Holographic measurements of optically induced refractive index inhomogeneities in bismuth titanate

Optically induced refractive index inhomogeneities (optical damage) in single crystal bismuth titanate (Bi
4
Ti
3
O
12
) have been observed by the method of forming holograms inside the crystal. The maximum index change induced by light at 4880 Å wavelength is approximately 10
^-5
and lasts for a few minutes at room temperature.