When a visible laser beam passes through beta-BaB2O4 (BBO), scattered light
can be observed along the beam within the crystal. Scattering centers caus
ed by structural defects in Czochralski-grown BBO can be reduced by 95% by
annealing at 920 degrees C. In the flux-grown BBO, centers actually increas
e by the same annealing because the process causes microcracks and/or secon
dary inclusions. It is shown that annealed Czochralski-grown BBO is superio
r to flux-grown BBO (annealed or as-grown) in terms of optical loss. (C) 19
99 Optical Society of America.