D.F. Grosz

All-Raman ultralong-haul single-wideband DWDM transmission systems with OADM capability

In this paper, we present a comprehensive experimental investigation of an all-Raman ultrawide single-band transmission system for both 10 and 40 Gb/s line rates. Enabling technologies include forward-Raman pumping of the transmission fiber, counter-Raman pumping of the fiber spans and dispersion compensation modules, wideband dispersion, and dispersion-slope compensation, and modulation formats resistant to both linear and nonlinear impairments. Ultralong-haul (ULH) 128/spl times/10 Gb/s return-to-zero (RZ) and ultrahigh-capacity (UHC) 64/spl times/40 Gb/s carrier-suppressed (CS) RZ transmission are demonstrated for commercially deployed fiber types, including both standard single-mode fiber (SSMF) and nonzero dispersion shifted fibers (NZDSF). The span losses of 23 dB (NZDSF) and 20 dB (SSMF) are consistent with those encountered in terrestrial networks. The optical reaches for 10 Gb/s rate are 4000 km (NZDSF) and 3200 km (SSMF). Using the same distributed Raman amplification (DRA) scheme, UHC over 2.5 Tb/s at a 40-Gb/s per channel rate is also demonstrated for all of the tested fiber types and for optical reaches exceeding 1300 km. We then study the impact of including optical add/drop modules (OADMs) in the transmission system for both 10 and 40 Gb/s channel rates. System performance is characterized by the system margin and the transmission penalty. For all of the experiments shown in this paper, industrial margins and small transmission penalties consistent with operation in commercially deployable networks are demonstrated, showing the feasibility of practical implementation of all-Raman amplified systems for ULH and UHC optical backbones. Attractive features of single-wideband transmission enabled by DRA include simplicity of design, flexible gain and gain-ripple control, good noise performance, and a small system footprint.

Ultra-high-capacity long-haul 40-Gb/s WDM transmission with 0.8-b/s/Hz spectral efficiency by means of strong optical filtering

An all-Raman single-band transmission of 5.12 Tb/s (128/spl times/42.7 Gb/s) with 50-GHz channel spacing over 1280 km of standard single-mode fiber is successfully demonstrated. This ultra-high capacity for a spectral efficiency of 0.8 b/s/Hz is achieved by strong optical filtering of transmitted signals. Simulation results and an analysis of the impairment factors to system performance are also presented.

Ultralong-haul transmission of 40-Gb/s RZ-DPSK in a 10/40 G hybrid system over 2500 km of NZ-DSF

We report on dense wavelength-division-multiplexing transmission of 40-Gb/s return-to-zero differential phase-shift keying at distances of 2500 km over conventional nonzero dispersion-shifted fibers with large system margins and small transmission penalties in a hybrid system comprising of interleaved 10and 40-Gb/s data rates. We use all-Raman amplifiers with 100-km amplifier spacing and compare the transmission performance of the hybrid system to that of a system carrying only 40-Gb/s traffic.

Performance of a ULH single wide-band all-Raman DWDM transmission system over dispersion-managed spans

We evaluate the performance of an all-Raman ultralong-haul dense wavelength-division-multiplexing transmission system over 4160 km of dispersion-managed fiber. Enabling technologies include forward and backward-propagating Raman amplification and single-modulator return-to-zero transmitters. Large optical signal-to-noise ratio margins and small transmission penalties are achieved by means of a simple dispersion map.

Analytical solution of transmission performance improvement in fiber spans with forward Raman gain and its application to repeaterless systems

A simple analytical expression for the optical signal-to-noise ratio (SNR) benefit expected from adding forward Raman gain to backward Raman gain in a fiber transmission span is derived. This result is then applied to modify the stimulated Brillouin scattering (SBS) threshold for the case of a signal experiencing forward Raman gain. These concepts are applied to demonstrate repeaterless transmission of 10 and 40 Gb/s data rates over standard single mode fiber (SSMF).