New energy-transfer upconversion process in Er3+ :ZBLAN mid-infrared fiber lasers

We report a new energy-transfer process in erbium doped ZBLAN glass, which is critical for optimizing the operation of lasers that use the 3.5 mu m band F-4(9/2) to I-4(9/2) transition. The magnitude of this energy-transfer process is measured for two different doping levels in Er3+:ZBLAN and the requirement for low doping in these lasers established. (C) 2016 Optical Society of America