Advanced fibre components for high density metropolitan WDM networks

We have experimentally demonstrated superior performance of low dispersion 25 GHz and 50 GHz fibre Bragg gratings based on a new design technique. When the gratings were cascaded the usable bandwidth for in-band channel was retained within 80% and power penalty for passband channel was below 0.5 dB. We have also demonstrated advantages of Raman amplifiers in metropolitan networks. Application of distributed Raman amplification allows us to increase dynamic range of the transmitted signals by 8 dB. Furthermore node loss compensation by Raman gain results also in lower power penalties than in the case of lumped EDFA.