Twin-core fibre erbium-doped channel equalizer

A passive channel equalizer using a twin-core EDFA is studied in detail. It relies on the spatial separation of the different channels provided by the twin-core geometry and the power-dependent differential gain saturation given by the erbium ions. The amount of channel equalization depends on the fiber geometry parameters, as well as the optical parameters and relative channel power. In the two-channel case, gain saturation limits the useful channel input powers into the range of ~ -20 dBm to -0 dBm. Channel equalization rates in excess of -0.4 dB per dB of input-power imbalance are predicted. When used in cascade, twin-core EDFAs are shown to provide not only efficient channel-power stabilization, but also self-healing against additional channel losses