@article {oh1999thermal, title = {Thermal effects on the excited state absorption and upconversion process of erbium ions in germanosilicate optical fiber}, journal = {Journal of non-crystalline solids}, volume = {259}, number = {1}, year = {1999}, pages = {51{\textendash}56}, publisher = {Elsevier}, author = {Pettit, Erin and Simpson, Jay and Oh, Kyunghwan and Morse, TF} }