Third order nonlinear and optical limiting properties of alkaline bismuth borate glasses

Transparent Alkaline Bismuth Borate glasses (10RO-35Bi2O3-55B2O3, where R = Ba, Ca & Sr) were prepared by melt-quenching method. The optical band gap values of the glasses are obtained from absorption spectra and found to increase due to the presence of alkaline earth ion in the order of Ba < Sr < Ca whereas optical basicity values follows the reverse trend. Nonlinear optical properties and optical limiting properties of the glasses were investigated at wavelengths of 532 and 800 nm for ns and ps and fs time domains respectively by Z-scan technique. Two-photon absorption is regarded as the dominant mechanism in the case of Sr and Ca based glasses whereas glass with Ba exhibit two photon induced three photon mechanism. Optical limiting characteristics are also reported in fs and ns regimes for these glasses.