Numerical analysis of high power ytterbium-doped segmented-cladding fiber amplifier

摘要

We analyze numerically an ytterbium-doped segmented-cladding fiber (SCF) for optical amplification. The analysiscombines a full-vector finite-element method with propagation rate equations to calculate mode-field distributions andlongitudinal power distribution. The results show that optimal parameters depend directly on the depletion position of thepump power. With a typical ytterbium-ion concentration of 4.0x10~(25)ions/m~3, an launched pump power of 5 W, and aninput signal power of 1 μW, the maximum achievable gain is around 33 dB with an optimal fiber length of 0.6 m. Thethreshold pump power is about 500 mW for input signal power below 0.3 mW and the saturation output signal power isabout the order of 300 mW at the pump power of 5 W. The results reveal that, by using appropriate pump power, a fewmeters of ytterbium-doped ultra-large-core SCF can provide much higher gain by its large core than that of aconventional ytterbium-doped fiber while maintaining the flexibility of length and dynamic range.