Bismuth-doped heterogeneous multilayered fiber for O+E bands amplification

We proposed and demonstrated a bismuth-doped heterogeneous multi-layered fiber operating in the O+E bands by the design of host glass components. The bismuth-doped fiber was fabricated by modified chemical vapor deposition (MCVD) combined with solution-doping technique. In addition, the bismuth-doped fiber had a well waveguide structure without the trench-assisted. Meanwhile, two active bismuth centers (BACs) realized the coexistence and trade-off in a single fiber by the different layers of SiO₂-P₂O₅ and SiO₂-GeO₂. A double-pass and double-pump amplifier configuration was established to measure the amplification performance. When the length of BDF was optimized to 140 m, the maximum gain at 1360 nm and 1420 nm obtained the same values of 22.3 dB. The >10 dB gain bandwidth was ⁓160 nm (1310⁓1470 nm). This result provided a new BDF design scheme for broadband amplification in O+E bands.