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.