Can coherence length be a parameter to study the characteristics of optical fiber?

Question

The coherence length must be altered when passing through the fiber.So we must be able to determine certain characteristics like pulse dispersion or intensity variation using coherence length as one of the parameter.

Answer 1

I've usually heard about coherence length as being a characteristic of a laser. In particular it is an issue with cheaper laser like laser diodes.

The typical assumption is that the fiber is perfect and the the max leg length difference in a two leg fiber interferometer is given by the coherence length of the laser. But I suppose you could assume that the laser is perfect and that the coherece problems come from the fiber. Although I think that something like dispersion in the glass is likely to be identical in both legs & thus not a problem.

Sorry I couldn't be of more help.

Answer 2

A single mode fiber is required to maintain mode uniformity. A multimode fiber creates many modes that interfere with each other to form a speckle pattern. Each speckle is incoherent relative to the others. The size of each speckle could be considered a transverse coherence length, but I've not heard it described as such.