Flat bottom pits, previously shown to be unstable above a critical fluence, may be impacted by interfacial characteristics of the multilayer. TEM cross-sections reveal multilayer coatings deposited from hafnium have fewer interfacial voids than those deposited from hafnia. To correlate this reduction with the occurrence of flat bottom pits, multilayer high reflectors deposited by reactive electron-beam evaporation form both metallic and oxide sources were damage tested with 3-ns, 1064-nm pulses. To shift the electric-field peaks to the adjacent interface, half of the sample included an additional buried half-wave of silica in their all quarter-wave design. All quarter-wave reflectors deposited from hafnia had flat bottom pit damage in the outer six layers at fluences of 20 J/cm2. Interfacial damage also occurred in hafnium deposited coatings at fluences as low as 20 J/cm2, but at significantly different depths. The only interfacial damage observed on the all quarter-wave coatings was at the substrate multilayer interface. Flat bottom pits were observed in the buried half-wave coatings with a correlation to electric-field position and preference to interface type.
[1]
Francois Y. Genin,et al.
Morphologies of laser-induced damage in hafnia-silica multilayer mirror and polarizer coatings
,
1996,
Other Conferences.
[2]
Francois Y. Genin,et al.
Growth of laser-induced damage during repetitive illumination of HfO2/SiO2 multilayer mirror and polarizer coatings
,
1997,
Laser Damage.
[3]
Jean DiJon,et al.
Nano absorbing centers: a key point in the laser damage of thin films
,
1997,
Laser Damage.
[4]
Mark R. Kozlowski,et al.
Laser conditioning methods of hafnia silica multilayer mirrors
,
1998,
Photonics West.
[5]
Etienne Quesnel,et al.
Thin film laser damage mechanisms at the YAG third harmonic
,
1996,
Laser Damage.