10 A (rms). The basic relationship between damage threshold and surface roughness held both for the bare surfaces and for the thin films placed on surfaces with varying roughness. A theoretic-empirical formula was developed which is used to predict threshold fields as a function of material properties, such as refractive index and atomic number density, and surface roughness as well as thin-film material. The relationship holds for a variety of materials in bulk form as well as bare surfaces and thin-film coatings. Agreement between prediction and experiment was generally within 20 percent, the typical experimental accuracy. Previously published results were favorably compared to the predicted values.