OPTICAL-PHASE CONJUGATION OF MULTIWAVELENGTH SIGNALS IN A DISPERSION-SHIFTED FIBER

Optical phase conjugation (OPC) of multiwavelength signals in a disper sion-shifted fiber (DSF), which can be used for dispersion compensatio n in the wavelength division multiplexing communication system, is the oretically studied, The multiwavelength phase-conjugate signals are ge nerated by four-wave mixing (FWM) in the dispersion-shifted fiber, The re are the pulse-shape distortion and the induced frequency chirping i n the phase conjugate signals owing to pump depletion and the cross-ph ase modulation among the signals and phase-conjugate signals, respecti vely. The FWM among the pump wave, signals, and phase-conjugate signal s causes unequal conversion efficiencies for the multiwavelength signa ls and enhances the induced frequency chirping in the phase-conjugate signals, The induced frequency chirping may deteriorate the restoratio n of the pulse shape, Both the pulse-shape distortion and induced freq uency chirping increase with the signal and pump powers. The formula f or the induced frequency chirping that is only caused by the signals t hrough cross-phase modulation is derived, The requirement of the signa l power in the dispersion-shifted fiber for the restoration of the pul se shape by the optical phase conjugation is estimated and numerically verified.