Photorefractive Damage Mechanisms in Electro-Optic Materials
Abstract
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1990
- Accession Number
- ADA219786
Entities
People
- Larry E. Halliburton
Organizations
- Oklahoma State University–Stillwater