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Title: The role of film interfaces in near-ultraviolet absorption and pulsed-laser damage in ion-beam-sputtered coatings based on HfO2/SiO2 thin-film pairs

The role of thin-film interfaces in the near-ultraviolet absorption and pulsed-laser–induced damage was studied for ion-beam–sputtered and electron-beam–evaporated coatings comprised from HfO2 and SiO2 thin-film pairs. To separate contributions from the bulk of the film and from interfacial areas, absorption and damage-threshold measurements were performed for a one-wave (355-nm wavelength) thick, HfO2 single-layer film and for a film containing seven narrow HfO2 layers separated by SiO2 layers. The seven-layer film was designed to have a total optical thickness of HfO2 layers, equal to one wave at 355 nm and an E-field peak and average intensity similar to a single-layer HfO2 film. Absorption in both types of films was measured using laser calorimetry and photothermal heterodyne imaging. The results showed a small contribution to total absorption from thin-film interfaces, as compared to HfO2 film material. The relevance of obtained absorption data to coating near-ultraviolet, nanosecond-pulse laser damage was verified by measuring the damage threshold and characterizing damage morphology. The results of this study revealed a higher damage resistance in the seven-layer coating as compared to the single-layer HfO2 film in both sputtered and evaporated coatings. Here, the results are explained through the similarity of interfacial film structure with structure formed duringmore » the co-deposition of HfO2 and SiO2 materials.« less
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Univ. of Rochester, Rochester, NY (United States); Laser Zentrum Hannover e.V. (Germany)
  2. Univ. of Rochester, Rochester, NY (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Proceedings of SPIE - The International Society for Optical Engineering
Additional Journal Information:
Journal Volume: 9632; Conference: Laser-Induced damage in optical materials, Boulder, CO (United States), 27 Sep 2015
Research Org:
Univ. of Rochester, Rochester, NY (United States). Lab. for Laser Energetics
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE thin films; interfaces; absorption; laser damage