Abstract Bismuth tellurium oxide (Bi 2 TeO 5) is a new material expected to exhibit nonlinear
properties because of its noncentrosymmetric crystal structure. A conventional crossed cw
laser beam technique has been used to write photorefractive gratings in this material.
Typical dark decay times of the gratings are 10 seconds. In addition to the usual build-up
and decay of these gratings transient effects and oscillation of the photorefractive efficiency
were also observed.