Ultra-wideband hybrid amplifier comprising distributed Raman amplifier and erbium-doped fibre amplifier

An extremely large seamless flat-gain bandwidth of 90.5 nm (1556.0-1646.5 nm) and transparent-gain bandwidth of 108 nm (1540.0-1648.0 nm) for a 50 km transmission fibre are achieved using a novel hybrid amplifier. The amplifier comprises a low-noise distributed Raman amplifier pumped with dual wavelengths and an erbium-doped fluoride fibre amplifier.