What do the fiber terms 9/125, 50/125 and 62.5/125 refer to?

These terms refer to the diameter in microns of a fiber optic cable's core and cladding.

  • The first set of numbers - 9, 50 and 62.5 refer to the diameter of the fiber cable's core.
  • The second set of numbers - 125 refer to the diameter of the outside of the fiber cable's cladding.

The cladding is a special coating that keeps the light from escaping the glass core. 9/125 refers to a single mode fiber cable. 50/125 and 62.5/125 refer to multimode fiber cable.