Non-linear optical properties of Bi2O3-TeO2-B2O3-GeO2 glasses.

New bismuth tellurite boro-germanate glasses according to composition xBi2O3-(80-x)TeO2-10B2O3-10GeO2 where (x=40, 45, 50, 55, 60 and 65 mol%) have been prepared by melt quench technique at 1150 ◦C. The room temperature optical absorption spectra have been recorded. The indirect band gap energy Eg was determined and found to decrease with Bi2O3 content. The increase in Urbach energy with glass composition indicates the decrease in structural stability. The ionic and covalent bonding parameters were determined. The present glasses are found to be 99 % ionic in nature. The two-photon absorption coefficient was found to increase from 11.89 to 14 cm/GW. The non-linear optical properties such as non-linear refractive index, linear optical susceptibility and third order non-linear optical susceptibility were evaluated using optical data. The authors determined theoretically the optical band gap (Eg) and refractive index (n) of the present glasses using optical electronegativity data. The relationship between Eg and n followed the relation Eg n4 = 99. The present glasses were found suitable for drawing optical fibers. [ABSTRACT FROM AUTHOR]