IEC 61755-2-1:2022 defines a set of prescribed conditions for a single-mode fibre optic connection that is maintained in order to satisfy the requirements of attenuation and return loss (RL) performance in a randomly mated pair of non-angled polished physically contacting (PC) fibres. The model uses a Gaussian distribution of light intensity over the specified mode field diameter (MFD) for determination of attenuation performance grades, based on MFD mismatch and the amount of lateral and angular fibre core offsets. Attenuation and RL performance grades are defined in IEC 61755-1. This second edition cancels and replaces the first edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

1. addition of normative references and visual requirement tables;
2. reconsideration of the whole parts of the text to avoid misuse of the standard.