BaO-TiO_2-B_2O_3ガラスの構造と非線形光学特性

概要

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The third order nonlinear optical susceptibilities χ^<(3)> of BaO-TiO_2-B_2O_3 glasses have been measured by the third harmonic generation (THG) method. Raman spectroscopic investigation revealed that Ti^<4+> ions mainly exist as 4-coordinated. It was found that the addition of TiO_2 to BaO-B_2O_3 glass increases the χ^<(3)> as well as the refractive index. The positive effect of the TiO_2 on the χ^<(3)> was interpreted in terms of the empty d-orbital contribution. The largest χ^<(3)> obtained is 3.0×10^<-13> esu for 35BaO・55TiO_2・10B_2O_3 glass, which is, however, only 10 times larger than that for SiO_2 glass. Such a small enhancement in χ^<(3)> is ascribed to the large fraction of 4-coordinated Ti^<4+> ions in BaO-TiO_2-B_2O_3 glasses. It is concluded that, for TiO_2-containing glasses, the higher χ^<(3)> values are attained when the optical basicity is low and the amount of Ti^<4+> ion is large. It was found that the modified Lines' relationship between χ^<(3)> and (n_ω^2+2)^3・(n_ω^2-1)・E_d/E_0^2 is adopted for this system.
1997-04-01