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Title: Role of HfO 2/SiO 2 thin-film interfaces in near-ultraviolet absorption and pulsed laser damage

Here, the role of thin-film interfaces in the near-ultraviolet (near-UV) absorption and pulsed laser-induced damage was studied for ion-beam-sputtered and electron-beam-evaporated coatings comprised from HfO 2 and SiO 2 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, HfO 2 single-layer film and for a film containing seven narrow HfO 2 layers separated by SiO 2 layers. The seven-layer film was designed to have a total optical thickness of HfO 2 layers, equal to one wave at 355 nm and an E-field peak and average intensity similar to a single-layer HfO 2 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 HfO 2 film material. The relevance of obtained absorption data to coating near-UV, 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 HfO 2 film in both sputtered and evaporated coatings. The results aremore » explained through the similarity of interfacial film structure with structure formed during the codeposition of HfO 2 and SiO 2 materials.« less
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  1. Univ. of Rochester, Rochester, NY (United States)
  2. Laser Zentrum Hannover e.V., Hannover (Germany)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Optical Engineering
Additional Journal Information:
Journal Volume: 56; Journal Issue: 1; Journal ID: ISSN 0091-3286
Research Org:
Univ. of Rochester, Rochester, NY (United States)
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE; thin films; interfaces; absorption; laser damage
OSTI Identifier: