Question : Can you use a singlemode connector on multimode fiber? Will it perform the same, worse, or better?
Multimode 50/125 fiber. Can you terminate with a connector designed for singlemode 9/125 fiber? What are the differences in dimensions, materials, etc.? Will it work and will it meet or exceed the spec of a multimode connector?
fiber connectors

Best answer:

Answer by Kevin
The external dimensions are the same. That’s the ’125′ part of the spec .. 125 micron outside diameter. The other number is the size of the core. The Multimode you’re using has a 50 micron core, which isn’t as common as 62.5 micron multimode. The single mode that you are mentioning also has a 125 micron external circumference and a 9 micron core.

The core of the SINGLE mode is much smaller because light travels down the core in a SINGLE ray. In multimode, the light bounces down the core in MULTIple rays.

You definitely should NOT try to connect a sinlge mode connector to a multimode cable. It is important to use the appropriate connector for the kind of fiber cable you are using. In fact, you shouldn’t even mix the two different kinds of multimode (50 & 62.5).

Putting a single mode connector on a multimode cable will effectively cut out a large majority of the siganl, as much as 20 dB, which is 90% of the signal.