ABSORPTION GRATINGS IN PHOTOREFRACTIVE CRYSTALS WITH MULTIPLE LEVELS

被引:48
作者
CUDNEY, RS [1 ]
PIERCE, RM [1 ]
BACHER, GD [1 ]
FEINBERG, J [1 ]
机构
[1] UNIV SO CALIF,DEPT ELECT ENGN,LOS ANGELES,CA 90089
关键词
D O I
10.1364/JOSAB.8.001326
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
Two coherent light beams can couple in any absorbing material owing to a light-induced modulation of the material's dielectric constant. In photorefractive crystals the coupling caused by these absorption gratings appears in addition to any electro-optic coupling, complicating the interpretation of data. However, in contrast with the electro-optic gratings formed by charge diffusion, absorption gratings do not necessarily vanish as the beam-crossing angle approaches zero if there is more than one absorbing level. We show that a plot of the coupling strength of the absorption gratings versus the beam-crossing angle is characterized by only three parameters, independent of the number of absorbing levels. We use absorption gratings with a two-level model to determine experimentally some important crystal parameters, including the relative density of donors and acceptors in a barium titanate crystal. Our values agree with those obtained from measurements of the bulk light-induced absorption of the crystal.
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页码:1326 / 1332
页数:7
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