Suppression of modal noise of a graded-index multimode fiber in a white-light interferometric system

Abstract

A study on the effect of modal noise induced by the modal coupling effect in a graded index multimode fiber, illuminated by a light source with a tunable coherence length was carried out. It has been shown that the value of the signal-to-noise (S/N) ratio in an interferometric system could be reduced by the perturbation-induced modal noise if in the coherence length is in the region of 30 to 80 micrometers . As the coherence length increase, the S/N ratio will reduce correspondingly. However, when the value of the coherence length is in the region of 80 micrometers and upward, the value of the corresponding reduction in S/N ratio was seen to vary only over a very small range.