Detection of discontinuities in a multimode optical fiber

摘要

A system and technique for determining discontinuities over a span of a multimode optical fiber (MMF). An optical time domain reflectometer (OTDR) has an operating port, and a first end face of a singlemode optical fiber (SMF) is coupled to the operating port. Light pulses produced by the OTDR emerge from a second end face of the SMF, and an alignment stage aligns the second end face with an end face of a multimode optical fiber (MMF) having a core of given radius. The light pulses from the second end face of the SMF are applied at selected radial positions on the MMF core to excite corresponding mode groups in the MMF. Backscatter light produced by each excited mode group is coupled to the OTDR through the SMF. Locations and values of events detected along the MMF are indicated on the OTDR for each selected radial position.