We demonstrate mode-division multiplexed WDM transmission over 50-km of few-mode fiber using the fiber’s LP₀₁ and two degenerate LP₁₁ modes. A few-mode EDFA is used to boost the power of the output signal before a few-mode coherent receiver. A 6×6 time-domain MIMO equalizer is used to recover the transmitted data. We also experimentally characterize the 50-km few-mode fiber and the few-mode EDFA.

A structured optical fiber is drawn from a 3D-printed structured preform. Preforms containing a single ring of holes around the core are fabricated using filament made from a modified butadiene polymer. More broadly, 3D printers capable of processing soft glasses, silica, and other materials are likely to come on line in the not-so-distant future. 3D printing of optical preforms signals a new milestone in optical fiber manufacture.

We report the first (to our knowledge) development of a Bi/Er/Al/P codoped germanosilica optical fiber showing ultrabroadband luminescence between 1000 and 1570 nm, covering O-, E-, S-, C-, and L-bands, when pumped by 532, 808, or 980 nm lasers. The fluorescence profiles are found highly pump wavelength dependent, closely associated with different combinations of excitations from both Bi centers and Er ions as active centers. With a proper selection of pump wavelength(s), this Bi/Er codoped fiber could be used as an ultrabroadband gain medium for ultrabroadband amplified spontaneous emission sources, fiber lasers, or amplifiers in telecommunications and in other fields.