Elimination of four-wave mixing in dispersion-shifted optical fibers by using midway optical phase conjugation in a semiconductor optical amplifier

Summary form only given. In long-distance wavelength-division multiplexed (WDM) optical communication system, the cross talk generated from four-wave mixing (FWM) in optical fibers limits the performance of the system, when channel wavelengths are set near the zero-dispersion wavelength of optical fibers. To cope this problem, it was pointed out that midway optical phase conjugation could cancel such cross talk induced by FWM. In the proposed system the FWM sidebands grown by Kerr nonlinearity of the first half of the fiber link bring back their power to the original signal through Kerr nonlinearity of the latter half of the fiber link. This process is possible owing to the time reversal nature of optical phase conjugation. In this paper, we experimentally demonstrate that a midway optical phase conjugator using a semiconductor optical amplifier actually eliminates FWM sidebands from a dual-channel signal transmitted through dispersion-shifted optical fibers.