We report the design, fabrication and characterization of a few-mode ring-core fiber supporting 4 mode groups (i.e. 7 spatial modes including spatial degeneracies). By carefully designing the ring-core parameters, the fiber can support only single-radial-order modes, which enables weak intermodal coupling between higher-order modes and has potential to reduce the complexity of mode-division multiplexed digital signal processing. The low loss (~ 0.3dB/km) and long length (25.3km) RCF is successfully fabricated and they are both records for a ring-core fiber.
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