Modelling of high-power diode-pumped erbium 3 mu m fibre lasers

We present theoretical calculations that relate to the cw operation of a hi gh-power Er3+, Pr3+:ZBLAN double-clad fibre laser. Using the measured energ y-transfer, energy-transfer-upconversion and cross-relaxation parameters re levant to Er3+-doped and Er3+, Pr3+-codoped ZBLAN, we compare the theoretic al calculations from the model with recent experimental measurements. The m odel is then used to analyse the important pump and interionic processes oc curring in Er3+, Pr3+:ZBLAN fibre lasers. The theoretical results indicate that energy transfer from Er3+ to Pr3+ leads to a fast depletion of the low er laser level and, due to the cw threshold condition, to low population de nsities in both laser levels. Thus, ground-state bleaching, pump excited-st ate absorption and energy-transfer upconversion amongst the Er3+ ions are a voided.