Macro-bending measurement based on a correlated FLRD system with an ASE source

A passive correlated fiber loop ringdown (FLRD) system based on an amplified spontaneous emission (ASE) source is proposed and experimentally demonstrated for macro-bending measurement. Due to the randomness of spontaneous emission, the autocorrelation coefficient of ASE has an extremely narrow FWHM (0.114 ns), which allows shorter fiber loop and higher sensitivity. The experimental results show that our system with a fiber length of 2.1 m can identify the bending within tens of nanoseconds. When the bending diameter remains 2.5 cm, the sensitivity of bending turns reaches 0.0017 n s − 1 / t u r n . This system provides an effective solution for fast bending fault diagnosis.