Nonlinear optical properties of TeO2-based glasses: Li(Na and K)2O–TeO2 binary glasses

The third-order nonlinear optical susceptibilities, χ(3), of the xLi(Na and K)2O · (100 − x)TeO2 binary glasses have been measured by the third harmonic generation (THG) method. It is found that the χ(3) of each series of glasses decreases with increasing alkali oxide content. The largest χ(3) values obtained are about 1.3 × 10−12 esu for a 7.5Li2O · 92.5TeO2 glass, being about 45 times larger than that of fused silica glass for the present series samples. For the purpose of investigating the relationship between the χ(3) and the optical parameters, such as linear refractive index, polarizability per unit volume which is represented by the term (nω2 – 1)/(nω2 + 2), dispersion energy (Ed) which is related to the Abbé number, and excitation energy (E0) which is closely related to the optical band gap (Eg), we derived the equations that relate the χ(3) to optical parameters on the basis of Lines’ model. Finally, it was experimentally confirmed that the χ(3) value of alkali oxide-TeO2 glasses is proportional to the term (nω2 + 2)3 (nω2 – 1) · Ed/E02