Summary

Amendment 1 to Recommendation ITU-T G.650.1 (2010) is aimed to provide measurement procedures for coherent multi-path interference (MPI) in short optical fibre cables (jumpers). An improvement in bending-loss in a single-mode fibre affects not only the fundamental mode but may also influence the higher order modes. This may change the cut-off wavelength mechanism. In this case, the single-mode operability of an optical fibre can be investigated by evaluating the MPI characteristics.

Appendix IV introduces three kinds of test methods:

–           ECL/PM (External cavity laser/Power meter) method,

–           LED/OSA (Light emitting diode/Optical spectrum analyser) method,

–           FS (Fibre stretching) method.

A new note is added at the bottom of clause 3.6.1 which gives reference to MPI and the addition of Appendix IV.