Nonlinear limitation of 10Gbit/s NRZ electrical pre-distortion system

Abstract

In this paper, we study the nonlinear limitation of 10Gbit/s NRZ electronic pre-distortion (EPD) system by simulating. We constructed an ideal EPD simulation system with all chromatic dispersion compensation in electrical domain in transmitter; the fiber link includes Erbium-doped Optical Fiber Amplifier (EDFA) and 50km single mode fiber (SMF) in each span. And a dispersion compensation fiber (DCF) compensation system as a comparing object, with the fiber link includes EDFA, 50km SMF and DCF in each span. In single channel case, we find the EPD system is more sensitive with (self-phase modulation) SPM effect than DCF compensation system; in wavelength division multiplexing (WDM) system with 100GHz channel space, the cross-phase modulation (XPM) effects in EPD system induces more penalty fluctuating than DCF system. This is due to the large power variations in the waveform after large dispersion precompensation necessary for EPD. By compensating SPM effect and chromatic dispersion simultaneous in electrical domain in transmitter ideally, we can suppress SPM effect successfully in single channel system; but for WDM system, XPM effect still induces larger penalty fluctuating than DCF system. Because we can not predict signal patterns of neighbor channel, that means we can not compensate XPM effect. So, the XPM effect is the final nonlinear limitation of 10Gbit/s NRZ EPD WDM system.