Figure 5

For the 4.1 μm resonantly pumped Pr³⁺-doped chalcogenide fibre amplifier: (a) the output signal spectrum of the ~5.5 μm OPO laser when the pump power was at 0 and 120 mW, respectively, and (b) the total output signal intensity when the pump power was varied from 0 to 120 mW.