Maintaining broadband gain in a Nd/Ybco-doped silica fiber amplifier via dual-laser pumping.

We report a 30 cm long Nd/Yb co-doped silica glass fiber amplifier with well-maintained broadband gain through simultaneous dual-laser pumping at 808 and 975 nm. By controlling the ratio of the pump power at 975 (P) and 808 nm (P), the emission band of Yb/Nd and the energy transfer efficiency of Nd→Yb can be well controlled; thus, a tunable broadband and flat gain in the range of 1036-1080 nm are obtained. The theoretical calculation of the energy transfer efficiency of Nd→Yb with dual-laser pumping of 808 and 975 nm explains well the mechanism of broadband and flat gain formation in the Nd/Yb co-doped fiber.