Modal content analysis of optical fiber based on cross-correlated and off-axis digital holography

Abstract

A fiber mode analysis method based on cross-correlation in the time domain and off-axis digital holography is presented to measure different modal contents of multimode optical fiber. A measurement system with self-developed software and hardware is established, which can measure the group-delay difference, mode energy weights, mode intensity and phase distribution of fiber under test. The group-delay temporal resolution of system reaches up to 0.27 ps at a wavelength of 850 nm and a fiber length of 2.4 m. A few-mode fiber is measured at different wavelengths and bending diameters. The modal content varies at different wavelengths, and the energy proportion varies at different bending diameters.