EFFECT OF COUPLING CONDITION ON VIBRATION-INDUCED NOISE IN FIBER LEADUSED IN AN OPTICAL CURRENT MEASUREMENT SYSTEM

When using a multimode fiber lead in an optical current measurement sy stem, the optical power in the guided modes is often determined by the coupling conditions at the input end of the fiber. If only the skew r ays are excited in the fiber lead-under appropriate coupling condition s-the vibration-induced noise normally experienced in the fiber lead i n such an optical current measurement system can be effectively suppre ssed, especially when a low coherence source and a long length of mult imode fiber is used. The experimental conditions for this are consider ed and discussed in this article. (C) 1996 American Institute of Physi cs.