Apparatus for determining the effect of modal noise on a communication system by flexing an optical fiber

摘要

An apparatus is provided for causing a change in the physical condition of an optical fiber in order to analyze the effects of modal noise on a communication system in which the optical fiber is used. One method for performing the physical change is to flex the fiber in a flexing station that comprises two clamps that are attached to generally opposite sides of a multiple turn loop of optical fiber that is twisted to form a figure-eight pattern. The two clamps are moved away from each other and toward each other to flex the optical fiber by twisting, compressing and expanding it. A second means for changing the condition of the optical fiber is to provide an optical attenuation block that is designed to hold opposite termini of the optical fiber at a discontinuity formed therein. Two halves of the block are configured to be movable relative to each other in response to threaded members passing through selective portions of the block. Ferrules are attached with connectors, to the opposite termini that define the discontinuity and the ferrules are each attached to one portion of the block. By moving the halves of the block relative to each other, selective misalignments can be induced in the ferrule arrangement. In particular a combination of longitudinal, lateral and angular misalignment can be achieved.