Compositional Dependence of Infrared Transmission in Ge‐Based Chalcogenide Glasses

As for an optically homogeneous glass with thickness tantamount to a few millimeters, the longer wavelength side of its optical transmission window normally takes shape as a result of multiphonon absorption. Mainly due to the complexity inherent in glass structures, a quantitative numerical assessment of the vibrational spectrum of a given glass composition is normally not a simple task. The conspicuously dissimilar infrared transmission edges between oxide and halide glasses, for example, can be understood qualitatively in terms of the Szigeti relation; however, the relatively insignificant but clearly distinguishable changes in infrared transmission edge resulting from compositional modification in a glass‐forming system are lacking a numerical assessment. Herein, it is experimentally verified that the infrared transmission edge of Ge‐based chalcogenide glasses can be correlated in a quantitative manner with their chemical composition through combining their average bond energy and molar mass. Ternary or quaternary chalcogenide glasses exceeding 100 different compositions are used to justify this numerical correlation. The infrared transmission edge of Ge‐containing chalcogenide glasses turns out to be quantitatively estimated solely based on their chemical composition via average bond energy and molar mass. This compositional dependence is also verified in the case of mixed‐chalcogen glasses. Refractive index dispersion of chalcogenide glasses in the long‐wavelength infrared range is then facilely deduced.