The purpose of this technical report is to provide guidelines for the calculation of polarization mode dispersion (PMD) in fibre optic systems to accommodate the statistical variation of PMD and differential group delay (DGD) in optical fibre cables and components.

This guideline describes methods for calculating PMD due to optical fibre cables and optical components in an optical link. Example calculations are given to illustrate the methods for calculating total optical link PMD from typical cable and optical component data. The calculations include the statistics of concatenating individual optical fibre cables drawn from a specified distribution. The calculations assume that all components have PMD equal to the maximum specified value.

NOTE The statistical specification of the distribution of the PMD of optical fibre cables is a current work item to amend IEC 60794-3, in SC86A/WG3 [2]¹. The agreements following the last ballot (86A/501/CD) are aligned with the methods given in this technical report.

The calculations described cover first order PMD only. This study of PMD continues to evolve, therefore the material in this technical report may be modified in the future. The following subject areas are currently beyond the scope of this technical report, but remain under study:

– calculation of second and higher order PMD;

– accommodation of components with polarization dependent loss (PDL) – if it is assumed that PDL is negligible in optical fibre cables;

– system impairments (power penalty) due to PMD;

– interaction with chromatic dispersion and other nonlinear effects.

Measurement of PMD is beyond the scope of this technical report. Guidelines on the measurement of PMD of optical fibre and cable are given in IEC 61941. The measurement of optical amplifier PMD will be documented in IEC 61290-11-1². The measurement of component PMD will be documented in IEC 61300-3-32³.

¹ Figures in brackets refer to the bibliography.

² To be published

³ To be published