Single fiber Sagnac sensing system

摘要

The system includes a generally broadband, low coherence length light source that injects light into a fiber beamsplitter that is used to generate counterpropagating light beams in a Sagnac loop. The loop includes two facing fiber beamsplitters connected together at differing length inner legs, with one of the output legs of the second beamsplitter usually being connected to an optical fiber that ends with a phase modulator followed by a mirror. Environmental effects at the optical fiber impress relative phase differences between the counterpropagating light beams, which are detected from an interferometric signal that results therefrom.