Fanning Laser Light Application to the Characterization of Bi12TiO20 and Bi12SiO20 Crystals

Bi12SiO20 and Bi12TiO20 photorefractive crystals were grown using the melting technique, and characterised by DTA, XRD, and chemical etching. The fanning effect is known as a self-scattering process in which a single laser light beam self-generates scattering in an asymmetrical way. The intensity distribution of fanning light in the far field measured under an applied electric field, normalised to the intensity measured without a field represents the two-wave mixing gain factor gamma. For the experiments, an argon laser with lambda = 515 nm and maximum power of 0.5 W was used and the scattered intensity was recorded. The factor gamma(theta, phi) for a set of samples was calculated using the intensity distribution in the far field, recorded with a CCD camera. The values of gamma(theta, phi) were correlated with the optical inhomogeneity of the crystals. 6 refs.