In telecommunication, the term mode scrambler (mode mixer) has the following meanings:

  • A device for inducing mode coupling in an optical fiber.
  • A device composed of one or more optical fibers in which strong mode coupling occurs.

Mode scramblers are used to provide a modal distribution that is independent of the optical source, for purposes of laboratory or field measurements or tests.

Source: from Federal Standard 1037C and from MIL-STD-188