Analysis of gain characteristics of bi-directionally pumped praseodymium-doped fiber amplifiers

Signal gain and noise figure in a bi-directional pumping configuration are investigated in the unsaturated and saturated region. Balanced and asymmetric bi-directional pumping configurations are effective in the unsaturated and saturated region, respectively. Especially, an asymmetric bi-directional pumping configuration with larger backward pump power than forward pump power increases the pump to signal conversion efficiency in the saturated region. An asymmetric pumping configuration is effective in constructing booster amplifiers.