Simplex Fiber is a single fiber available in single mode, multimode, or Polarization maintaining.

Duplex fibers consist of two fibers, either single Mode or multimode, and are used in applications where Data needs to be transferred bi-directionally. One fiber transmits data one direction; the other fiber transmits data in the opposite direction.

There are two types of Duplex fibers:

• Half-duplex: Data may only be transmitted in one direction at a time.
• Full-duplex: Data is transferred in two directions simultaneously.

This should help explain the difference between Simplex VS Duplex. IF you have any further questions, feel free to visit the:

Fiber Optic Glossary.