What is fiber optic Polarity?

Generally, optical flow requires 2 fibers to complete the whole transmission process. For example, there is receiving port Rx and transmitting port Rx in an optical module, the 2 ports are required to connected during working, and this connection is known as fiber optic polarity.

MPO Patch Cable

Why is fiber polarity important?

For common SC and LC duplex connectors, as there are only 2 fibers, and matching is either straight A-A B-B or crossed A-B B-A, things are easy. However, for MPO/MTP cabling system, the network is much more complicated because each MPO connector contains 12/24 or even 32 fibers inside, which makes MPO polarity important.

3 types Polarity for MPO

1. Type A – Straight

In polarity Type A, the MPO connector mating is Key up-Key down, fiber positions are the same at each side as 1-1, 2-2, 3-3….12-12.

2. Type B – Crossed

In polarity Type B, mating is Key up-Key up, the fiber positions of both side MPO connectors are reversed, the connection is 1-12, 2-11, 3-10….12-1.

3. Type C – Cross Pairs

In polarity Type C, the MPO connector mating is Key up-Key down, fiber matches 1-2, 2-1, 3-4 4-3, ….12-11.

 MPO Polarity Tester

How do you test polarity?

FSG uses a professional machine to test all types polarity, all we need to do is choose the tested polarity type and connected MPO cables. To ensure correct polarity, FSG tests polarity twice for all MPO cables during production, the first time is after the polishing process, and the 2nd time is after the assembly process. Polarity is 100% guaranteed.
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