However, as fiber transmission capacity continues to grow, these technologies are approaching their physical and performance limits.
Consequently, recent R&D has focused on loosely coupled multicore optical fiber with multiple independent cores within a single optical fiber. While this type of fiber significantly increases transmission capacity, intercore crosstalk, caused by interference resulting from light leakage between each core, degrades transmission quality. This varies not only due to the design and manufacturing of the optical fiber but also depending on installation conditions, necessitating the evaluation of intercore crosstalk under real-world conditions. Although several companies and research institutions have proposed different methods for measuring intercore crosstalk, the results obtained with each method have not yet been adequately validated.
In the comparative evaluation presented, Anritsu, in collaboration with Fujikura, measured crosstalk between cores using four methods: two with optical power meters and two with Anritsu's OTDR (Optical Time Domain Reflectometer) to measure optical fiber loss and reflection. The four-core, loosely coupled multicore optical fiber evaluated, manufactured by Fujikura, has a standard cladding diameter of 125 µm. The results measured with each method were all within ±1.0 dB at 1550 nm. Therefore, any of these four measurement methods can be chosen depending on the application scenario of the loosely coupled multicore optical fiber, such as R&D, manufacturing, and installation and maintenance (I&M), with a consistent correlation guaranteed regardless of the method used. Furthermore, these results will contribute to the future standardization of loosely coupled multicore optical fiber.
