Spectral Fibre Attenuation Standard
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NPL’s specially designed and manufactured Fibre Attenuation Standard provides a high level of attenuation stability that allows accuracies achieved in national standards laboratories to be be transferred to the industrial user. The Fibre Attenuation Standard is much less sensitive to extrinsic factors such as temperature cycling and vibration and can help provide a solution to the calibration of OTDR’s and spectral scan benches. It can also be calibrated for optical length and chromatic dispersion.
Accurate measurements require traceability to national standards laboratories. This traceability is provided by a calibrated transfer standard and until recently the usual choice has been an optical fibre wound on a shipping spool. However, the measured attenuation of a spooled fibre can be highly sensitive to extrinsic factors such as temperature cycling and vibration. The NPL Fibre Attenuation Standard has been demonstrated to be insensitive to these factors.
NPL can manufacture and calibrate an attenuation standard which can be readily transported worldwide and which has an attenuation stability to within ± 0.03 dB.
Environmental tests used for the design approval of the standard included:
Dry heat for 21 days at 70 °C
Damp heat for 21 days at 40 °C and 93% relative humidity
Cold storage for 10 days at - 40 °C
Temperature cycling for five days between - 10 °C and 70 °C
Shipping tests, including transatlantic crossing with minimal packaging
Vibration testing
Versatile configuration enables many uses
Calibration of OTDR loss scale
Evaluation of fibre attenuation coefficient uniformity
Can also be calibrated for optical length and chromatic dispersion
When combined with NPL's OTDR distance scale and return loss calibration artefacts, can provide a complete solution for OTDR calibration.
Calibration of the attenuation of spectral scan benches
Specifications
Proven attenuation stability to within ± 0.03 dB
Total loss calibration accuracy typically better than ± 0.03 dB
Length ranges 2 km to 15 km
Choice of connectorised or bare fibre ends
Single-mode and multimode fibre versions available
| Fibre Type | Measurement Range | Typical Measurement Uncertainty |
| Single-mode | ~2 200 m | ± 0.1 m |
| Multimode |
~1 000 m |
± 0.3 m |