Photorefractive Damage Mechanisms in Electro-Optic Materials

Point defects in lithium niobate and related electro-optic materials have been characterized using electron paramagnetic resonance (EPR), optical absorption, thermally stimulated been used to investigate a radiation-induced trapped-hole center. This new S = 1/2 defect is stable at 77 K but thermally...

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Bibliographic Details
Main Author: Halliburton, Larry E
Format: Report
Language:English
Subjects:
ABSORPTION
ABSORPTION SPECTRA
BAND SPECTRA
BISMUTH
CATIONS
Crystallography
DEUTERIUM
DIFFUSION COEFFICIENT
DIOXIDES
DISTRIBUTION
ELECTRIC CHARGE
ELECTRON PARAMAGNETIC RESONANCE
ELECTRONS
Electrooptical and Optoelectronic Devices
ELECTROOPTICS
EXCITATION
GERMANIUM COMPOUNDS
HEATING
HOLES(ELECTRON DEFICIENCIES)
IMPURITIES
INFRARED SPECTRA
IRON
LITHIUM COMPOUNDS
LITHIUM NIOBATES
LUMINESCENCE
NUCLEI
OPTICAL MATERIALS
OPTICAL PROPERTIES
Optics
OXIDES
OXYGEN
PE61102F
POINT DEFECTS
REFRACTION
SILICON DIOXIDE
SOURCES
TANTALUM COMPOUNDS
VACANCIES(CRYSTAL DEFECTS)
WUAFOSR2305B1
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Summary:Point defects in lithium niobate and related electro-optic materials have been characterized using electron paramagnetic resonance (EPR), optical absorption, thermally stimulated been used to investigate a radiation-induced trapped-hole center. This new S = 1/2 defect is stable at 77 K but thermally decays near 150 K. Its EPR spectrum exhibits a complex hyperfine equally with three 93 Nb nuclei. We suggest that the hole is equally shared by a set of three equivalent oxygen ions adjacent to a cation vacancy. The photo-induced redistribution of charge has been characterized in Bi12GeO20 and Bi12SiO20 crystals. Optical excitation at 77 K converts Fe (3+) ions to Fe(2+) ions. The source of electrons (i.e., the hole traps) may be other impurities or intrinsic defects such as vacancies or anti-site cations. The intrinsic defects such as vacancies or anti-site cations. The Fe(3+) recovery during warming correlates with thermoluminescence peaks at 145, 165, and 245 K. Our results suggest that Fe(3+) ions may play an important role in the photorefractive effect in these materials. In LiTaO3, the EPR spectrum of Ta(4+) ions have been investigated. The diffusion coefficients of deuterium in single crystals of LiTaO3 have been measured by monitoring the growth of OD (-) infrared absorption bands. (AW)