L-UND C- BAND OPTISCHER VERSTÄRKER

The invention concerns a C-band and L-band optical amplifier, comprising a first stage with an amplification fibre (8) common to both the C-band and the L-band, a second stage with a branch (14) for the C-band signals and a branch (12) for L-band signals with an amplification fibre (20). The invention is characterised in that the major part of the C-band power is generated in the common amplification stage. Moreover, the amplifier comprises a power splitter (24) in the branch for C-band signals splitting in the counter-propagating direction a pumping light for the first stage amplification fibre. The invention enables to simplify the structure of the amplifier and to limit the number of devices traversed by the L-band signals after they have been amplified in the first stage common amplification fibre. It improves the signal-to-noise ratio in L-band.