LAUSR

Spatial mode-count scalability in optical fibers is of paramount importance for addressing the upcoming information-capacity crunch, reducing energy consumption per bit, and for enabling advanced quantum computing networks, but this scalability is severely limited by perturbative mode mixing. We show an alternative means of light guidance, in which light’s orbital angular momentum creates a centrifugal barrier for itself, thereby enabling low-loss transmission of light in a conventionally forbidden regime wherein the mode mixing can be naturally curtailed. This enables kilometer-length-scale transmission of a record ~50 low-loss modes with cross-talk as low as −45 decibels/kilometer and mode areas of ~800 square micrometers over a 130-nanometer telecommunications spectral window. This distinctive light-guidance regime promises to substantially increase the information content per photon for quantum or classical networks. Description Twist and confinement Optical fibers form the backbone of the modern information age, with information encoded in various properties of light: wavelength, polarization, intensity, and phase. These modes rely on total internal reflection within the fiber. To further increase capacity, propagating light in different spatial modes within the fiber is possible, but this is complicated by mode mixing, in which the information is corrupted. Using light with orbital angular momentum, Ma et al. demonstrate an optical fiber designed with a topological feature that confines the light separate from that of total internal reflection, thus avoiding the detrimental issues related to mode mixing. These results suggest a route for developing higher-capacity optical networks. —ISO A topological effect was used to confine light to optic fibers for higher information capacity.