Abstract

From Figure 1, it can be seen that fiber chromatic dispersion severely restricts the achievable unregenerated span lengths in high-speed lightwave systems that are constrained to use conventional (1.3-μm dispersion zero) fiber. Since most of the world’s embedded long-haul fiber has "conventional" dispersion, dispersion compensation techniques in general and dispersion compensation techniques using mid-span spectral inversion (MSSI) [1-5] in particular have received considerable attention over the past year. In the MSSI method, phase-conjugation of the signal near the middle of a fiber link allows dispersion in the second half to compensate dispersion in the first half. Recent MSSI results are plotted in Figure 1 for systems using chirped sources (open triangles) and for systems using unchirped sources (solid triangles). The results of the work described here are plotted using a square. It can be seen that the unregenerated span lengths achieved by MSSI are considerably beyond the dispersion limits shown for chirped (dashed line) and unchirped (solid lines) systems. Previous system demonstrations of MSSI were not practical for multi-wavelength-channel systems because the method used for phase conjugation was highly polarization dependent. A polarization-diversity technique [6] and a polarization-independent technique [7] for phase conjugation have been previously described. Here we use the latter in a two- channel, 10-Gb/s system demonstration.

© 1994 Optical Society of America