Multimode fiber (MM) or singlemode fiber (SM)?

   

Often, our low volt electricians call us because they intend to fit their customers with fiber optics products (fiber optic transmitters and receivers).

It is important to know that there are two wide categories of fibers optic product :

- Equipment wich works with multimode fiber (MM),

- Equipment wich works with singlemode fiber (SM),

Don't forget to ask your customers what they use !

The next question is : what's the difference between Multimode fiber and singlemode fiber? It's simply a difference in fiber core diameter.

1- The singlemode fiber has a 9 µ core diameter,

2- The multimode fiber has a 62.5 µ or 50 µ core (this is a little more complicated).

This is not an issue when chosing the electronic products as they are compatible with both diameters, but you will need to know in the case that you need to supply patchcords to the customer.

Now, I can quickly explain what changes in the propagation of the light (your transformed signal).

In singlemode fibers (SM), the core is so small that the light travels in a straight line (I am purposefully simplifying) where in multimode the light bounces against the lining. If you would like to go into more details on the subject, take a look at our site : "a bit of theory"

As a general rule all fiber optic transmitters and receivers exists in multimode and singlemode ; it's easy enough to check this thanks to the famous datasheet or technical document. Just look for the initials SM or MM. You can check this out via the technical instructions of a product wich allows analogic video to be transporter on SM or MM fiber (take a good look at the little table at the bottom of the  third page : video via fiber optic

Does that make more sense ? I hope so !

In either case, please leave your comments

Thank you for your visit.

See you soon, take care

Ofnictcennoc

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