Third-order optical nonlinearity in Ge-Se-Te chalcogenide glasses.

We have prepared Ge x Se 10 Te 90-x glasses with a composition of x from 17.5 to 26.25 and measured their properties using various diagnosis tools. It was found that, all the glasses have a transmittance more than 40% at a wavelength range from 2 to 15 μm, and linear refractive index n 0 decreases but optical bandgap energy E g increases with decreasing Te contents in the glasses. We also analysed the evolution of n 2 and β as a function of Ge content, both the evolution of n 2 and β are close to the prediction by Sheik-Bahae et al. for optical nonlinearity of semiconductors. In all cases, the nonlinear optical refractive index n 2 measured at 3.0 μm is larger than that at 2.5 μm due to the two-photon resonance effect, and a maximum nonlinear index is 2.46 × 10−13 cm2/W at composition of Ge 17.5 Se 10 Te 72.5. Such larger nonlinearity around 10−13 cm2/W observed in the present paper is one order of the magnitude larger than that in S- and Se-based chalcogenide glasses, demonstrating potentials of Te-based glasses for the applications as mid- and far-infrared nonlinear optical devices. • Glasses show a good transmittance more than 40% from 2 to 15 um. • n 0 decreases but E g increases with increasing Ge (and thus decreasing Te) contents. • A maximum nonlinear index is 2.46 × 10−13 cm2/W at composition of Ge 17.5 Se 10 Te 72.5. [ABSTRACT FROM AUTHOR]