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New Member

Mixing of Multimode and Singlemode


I have an OC-3 POS connection from an ISP that I want to connect to a PA-POS-OC3SMI single mode 1310nm card. Can I connect this using 1310nm multimode fibre to connect these, with the only impact being attenuation.

Thank you,



Re: Mixing of Multimode and Singlemode

I could not make any judgement on this, but I found this article on web on the single mode/ multimode fibers.

Thought it might help you to take a decision

New Member

Re: Mixing of Multimode and Singlemode

You can launch a Single-mode source into a Multimode fiber and it will work for short distances (2-3 meters). But you can not launch a Multimode source into a single-mode fiber. You will not be able to couple enough light into the fiber. Does this help

New Member

Re: Mixing of Multimode and Singlemode

SMF and MMF have different size cores and light propagates down them very differently. There are things other than attenuation you have to look out for. Single-Mode interfaces use lasers that are tuned to particular Numerical Aperatures (NA), that send light at a particular critical angle to result in TIR (Total Internal Reflection). The MMF LED has completely different properties since light is sent in multiple modes and the fiber is "usually" graded (not step index which uses the TIR concept). Dispersion could be a problem depending on the distance you're going with the signal.

Can it be done? Absolutely. Would I rely on it? No. How good are you with an OSA and figuring out dispersion? If you'd rather not get into this, use the correct fiber.


Dennis Hartmann

Instructor -

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