Patent ID: 7133193
Filing Date: 2006-11-07
Classification: H01S,H04B

Abstract:
1. An optical system comprising: at least two optical nodes configured to transmit and receive optical signals between said nodes via a transmission media configured to support Raman amplification of the optical signals, wherein said transmission media includes transmission fiber having a plurality of first and second fiber sections, wherein the first fiber section has a first core diameter, and the second fiber section has a second core diameter that is less than the first core diameter; a plurality of optical amplifiers disposed between said at least two optical nodes, wherein at least one of the plurality of optical amplifier is disposed between one of the first and second fiber sections and configured to propagate optical energy in a first pump wavelength range in at least one of the first and second fiber sections to produce Raman amplification of the optical signals passing through the at least one of the fiber sections; said at least one optical amplifier includes a counter-pump source configured to counter-propagate optical energy in the transmission media in the first pump wavelength range to produce Raman amplification of the optical signals, wherein the Raman amplification has a corresponding noise figure profile over an optical signal wavelength range; said system includes a co-pump source configured to co-propagate optical energy with the optical signals in a second pump wavelength range to vary the noise figure profile of the Raman amplification produced by said counter-propagating optical energy over at least a portion of the optical signal wavelength range; at least a first one of said optical nodes is configured to launch optical signals into said transmission media at a power below a nonlinear interaction limit of said transmission media; and, said system includes at least one pump source positioned to co-propagate optical energy with the optical signals from said first optical node in said transmission media to amplify the signal channels and achieve a maximum signal channel power below the nonlinear interaction limit at a point in the transmission media downstream from said first optical node.