Progress on Raman amplifiers

Raman amplifiers are of interest both as discrete amplifiers at wavelengths where no attractive rare-earth-doped silica fiber amplifiers are available and as distributed amplifiers for repeaterless applications and capacity upgrades. Recent advances in high-power fiber lasers have enabled the construction of the practical pump lasers needed to pump Raman amplifiers, thereby renewing interest in this versatile technology. In this paper, we describe the technologies that have made this revival possible and review recent progress on Raman amplifiers, discrete and distributed, analog and digital, at both 1.3 and 1.5 /spl mu/m.