TIA/TR-1028:2004

This part of IEC 61282 is a guideline providing methods of
representing the process statistics of the chromatic dispersion of
optical fibres and related components that may be combined in a
link.

Chromatic dispersion (ps/nm) is the derivative, with respect to
wavelength, of the group delay (ps) induced by the spectral content
of light propagating through an optical element or fibre. Chromatic
dispersion is normally a function of wavelength and can be either
positive (group delay increasing with wavelength) or negative
(group delay decreasing with wavelength).

The presence of chromatic dispersion can induce distortions in
signals leading to bit errors depending on

– source spectral width;

– source chirp;

– bit period;

– distance.

In addition, chromatic dispersion is interactive with the
effects of non-linear optical effects and second order polarisation
mode dispersion (PMD). The above system impairments are beyond the
scope of this technical report.

When different components or fibres are combined, the chromatic
dispersion of the combination is the total of the chromatic
dispersion values of the individuals, on a wavelength-
by-wavelength basis. A section with high chromatic dispersion will
be balanced by sections with lower values. The variation in the
total dispersion of links will therefore be dependent on the
distributions of the products that are used in the link. This
document provides methods to calculate the distribution statistics
of concatenated links based on information on the distributions of
different fibre or component populations.

NOTE In the clauses that follow, examples are given for
particular fibre and component types. These examples are not
necessarily broadly representative.