Abstract

Photorefractive ferroelectrics have quite strong anisotropy of photocurrent. In barium titanate the typical ratio between conductivities in a- and c- directions is 14-20:1.[1] In strontium barium niobate (SBN) this ratio is 1:3 , i.e. in this crystal the conductivity is higher along the c-axis, whereas in BaTiO₃ it is higher along the a-axis. Previous analysis of circular beam self-focusing (2D screening solitons) was not taking this factor into account. It was shown that in the steady state if the external voltage is applied, the refractive index change is not local and self-focusing cannot produce circular output beam [2]. For barium titanate the output beam is in fact strongly elliptic. In experiments with SBN , nevertheless, it can be close to circular.

© 2000 IEEE