The revival of Raman amplifiers

The extensive work on Raman amplifiers conducted in the mid 1980's abruptly ended with the advent of erbium doped fiber amplifiers. However, 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 in Raman fiber amplifiers, discrete and distributed, analog and digital, at both 1.3 and 1.5 /spl mu/m.