Abstract
Several recent experiments demonstrated the feasibility of high-bit-rate, long-haul optical telecommunications using IMDD nonreturn-to-zero (NRZ) signals in periodically amplified fiber links operating close to the zero group-velocity-dispersion (GVD) wavelength [1,2]. Both experiments [1, 2] and numerical simulations [3] show that distortion of the NRZ signal results from spectral broadening due to amplifier noise induced-four-wave mixing (FWM), and from fiber self-phase modulation (SPM) in combination with the small residual GVD. While noise-seeded FWM may be suppressed by means of dispersion management [4], the signal distortion due to SPM and GVD sets a stringent upper limit to the transmitted signal power.