Simultaneous amplification and channel equalization using Raman amplifier for 30 channels in 1.3-μm band

A new technique is proposed to simultaneously amplify signals and equalize power unbalance caused by Raman-induced crosstalk among optical channels in the 1.3-mum band. The crosstalk is induced in GeO2-doped silica fibers due to the Raman-gain coefficient with a positive slope below the peak-frequency shift of 440 cm(-1). Highly doped GeO2 silica fiber, however, shows a negative slope across the band between 440 cm(-1) and 490 cm(-1). We propose expansion of the Raman-gain band with a negative slope over the bandwidth of 150 cm(-1) using multiple pumps. Utilizing the negative gain slope of the proposed band, simultaneous amplification and power equalization was theoretically demonstrated for 30 channels in the 1.310-1.345 mum region without external filters.