MLM designed for SM fiber?

If you have a MLM laser designed for use on single mode fiber, I assume some of the extra modes get transmited onto the single mode fiber.

Do these extra modes cause problems with a SLM receiver at the other end? Is it assumed the single mode fiber dissipates the extra modes over distance? What distance is needed? 2 km?

If you connect your single mode optical power meter to this MLM laser, using a SM fiber jumper, is the reading going to be accurate? Is the actual power greater than the reading?

Sorry for all the questions, but we're connecting an MLM interface to an SLM interface (IR1) over a short distance, and while the power readings are within range, it appears the SLM interface is getting overloaded, and causing line and section level SONET errors. Adding attenuation seems to clear it up.

thanks.

Reply to
jakeb221
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I suppose that you are injected light from a multimode fiber laser device into a single-mode fiber. Depending on the details of the connection, light from different modes may couple into the core of the single-mode fiber. This can lead to interference effects, which may be responsible for your problems.

Also, a lot of power can get into the cladding of the single-mode fiber. From there, it is usually lost over a short distance, and should not couple into the core, but the detailed behavior can strongly depend on the circumstances.

Yes, it may be greater, since you may well loose a significant amount of power.

Your project may profit from consultancy, as is available e.g. from my company.

Dr. R=FCdiger Paschotta RP Photonics Consulting GmbH

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Reply to
Paschotta

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