Study of Fundamental Photoelectric Properties Related to Formation of Holographic Gratings in Photorefractive Materials

摘要

This report results from a contract tasking A.F. Ioffe Physical- Technical Institute as follows: The contractor will investigate the relations between photoelectric and electric properties of several doped noncentrosymmetric crystals, mainly of iron doped lithium niobate crystals, LiNbO3:Fe, and their photorefractive properties. Photovoltaic effect, photo- and dark conductivity will be studied experimentally in parallel with studies of formation and other properties of holographic gratings in the samples of LiNbO3:Fe, which differ in the stoichiometry of the host (Li/Nb ratio), the concentrations of Fe ions, the Fe2+/Fe3+ ratios, and the concentrations of hydrogen. The experimental results and their theoretical analysis will allow the process of holographic grating formation in LiNbO3:Fe to be established on a microscopic level. The distribution of electric fields and charges in holographic gratings will be investigated spectroscopically and the microscopic structure of the Fe-centers dominant in photoelectric and photorefractive properties of LiNbO3:Fe crystals will be examined. Also, the photorefractive and photoelectric properties of strontium barium niobate, SrxBa1 xNb2O6 (SBN with x=0.61), will be studied. The proposed studies are to be conducted with the use of experimental facilities of the Solid State Optics Department of Ioffe Institute.