Few mode Er3+-doped fiber with microstructured core enabling spectral and modal gain equalization for spatial division multiplexing

Simulations and experimental results on Er³⁺-doped fibers that amplify 6 modes over the C-band are reported. It is shown that complex Er³⁺-doping profile can hardly be achieved by MCVD process and that microstructuring the core could be an alternative to tailor the Er³⁺ doping profile. As a proof of concept, such a fiber is modeled and realized.