C-band and L-band optical amplifier for submarine transmission systems

The present invention relates to fiber optic transmission and more particularly to C-band and L-band amplifiers used for submarine transmission systems. The invention proposes an optical amplifier for the C and L bands having a first stage with an amplification fiber () common to the C and L bands, a second stage with a branch () for C-band signals and a branch () for L-band signals with an amplification fiber (). According to the invention, most of the power in the C band is created in the common amplification stage. The amplifier has a coupler () in the branch for C-band signals coupling pumping light for the amplification fiber of the first stage in the contrapropagating direction.The invention simplifies the structure of the amplifier and limits the number of devices through which L-band signals pass after they are amplified in the common amplification fiber of the first stage. It improves the L-band signal/noise ratio.