ITU-T Recommendations

Recommendation ITU-T G.650.1 contains definitions of the linear, deterministic parameters of single-mode optical fibres and cables. It also contains both, reference test methods and alternative test methods for characterizing these parameters.

These test methods are suitable mainly for factory measurements of the linear, deterministic attributes of single-mode fibres and cables. Some of the test methods may also be used to characterize discrete optical components.

History of this Recommendation is as following:

1993 Definitions and test methods were removed from single‑mode fibre Recommendations such as Recommendation ITU-T G.652 and used to create the initial version of Recommendation ITU‑T G.650.

1997 The second version of Recommendation ITU-T G.650 added definitions and test methods for polarization mode dispersion and Appendices I, II and III. The improved determination of cut-off wavelength (clause 5.3.1.3.4) was also added.

2000 The third version established reference and alternative test methods for polarization mode dispersion, modified the definitions and test methods for core concentricity error (clauses 3.4 and 5.2), and added clause 5.1.4 and Appendices IV, V and VI.

2002 In order to facilitate maintenance, Recommendation ITU-T G.650 was divided into smaller Recommendations. Recommendation ITU-T G.650.2 contains definitions and test methods for statistical and non-linear attributes of single-mode fibre and cable.

2004 The second version of Recommendation ITU-T G.650.1 added a third alternative test method "Spectral attenuation modelling" (clause 5.4.4) and new Appendix III "Example of a matrix model". This material has been moved from the single-mode fibre Recommendations into this Recommendation G.650.1. In addition, chromatic dispersion fitting procedures have been added (Annex A).

2010 The third version of Recommendation ITU-T G.650.1 added the test method "Test methods for the macrobend loss" (clause 5.6). Jumper cut-off wavelength has been deleted from clause 5.3. Additional description has been added in cut-off wavelength test method (clause 5.3.1.3.2). Corrected Equation 5-1. Detailed description has been added in proof test method (clause 5.7). Appendix II has been updated.

2018 The fourth version of Recommendation ITU-T G.650.1 added the Appendix IV (from Amendment 1 published in 2012) to provide measurement procedures for coherent multi-path interference (MPI). The interferometric technique for chromatic dispersion measurement has been deleted from Clause 6.5 and moved to Appendix V. The description of measurement details for G.657 fibre on MFD, cut-off wavelength and spectral attenuation tests has been improved. The RTM and ATM of cable cut-off wavelength measurement has been modified. An example of interpolation method has been added in Clause I.3. Equation 6-1 has been corrected.