This International Standards applies to circulators used in the field of fibre optics bearing all of the following features:
- they are non-reciprocal optical devices, in which each port is either an optical fibre or fibre optic connector;
- they are passive devices in accordance with the categorization and definition provided in IEC/TS 62538;
- they have three or more ports for directionally transmitting optical power.
Example of optical circulator technologies is described in Annex A.