1.9~2 μm gain shifted TBDFA employing different Tm-Bi concentration ratio

A gain shift in the 1.8 μm band of Tm-Bi co-doped fiber amplifier was achieved by varying both the Tm and Bi concentrations. The effect of energy transfer in this process was studied through experimental results of three samples with different Tm/Bi ratio of 2, 0.5 and 0.2. The gain at TB-1, with highest Tm/Bi ratio showed no shift, while TB-2 and TB-3, with lower Tm-Bi concentration ratio shifted to 1950 and 1960 nm, respectively.