脉冲形状对脉冲经光纤放大器传输后功率增益的影响

Effect of the Pulse Shape on the Power Gain for Pulses Propagating in a Fiber Amplifier

基于描述脉冲放大过程的时间相关非线性辐射迁移方程,对不同形状脉冲经掺镱光纤放大器传输后的功率特性进行了分析,该方程同时考虑了光与介质的相互作用.数值结果表明,在相同的脉冲能量下,不同形状脉冲经放大器放大后的功率增益随入射脉冲形状不同而不同,并且功率增益的差异在脉冲前沿比较大.这使得放大器输出脉冲峰值向前沿的偏移量以及峰值功率的放大倍数都与脉冲形状有关.尤其是当入射脉冲的能量较大时,不同形状脉冲的峰值功率的放大倍数明显不同,以超高斯脉冲为最大,高斯脉冲、双曲正割脉冲次之,洛伦兹脉冲最小.

Based on the nonlinear,time-dependent radiation transfer equations,which describe the amplification process of a pulse and account for the effect of the radiation on the medium and vice versa,the power characteristics of the output pulses of a Yb-doped fiber amplifier are investigated under different input pulse shapes.Numerical results show that,the power gain of the pulse traversing the amplifier is different for different shapes when the average energy of the input pulse is the same.This difference is larger in the leading part of the pulse,which leads both the gain value and the shift value of the peak power for the output pulses to be dependent on the input pulse shape.Especially,when the input pulse energy is relatively large,the gain of the peak power for different pulses is obviously different｜ with Super Gaussian pulse the largest followed by Gaussian pulse and Hyperbolic-Secant pulse and Lorentzian pulse the smallest.