Numerical modeling of three-level system in ytterbium-doped photonic crystal fiber laser

In order to investigate the power characteristics of the Yb-doped photonic crystal fiber(PCF) laser, we have represented a simple three-level system modeling based on a rate equation model. According to our theoretical modeling, the variation of the output power P out via the pump power P p is theoretically studied, which agrees well with experimental data. Then, we have investigated the effects of the doped concentration of Yb ions, the length and the effective mode field area of the PCF on the output power P out of the Yb-doped PCF laser, respectively. The results show that the output power P out first increases and then decreases when the doped concentration of Yb ions N 0 increases and when the pump power P p and the length of the PCF L are constant. And the optimal doped concentration N m exponentially decreases when the length L of the PCF increases and the slope of the optimal doped concentration N m also decreases when the length L of the PCF increases. The output power P out first increases and then decreases when the length of the PCF L increases and when the pump power P p and the doped concentration N 0 are constant. And the optimal length L m of the PCF exponentially decreases when the doped concentration N 0 increases and the slope of the length of the PCF also decreases when the doped concentration N 0 increases. The output power P out linearly decreases when the effective mode field area A increases.