A method and apparatus for reducing nonlinear phase noise that is induced in an optical transmission system by the interaction of optical amplifier noise and Kerr effect. The apparatus includes an intensity-scaled nonlinear phase noise compensator. The phase noise compensator reduces the nonlinear phase noise by rotating a phase estimate by a scaled signal strength estimate for the optical signal or by comparing a complex estimate of the optical signal to curved regions having scaled nonlinear decision boundaries. The scale factor is derived from the number of spans in the transmission system.