National Physical Laboratory

Attenuation Coefficient Uniformity

Calibration of the attenuation coefficient uniformity of single-mode optical fibres at 1310 nm and 1550 nm. UKAS accredited service.

The attenuation uniformity of single-mode fibres can be measured using a calibrated and well characterised OTDR which has been adapted to measure over all polarisation states, thus removing anomalous features arising from polarisation effects.

Measurements are typically made of seqential 1 km sections within the fibre, starting between 0.5 km and 1 km from the end. Measurements are quoted for OTDR measurements made from each end of the fibre and for the average.

NPL can supply (or measure customer's) single-mode fibre for attenuation uniformity. NPL typically supplies 12 km lengths of spooled fibre calibrated for attenuation uniformity and optical length. Also available is the NPL Fibre Attenuation Standard, which has proven attenuation stability better than ± 0.03 dB.

Fibre lengths between 4 and 14 km can be accommodated. Lengths greater than 14 km can also be measured but are not UKAS accredited.

A copy of a typical Calibration Certificate is available to download.

Measurement Range Typical Uncertainties
0.17 dB/km to 0.43 dB/km ± 0.009 dB/km (each end)
± 0.006 dB/km (average of both ends)


Customer Service tel: +44 20 8943 8637

Last Updated: 18 Aug 2015
Created: 26 Jul 2007


Please note that the information will not be divulged to third parties, or used without your permission