Role of HfO₂/SiO₂ thin-film interfaces in near-ultraviolet absorption and pulsed laser damage

Journal Article · Fri Jul 15 00:00:00 EDT 2016 · Optical Engineering

DOI:https://doi.org/10.1117/1.OE.56.1.011004· OSTI ID:1278446

Papernov, Semyon ^[1]; Kozlov, Alexei A. ^[1]; Oliver, James B. ^[1]; Smith, Chris ^[1]; Jensen, Lars ^[2]; Guenster, Stefan ^[2]; Maedebach, Heinrich ^[2]; Ristau, Detlev ^[2]

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1. Univ. of Rochester, Rochester, NY (United States)
2. Laser Zentrum Hannover e.V., Hannover (Germany)

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 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-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 HfO₂ film in both sputtered and evaporated coatings. The results are explained through the similarity of interfacial film structure with structure formed during the codeposition of HfO₂ and SiO₂ materials.

• Research Organization: Univ. of Rochester, NY (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: NA0001944
• OSTI ID: 1278446
• Journal Information: Optical Engineering, Vol. 56, Issue 1; ISSN 0091-3286
• Publisher: SPIE
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
thin films
interfaces
absorption
laser damage