Structure and nonlinear optical properties of PbO-Bi2O3-B2O3 glasses

Abstract

The third order nonlinear optical susceptibilities X (3) of PbO-Bi 2 O 3 -B 2 O 3 glasses have been measured by the third harmonic generation (THG) method The borate network structure in the present glass system has also been investigated by using Raman and 11 B MAS NMR spectroscopies. The coordination state and the bond character of Pb 2+ and Bi 3+ ions are discussed on the basis of low wavenumber Raman spectra. The largest X (3) obtained was 1.5x10 -2 esu for 70PbO.15Bi 2 O 3 .15B 2 O 3 ternary glass which is about 50 times larger than that of silica glass. Bismuth borate glasses show larger X (3) value than lead borate glasses in the whole composition range. The higher X (3) of bismuth borate glasses is mainly attributed to the smaller optical band gap (E g ) compared to that of lead borate system. The relationship between bond character of M-O(M=Pb and Bi) and nonlinearity was discussed. It was found that the modified Lines' linear relationship between X (3) and (n ω 2 +2) 3 (n ω 2 -1)E d /E 0 2 is adopted well for these heavy metal oxide glasses.