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Proceedings Paper

Identification of point defects responsible for laser-induced ultraviolet absorption in LiB3O5 (LBO) crystals
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Paper Abstract

Electron paramagnetic resonance (EPR) has been used to identify and characterize point defects in lithium triborate (LiB3O5) crystals grown for nonlinear optical applications. As-grown crystals contain oxygen vacancies and lithium vacancies (as well as trace amounts of transition-metal ions in a few samples). Exposing a crystal to ionizing radiation at 77 K produces “free” electrons and holes. These electrons are trapped at the pre-existing oxygen vacancies and give rise to an EPR signal with a large hyperfine from one 11B nucleus. The corresponding holes become self-trapped on oxygen ions as a result of the significant lattice relaxation of a nearest-neighbor fourfold-bonded boron ion. This gives rise to an EPR signal with a smaller 11B hyperfine pattern due to the oxygen’s threefold bonded boron neighbor. Warming the crystal to approximately 130 K destroys the self-trapped hole centers that were initially formed, and allows a second holelike signal to be observed (which in turn decays between 150 and 200 K). The structure of the second hole center is very similar to the self-trapped hole center and a neighboring lithium vacancy makes this latter center more thermally stable. The EPR spectra from Ni+ and Cu2+ ions are also reported.

Paper Details

Date Published: 30 May 2003
PDF: 10 pages
Proc. SPIE 4932, Laser-Induced Damage in Optical Materials: 2002 and 7th International Workshop on Laser Beam and Optics Characterization, (30 May 2003);
Show Author Affiliations
W. Hong, West Virginia Univ. (United States)
Nelson Y. Garces, West Virginia Univ. (United States)
M. M. Chirila, West Virginia Univ. (United States)
Larry E. Halliburton, West Virginia Univ. (United States)

Published in SPIE Proceedings Vol. 4932:
Laser-Induced Damage in Optical Materials: 2002 and 7th International Workshop on Laser Beam and Optics Characterization
Gregory J. Exarhos; Adolf Giesen; Arthur H. Guenther; Norbert Kaiser; Keith L. Lewis; Horst Weber; M. J. Soileau; Christopher J. Stolz, Editor(s)

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