Anritsu Corporation, a Japanese multinational corporation manufacturing test and measurement equipment for telecommunications, in collaboration with Fujikura, a Japanese manufacturer of cables and optical fibres, has measured inter-core crosstalk in weakly-coupled multi-core optical fibres using multiple methods and has confirmed that the results are equivalent. Both companies presented their results at the international OptoElectronics and Communications Conference (OECC 2025) in Sapporo, Japan.
With the growing adoption of artificial intelligence (AI) and cloud services, the demand for higher transmission capacity in optical submarine cables and data centre interconnects is rapidly increasing. Today’s optical communications rely on single-mode fibre (SMF) and advanced signal optimisation technologies to achieve high data throughput. However, as the transmission capacity per fibre continues to grow, these technologies are approaching their physical and performance limits.
Consequently, recent R&D has focused on weakly-coupled multi-core optical fibre with multiple independent cores in a single optical fibre. While this type of fibre significantly increases transmission capacity, inter-core crosstalk – caused by interference resulting from light leakage between each core – degrades the quality of transmission. This varies not only due to the optical fibre design and manufacturing, but also depending on the installation conditions, requiring evaluation of inter-core crosstalk in field conditions. Although various companies and research institutions have proposed different methods for measuring inter-core crosstalk, the measured results from each method have not yet been adequately validated.
In the presented comparative evaluation, Anritsu, collaborating with Fujikura, measured inter-core crosstalk using four methods: two using optical power meters, and two using Anritsu’s OTDR (Optical Time Domain Reflectometer) for measuring optical fibre loss and reflection. The evaluated four-core weakly-coupled multi-core optical fibre manufactured by Fujikura features a standard cladding diameter of 125 µm. The measured results from each measurement method were all within ±1.0 dB at 1550 nm. Consequently, any of these four measurement methods can be chosen according to the weakly-coupled multi-core optical fibre application scenario, such as R&D, Manufacturing, and Installation and Maintenance (I&M), with assured consistent correlation regardless of which method is used. Furthermore, these results should assist with future standardisation of weakly-coupled multi-core optical fibre.
Anritsu says it will continue to contribute to the practical implementation of next-generation optical communications technology by providing test solutions for weakly-coupled multi-core optical fibres.
