Patent ID: 7024117

Claim:
A method for adjusting tilting of a broadband optical signal transmitted via an optical transmission fiber through injecting pump signals into the optical transmission fiber, the method comprising: transmitting a plurality of transmission bands via the optical transmission fiber; measuring signal levels of each of the plurality of transmission bands; injecting at least one pump signal and at least one further pump signal into the optical transmission fiber to add or subtract energy to and from a signal using a Raman effect when at least two signal levels of the measured signal levels of at least one of the plurality of transmission bands are changed or absent from the transmitted broadband optical, the at least one pump signal having a wavelength less than a minimum wavelength of each of the plurality of transmission bands and the at least one further pump signal having a wavelength that is greater than a maximum wavelength of each of plurality of transmission bands; and selectively setting a power level for a chosen wavelength of at least one of the at least one pump signal and the at least one further pump signal such that the tilting of a transmission band, in which signal levels do not change, remains at least substantially constant at a receiving end of the optical transmission fiber.