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Proceedings Paper

Spontaneous and induced absorption in amorphous Ta2O5 dielectric thin films
Author(s): A. S. Markosyan; R. Route; M. M. Fejer; D. Patel; C. S. Menoni
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Paper Abstract

Tantalum pentoxide (Ta2O5) is the high index material most commonly used in optical coatings for high average-power lasers since high density sputtered oxide films with absorption losses at mid-infrared wavelengths of less than 1 ppm can be obtained. We have chosen this 'model' oxide to investigate the spontaneous and optically induced absorption at λ = 1064 nm by photothermal common-path interferometric (PCI) technique. This technique is capable of detecting sub-ppm levels of optical absorption and its changes at a given wavelength when a second beam is also incident on the thin film oxide sample. In this work dual beam experiments are implemented to assess changes in the optical absorption at λ = 1064 nm Ta2O5 thin films deposited on fused silica with accompanying electromagnetic radiation with wavelengths ranging from 266 nm to 780 nm. The accompanying radiation was found to have a substantial impact on the optical absorption at 1064 nm. The effect is associated with various electron traps existing in the forbidden gap and depends essentially on the film's preparation conditions. The substantially greater effect observed in the case of 266 nm is suggested to be the result of additional excitations from the valence band involved in the process since the photon energy of 266 nm radiation is higher than the forbidden gap.

Paper Details

Date Published: 6 December 2011
PDF: 9 pages
Proc. SPIE 8190, Laser-Induced Damage in Optical Materials: 2011, 81900F (6 December 2011); doi: 10.1117/12.899217
Show Author Affiliations
A. S. Markosyan, Stanford Univ. (United States)
R. Route, Stanford Univ. (United States)
M. M. Fejer, Stanford Univ. (United States)
D. Patel, Colorado State Univ. (United States)
C. S. Menoni, Colorado State Univ. (United States)


Published in SPIE Proceedings Vol. 8190:
Laser-Induced Damage in Optical Materials: 2011
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; M. J. Soileau, Editor(s)

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