GROWTH AND OPTICAL-ABSORPTION OF PHOTOREFRACTIVE BI12SIO20 CRYSTALS DOPED WITH ZN AND CD AND CO-DOPED WITH P

Single crystals of Bi12SiO20 (BSO) Zn- and Cd-doped and co-doped with P have been grown by Czochralski technique and optimum conditions for producing optically homogeneous crystals were established. The transmi ssion and reflection spectra have been measured in the range 0.38-0.85 mu m and absorption coefficients have been determined. The Zn dopants have been found to bleach the crystals and decrease the transmission shoulder, whereas Cd dopant increases the absorption and makes the sho ulder well pronounced. P-doping strongly decreases the transmission sh oulder and shifts absorption to shorter wavelengths. The absorption co efficient of BSO doped with P has been found to decrease with dopant c oncentration increase up to 3 mol% P and above it increases with P con centration in the whole studied range. Zn + P- and Cd + P-co-doping (P concentration in the crystal less than 3 mol%) decreases strongly the absorption coefficient and shifts the spectra to short wavelengths.