PHOTOREFRACTIVE CHARGE COMPENSATION DURING HOLOGRAPHIC RECORDING IN BI4TI3O12

During holographic recording in Bi4Ti3O12 a primary charge grating is compensated for by a slow grating. In the dark or by homogeneous illum ination afterward, the diffraction efficiency becomes larger than the maximum value measured in the writing mode. The ratio between the effi ciencies depends strongly on the writing beam's intensity and on the g rating spacing. Turning on an intense beam additionally in the reading mode temporarily erases the slow compensation grating. Electron-hole or ionic compensation combined with a two-center model for the charge transport is used to account for the observed phenomena. (C) 1998 Opti cal Society of America.