Reduction of Fiber Four-Wave Mixing Generated from Modulated Lights by Inserting Dispersive Elements

Abstract

Four-wave mixing (FWM) is a crucial impairment factor in optical wavelength-division-multiplexing (WDM) transmission systems over dispersion-shifted fibers. This paper presents an FWM suppression scheme that places dispersive elements (DEs) such as dispersion compensation fibers at optically repeating points in transmission lines. In a DE, the relative phase of the transmitted signal lights and the FWM light generated in the previous spans is shifted. Consequently, the FWM lights generated in each span are summed in random phases and the total FWM power at the end of the transmission lines is reduced from that in straight transmission lines with no DEs. We conduct proof-of-principle experiments to confirm the mechanism of the FWM reduction. Calculation for evaluating the FWM reduction ratio in a WDM transmission system is also presented.