Optical Time Domain Reflectometry for Simultaneously Characterizing Forward and Backward Crosstalk Along Multi-Core Fibers

Abstract

Uncoupled multi-core fibers (MCFs) are promising transmission media for realizing long-haul and large-capacity transmission using space division multiplexing. When the assignment of the signal transmission directions in adjacent cores is unidirectional or bidirectional, the forward and backward crosstalk respectively limits the capacity and distance of the transmission system using uncoupled MCFs. Understanding both the forward and backward crosstalk is crucial for determining an optimal transmission scheme according to traffic demands. In this paper, we propose a novel method based on optical time domain reflectometry for simultaneously characterizing the forward and backward crosstalk along uncoupled MCFs. We measured the forward and backward crosstalk along a four-core fiber by the proposed method. The forward and backward crosstalk obtained with the proposed method agreed well with those measured with unidirectional and bidirectional transmission methods. Since the proposed method enables us to simultaneously evaluate the forward and backward crosstalk along uncoupled MCFs from one end, it would be useful for testing those characteristics during the construction of MCF transmission lines.