Specialty Optical Fibers Handbook

As in the case of OSNR, we may distinguish two cases of dispersion limitation:

one applicable to low-cost systems, in which it is desirable to avoid in-line

dispersion compensation altogether, and the other relevant to long-reach systems

based on concatenated amplified spans.

The simplest ISI limit occurs for uncompensated transmission, in which the

dispersion tolerance of a ‘‘receiver’’—often defined as that dispersion in ps/nm

resulting in a 1-dB power penalty—limits the reach of link. For SSMF, with a

1550-nm dispersion of approximately 17 ps/nm-km, that limit is usually reached

at 60–80 km. At the time of this writing, efforts are underway to write standards

for electronically equalized receivers [2] that extend uncompensated reach with

G.652