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Proceedings Paper

Near-ultraviolet absorption-annealing effects in HfO2 thin films subjected to continuous-wave laser irradiation at 355 nm
Author(s): S. Papernov; A. A. Kozlov; J. B. Oliver; T. J. Kessler; B. Marozas
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Paper Abstract

Hafnium oxide is the most frequently used high-index material in multilayer thin-film coatings for high-power laser applications ranging from near-infrared to near-ultraviolet. Absorption in this high-index material is also known to be responsible for nanosecond-pulse laser-damage initiation in multilayers. In this work, modification of the near-ultraviolet absorption of HfO2 monolayer films subjected to irradiation by continuous-wave (cw) 355-nm or 351-nm laser light focused to produce power densities of the order of ~100 kW/cm2 is studied. Up to a 70% reduction in absorption is found in the areas subjected to irradiation. Temporal behavior of absorption is characterized by a rapid initial drop on the few-tens-of-seconds time scale, followed by a longer-term decline to a steady-state level. Absorption maps generated by photothermal heterodyne imaging confirm the permanent character of the observed effect. Nanosecond-pulse, 351-nm and 600-fs, 1053-nm laser-damage tests performed on these cw laser-irradiated areas confirm reduction of absorption by measuring up to 25% higher damage thresholds. We discuss possible mechanisms responsible for near-ultraviolet absorption annealing and damage-threshold improvement resulting from irradiation by near-ultraviolet cw laser light.

Paper Details

Date Published: 19 November 2013
PDF: 7 pages
Proc. SPIE 8885, Laser-Induced Damage in Optical Materials: 2013, 888504 (19 November 2013); doi: 10.1117/12.2031640
Show Author Affiliations
S. Papernov, Univ. of Rochester (United States)
A. A. Kozlov, Univ. of Rochester (United States)
J. B. Oliver, Univ. of Rochester (United States)
T. J. Kessler, Univ. of Rochester (United States)
B. Marozas, Cornell Univ. (United States)

Published in SPIE Proceedings Vol. 8885:
Laser-Induced Damage in Optical Materials: 2013
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; MJ Soileau, Editor(s)

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