Very large area single-mode multi-core fiber

Starting from a standard single-mode fiber with an effective mode area (A eff ) in the order of 30 µm2, the most obvious way to increase the power-handling capability is to increase the core diameter - and therefore the effective mode area - since the threshold of most nonlinear effects [1] is proportional to A eff . This approach led to the so-called large-mode area (LMA) fibers with an A eff of about 150 – 220 µm2. To preserve the single-mode guiding property, the numerical aperture (NA) of these fibers has to be low, typically between 0.05 and 0.07. Besides the difficulties of the production of very low NA fibers, further increasing the core diameter will result in an excessive bending sensitivity [2].