Equilibrium length

Equilibrium length: For a specific excitation condition, the length of multimode optical fiber necessary to attain equilibrium mode distribution.

Note: Equilibrium length is sometimes used to refer to the longest such length, as would result from a worst-case, but undefined, excitation. Synonyms equilibrium coupling length, equilibrium mode distribution length.

Source: from Federal Standard 1037C and from MIL-STD-188