Abstract
Photon avalanche has been achieved in an Er3+:ZBLAN fibre at room temperature, in which periodic spatial domains in the centimetre, millimetre, and 100 µm ranges have been observed. Avalanche upconversion emission has been observed at several wavelengths of which the strongest is at 550 nm. The measured threshold for the avalanche is ~ 5 mW of incident pump power at 579nm. Rise time, transmission and emissions allow mechanisms for the observed avalanche process to be proposed.