Single-mode and Multi-mode Attenuation Reference Fibres
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Manufacturers require low attenuation fibre to allow transmission over longer distance and decrease the number of high cost repeaters. NPL can supply reference standards for both single-mode and multimode optical fibre, which have been characterised for total attenuation over a wide spectral range using the cut-back technique.
The artefact consists of a length (usually 13 km for single-mode fibre, 4.4 km for multi-mode fibre) wound on a standard shipping reel. The attenuation is measured using the internationally recognised reference test method; the cut-back technique. This technique compares the power transmitted through a very short length of fibre to that transmitted through the entire length of the fibre under test.
Fibre types that can be supplied include:
Matched Clad - Standard or SMF28 fibre
Dispersion shifted fibre
50/125 µm multimode fibre
62.5/125 µm multimode fibre
Other lengths of fibre and different fibre types can be provided on request.
Fibre attenuation plot - The graph above shows a typical plot of total attenuation as a function of wavelength for single mode fibre.
The optical length of the fibres can also be calibrated, and if connectors are fitted to the fibre, they can be used to calibrate OTDR's.
A copy of a typical Calibration Certificate is available to download.
Optical Characteristics
| Fibre Type | Measurement range | Attenuation (dB/km) | Typical measurement uncertainty |
| Single mode | 1200 to 1650 nm | 0.34 (@ 1310 nm) | ± 0.03 dB |
| 0.19 (@ 1550 nm) | |||
| 50/125 µm | 800 to 900 nm | ≤ 2.5 dB/km | ± 0.06 dB |
| Multimode fibre | 1250 to 1350 nm | ≤ 0.7 dB/km |