Yb3+ sensitised Er3+ doped silica optical fibre with ultrahigh transfer efficiency and gain

Abstract
Efficient 1.54 μm emission under 1064 nm excitation of Er3+/Yb3+ codoped silica fibre is reported. The energy transfer efficiency from Yb3+ to Er3+, ∼95%, even under high inversion, is comparable to that in multicomponent glass fibres. The small signal gain of ∼45dB is measured and power amplifiers with 145 mW output power demonstrated.