Patent ID: 7508575

Claim:
A system to deliver pump power to a remote optically pumped amplifier (ROPA) in an optical fiber communication span, the span comprising a signal carrying fiber with the ROPA spliced into the signal carrying fiber at a distance from either the transmitter end for post-amplification or from the receiver end for pre-amplification, and the ROPA being pumped by optical power at a pump wavelength λ p carried by at least one pump delivery fiber, said at least one pump delivery fiber having Raman properties whereby effective transmission of power at the pump wavelength λ p is limited by a maximum launch power at λ p , the system comprising for each pump delivery fiber: a primary pump source at wavelength λ 0 , shorter than the ROPA pump wavelength λ p ; means to provide substantially lower power at two or more seed wavelengths λ s1 . . . λ sn , where n≧2 and λ 0 <λ sn ≦λ p , and where the ensemble of seed wavelengths contains at least one at the ROPA pump wavelength λ p ; coupling means to input power from the primary pump source and power at the two or more seed wavelengths into said pump delivery fiber at said transmitter end for post-amplification or at said receiver end for pre-amplification, wherein: the primary pump wavelength is less than the wavelength λ p by an amount corresponding to n Raman shifts in the delivery fiber and where the ensemble of seed wavelengths contains one in the vicinity of each intermediate wavelength λ/ , where l=n−1, n−2 . . . 1, and denotes the number of Raman shifts in the delivery fiber between the wavelength λ/ and the ROPA pump wavelength λ p , and said primary pump and said means to provide substantially lower power at two or more seed wavelengths are configured to cause said power from the primary pump source and power at two or more seed wavelengths coupled into said pump delivery fiber to provide more power at the pump wavelength λ p to the ROPA than would be provided by coupling the maximum input power level at the pump wavelength λ p into said pump delivery fiber at said transmitter or receiver end.