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Proceedings Paper

Mechanisms and point defects responsible for the formation of gray tracks in KTP
Author(s): Larry E. Halliburton; Michael P. Scripsick
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Paper Abstract

The formation of gray tracks in KTP is initiated when a Nd:YAG laser produces above-band-gap photons which, in turn, create electron-hole pairs along the beam path through the crystal. These photons result from nonlinear processes (e.g., tripling of the fundamental beam, sum- frequency generation with a fundamental and a doubled beam, etc.). These processes will create 355-nm photons which, coincidentally, nearly match KTP's room-temperature band edge at 350 nm. Many of these electrons and holes produced by above-band-gap photons will recombine; however, a portion of them will be trapped at stabilizing entities such as vacancies or impurities and form 'stable' gray tracks. In the present work, x-rays are used to simulate the effects of an intense laser beam, and thus increase the total number of centers within the sample that are available for study with electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) techniques. In flux-grown KTP crystals, holes are trapped at trivalent iron (Fe3+) ions, thus forming Fe4+ centers, and electrons are trapped on titanium ions having an adjacent oxygen vacancy, thus forming Ti3+-VO centers. At room temperature, the decay of these electron and hole traps has a half-life of approximately 2 hours. Optical absorption bands associated with these electron and hole traps give rise to the gray- track color.

Paper Details

Date Published: 10 April 1995
PDF: 10 pages
Proc. SPIE 2379, Solid State Lasers and Nonlinear Crystals, (10 April 1995); doi: 10.1117/12.206476
Show Author Affiliations
Larry E. Halliburton, West Virginia Univ. (United States)
Michael P. Scripsick, Crystal Associates (United States)

Published in SPIE Proceedings Vol. 2379:
Solid State Lasers and Nonlinear Crystals
Gregory J. Quarles; Leon Esterowitz; Lap Kin Cheng, Editor(s)

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