Raman amplifiers and component requirements

Since the [Raman] gain is created by the stimulated scattering of the pump photon, the gain wavelength will depend on the pump wavelength. For silica fiber, the wavelength at which gain occurs is shifted roughly 80 to 100 nm from the pump wavelength. An obvious benefit of this is that unlike an EDFA, where the gain wavelength is fixed by the emission spectrum of the erbium ion, the Raman gain can occur in almost any wavelength, limited only by the availability of pump lasers at the right wavelength.