Fiber-optic distributed measurement of polarization beat length using slope-assisted Brillouin optical correlation-domain reflectometry

We demonstrate distributed measurement of the polarization beat length along single-mode optical fibers (SMFs) using slope-assisted Brillouin optical correlation-domain reflectometry (BOCDR) with high spatial resolution, long measurement range, high sampling rate, and single-end accessibility. The beat lengths of SMFs wound on mandrels with radii of 10.5, 7.5, and 3.4 cm are measured to be 36.0, 18.2, and 3.7 m, respectively, which agree well with theoretical calculations. This indicates that a unique beyond-nominal-resolution effect of slope-assisted BOCDR does not influence the measurement. Subsequently, distributed beat length measurement is demonstrated using an SMF comprising two sections wound on mandrels with different radii (10.5 and 3.4 cm).