Multimode Fiber Optics: Recent Paradigm Shifts Driving its Resurgence

Multimode fibers theoretically support the transmission of photons in a variety of spatially, vectorially and topologically complex modes known to possess interesting linear and nonlinear properties. The large number of modes can also greatly aid energy-efficient information-capacity scaling for classical communications as well as high dimensionality for quantum networks. However, it has long been presumed that fiber-propagation mixes modes, destroying any uniquely exploitable attributes they may possess. This conventional wisdom has been upended in the last decade, due to advances in signal conditioning and reception technologies, as well as from new insights gained into the topological properties of photons. Here, we describe how this recently accessible degree of freedom for encoding information in a photon has impacted applications as disparate as quantum networks, energy-efficient internet architectures, bio-imaging, and laser power scaling.