Thermal stress analysis and supercontinuum generation in germanate-tellurite composite fibers

The build-up of thermal stress inside germanate-tellurite composite preforms prepared by a modified built-in casting technique was quantitatively evaluated with a theoretical model. This analysis has shown that for particular combinations of tellurite glass-made core and germanate-tellurite glass-made cladding, accumulations of thermal stress in extension and in compression occur over two different temperature ranges during the cooling of the preforms toward ambient temperature. When the glass properties are appropriate, these two regimes of stress accumulation can counterbalance each other in order to achieve a moderate structural stress inside the composite preforms. The composite fibers drawn from these preforms were then pumped with a mode-locked fiber laser centered at 1.91 mu m to assess their potential for supercontinuum generation in the infrared. (C) 2016 Optical Society of America