Characterizing the differential mode group delay and modal dispersion of long few-mode fiber based on electrical spectral interferometry

We experimentally demonstrate a fast, simple, and accurate method based on the electrical spectral interferometry for measuring the differential mode group delay (DMGD) and chromatic dispersion (CD) between the higher order modes and the fundamental mode in a 5-km few-mode fiber (FMF). The interferogram information of multiple modes of the measured FMF is recorded and used to deduce the relative delay by applying the FFT processing with a simple mathematical algorithm. Based on the acquired relative delay of different fiber modes, the DMGD and CD can be obtained about (2.27 to 2.36) ps/m, (1.4 to 2.3) ps/nm. km for LP11 mode and (4.56 to 4.68) ps/m, (-1.1 to 1) ps/nm. km for LP21 mode, respectively, for this tested FMF. At the same time, a precision of +/- 0.0015 ps/m for DMGD measurement has been achieved. The experimental results show that the demonstrated method could be a good solution to the characterization of FMF used in large capacity SDM transmission systems. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)