Recent Progress in Multimode Fibers

Multimode fibers (MMFs) have been a key component in short-reach transmission systems for over 50 years and remain the predominant transmission medium for Vertical Cavity Surface-Emitting Laser (VCSEL)-based short links in data centers. To meet the growing demand for higher data rates, MMFs have continuously evolved to enhance bandwidth performance. This paper provides an overview of the fundamental properties of MMFs, with an emphasis on fiber parameters that influence bandwidth capabilities. We discuss trends in increasing data rates for MMF transmission systems in data centers and review recent progress in MMF technology aimed at boosting bandwidth. In particular, we highlight innovative fiber designs, including high-bandwidth 50 μm MMFs, large-core MMFs, long-wavelength MMFs, universal fibers, MMF bundles, and multicore fibers.