Bandwidth-Decomposed Analysis of Spatial-Mode Dispersion of Coupled 2-Core Fiber Employing Linear Optical Sampling

The complex impulse responses of two types of coupled 2-core fibers, with homogeneous and heterogeneous cores, were measured by using a measurement system based on linear optical sampling. The measurements were performed over a bandwidth of 20 nm (∼2.5 THz), and the spatial-mode dispersion (SMD) was analyzed. Several lengths of both homogeneous and heterogeneous core fibers were prepared to investigate the length dependence of SMD. The SMDs for divided frequency bands were examined by numerically analyzing the measured broadband impulse response. Consequently, the power impulse response at each subband was obtained, and the variation in the SMDs was examined. In addition, the statistical distribution of the SMD was revealed to be different for each type of the 2-core fiber. The SMD observed at a specific band is handled by the receiver in space-division multiplexing transmission systems. Finally, we present a measurement of mode dependent loss (MDL) of a 2-core fiber, and discuss the impact of time axis inaccuracy to the MDL measurement. These analyses performed are expected to be beneficial for designing such systems.