Abstract: A method and a system are disclosed for reducing four-wave mixing (FWM) penalties in an optical transmission network. The FWM penalties are reduced by simultaneously and periodically modulating the phase of the optical signals propagating through a long fiber waveguide at a modulation frequency that causes destructive interference of the FWM products that are otherwise generated along the length of the long fiber waveguide. The method may be implemented in an optical transmitter for an optical transmission network by providing a phase modulator between the multiplexer and an optical boost amplifier so as to simultaneously modulate the phase of all the optical signals that are transmitted through the long fiber waveguide. Alternatively, a phase modulator may be disposed between each source of modulated optical signals and the multiplexer so as to separately modulate the phase of all the optical signals that are subsequently transmitted through the long fiber waveguide.

Abstract: A method for amplifying optical signals and an optical fiber amplifier for accomplishing the same. An optical fiber is coupled to a source of pump light and a signal gain level is correlated to a dispersion value of the optical fiber that corresponds to a local minimum power level of a cross-talk signal generated by four wave mixing. Optical signals are transmitted through the optical fiber while admitting sufficient pump light into the fiber from the source to attain the selected Raman gain level.