High two-wave-mixing gain in a Bi//12 SiO//20 Crystal at v = 633nm

Strong beam coupling with the net gain of 4000 under an external alternating electric field was observed in a Bi12SiO20 crystal at λ = 633 nm with a response time twice faster than in Bi12TiO20 at the same laser beam intensitiy. Nominally pure Bi12SiO20 crystal was grown by the Czochralski method from stoichiometric melts of Bi2O3 and SiO2 at very low temperature gradients. About 37 % deficiency of silicon in grown crystal was estimated by the optical emission spectroscopy analysis. Significantly higher photorefractive efficiency of our BSO crystal in red and near infrared region of spectrum can be explained by higher concentration of stoichiometric defects due to the silicon deficiency.