Improvement of the EDFA design for both preamplifier and booster applications

We have developed and tested a new configuration of Er-doped fibre amplifier (EDFA), which enables one to efficiently amplify high and low power level signals. The key component of the set-up is a fibre loop mirror built with a variable-ratio coupler. The splitting ratio is adjusted in such a way that low power level signals are reflected for double pass amplification and extracted thanks to an optical circulator, whereas high power level signals are directly extracted from the EDFA after one single pass in the doped fibre. This new configuration is thus a double-output EDFA with each output dedicated to a particular regime.