Optical reference connectors are manufactured with restricted tolerances
and are used for attenuation measurement purposes; these shall be considered
as part of the measurement set-up since they strongly contribute
to its measurement uncertainty.
In order to limit the variability of attenuation measurement using reference
connectors, Diamond uses selected single mode fiber with restricted
tolerances on (MFD) as specified within the IEC 61755-2-4 / -2-5 standard.
Using only this type of fiber and the tolerance parameters published in the
standards mentioned below, it is possible to reach measurement values
that are repeatable within ± 0.1 dB when randomly varying the reference
connector. The main parameters influencing the performance of the reference
connectors are fiber core location, fiber core axis angle and mode
field diameter (MFD) variability. Diamond manufactures high performance
reference connectors using the standardized composite ferrule, as well as
"Active Core Alignment" (ACA) technology, which allows for the minimization
of the fiber core eccentricity and the control of the angular misalignment.