Novel reactive molten core fabrication employing in-situ metal oxidation: Erbium-doped intrinsically low Brillouin scattering optical fiber

Reported here is an erbium-doped, few-mode, intrinsically low Brillouin gain optical fiber fabricated using a novel reactive molten core (rMC) process involving in-situ metal oxidation. Specifically, a silica-glass clad, aluminum-metal foil wrapped crystalline Er:YAG (Y₃Al₅O₁₂) rod was drawn (during which the aluminum metal oxidizes) into an erbium-doped yttrium aluminosilicate glass core fiber. The sesquioxide dopants in the core promote an intrinsically low Brillouin gain coefficient, deduced via additivity modeling and direct measurement to be 0.19 × 10⁻¹¹ m/W. Fiber losses of 0.25 dB/m (1310 nm) were obtained as was a slope efficiency of 38.2%. The rMC process offers a straight-forward route to expand the potential precursor palette from which specialty optical fibers can be realized.