Optical core-to-core crosstalk in rod-type multicore fibers

In this work we present a comprehensive parameter study on core-to-core power coupling in multicore fibers (MCFs). In order to do this, a simulation tool has been developed. We chose MCFs with 3x3 cores in a squared pattern with core sizes ranging between 15 and 50 µm and core-to-core distances of 1.5 to 5 times the core diameter. The central core is seeded by a perfectly matched Gaussian beam and the power evolution in each core along the fiber is calculated up to lengths of 2 m. We will show that coupling effects not only depend on the core distance and the core NA, but also on the core diameter and the wavelength. Our simulations predict that a simplified 3x3 core arrangement can be even used to quantify coupling effects in MCFs with more cores when the core-to-core power coupling is kept low. This comprehensive study is crucial for designing laser-active rod-type MCFs.