Product
OptiX OSN 6800
OptiX OSN 8800
OptiX BWS 1600G
OptiX Metro 6100

Symptom
The Raman amplifier is used for power amplification on an ultra-long haul span. The Raman
amplifier, however, is not connected to the ODF by means of fiber splicing as instructed. As a
result, the end face of the interconnected fiber is burnt and services cannot be provisioned.



Cause ***ysis:

On-site investigation shows that the Raman amplifier is connected to the ODF using an SC-SC
fiber, instead of by means of fiber splicing. This fault brings about the risks described as follows.
• As shown in the following figure, extremely high optical power may cause serious skin
burn or eye damage when people open the connector or interconnect fibers. In addition, a
high-power laser may set fire in the equipment room.


• If fibers are not spliced on the ODF, the end faces of fibers can be burnt easily, because the
pump optical power of the Raman amplifier is extremely high (a maximum of 30 dBm and
laser safety class of CLASS 4). After the end faces are burnt, the insertion loss of fibers
increases greatly, and thus services are interrupted.

The end face of SC fibers can stand a maximum optical power of 500 mW (approximately 27
dBm). The end face gets burnt easily when the glue that fixes the core in the ceramic insert core
melts under high optical power.

In addition, the movable SC-SC connector can absorb tiny particles, such as metal particles. The
carbon contents in the dust are likely to degrade optical power, causing bit errors and even service
interruptions. This fault may occur when the optical power reaches 50 mW (approximately 17
dBm). The following figure shows a burnt fiber core and the metal particles on the ferrule
end face.


Hence, a high-power laser like the Raman amplifier cannot be used with a connector
like SC and ST connectors. Metal scraps are produced after long-time use of metal-cased
connectors. Instead, the plastic-cased connectors, such as LSH/APC-LSH/APC connector (or
E2000-E2000 connector if called casually), are recommended.

Procedure

Check the end faces of the interconnected fibers with a microscope and find that the end faces
are seriously burnt. Replace the interconnected fiber jumpers, and connect the Raman amplifier
to the ODF by means of fiber splicing. Then, services can be provisioned.

Result
The problem is resolved.

Good read, we do have ultra long haul links with RAU/RPC boards installed. Thanks for sharing.

I would say, efforts are to be made to bifurcated and add an additional node to refrain from installing RAU boards, check your budget before!

Huawei should devise a permanent fix as splicing fibers at Line ODF, is making OFC maintenance hard.

Any else is facing the same issue?

chronic issue.