Adel P, Engelbrecht M, Wandt D, Fallnich C
Opt Express. 2005 Dec 12;13(25):10260-5. doi: 10.1364/opex.13.010260.
We present experimental results, which show that the up-chirp of dispersively stretched femtosecond pulses decreases linearly with increasing pulse energy after amplification in Erbium-doped fibers. For 6 microJ output pulses a nonlinear dispersion of -410(6) fs(2) was measured. This nonlinear dispersive effect is attributable to the resonant dispersion of the Erbium-ions and the decrease of the inversion during pulse amplification and was about one order of magnitude larger than predicted by the literature. Most likely this deviation is attributable to the complex population dynamics of the Er3+-ions during pulse amplification, since in the literature the relation between the refractive index and Er3+-inversion was described for a quasi-static population distribution. Due to the high resonant dispersion the required compressor dispersion for minimum output pulse duration depends strongly on the output pulse energy in Erbium-doped fiber-based chirped-pulse-amplifier set-ups.
我们展示了实验结果，结果表明，在掺铒光纤中放大后，色散展宽的飞秒脉冲的向上啁啾随脉冲能量增加而线性减小。对于6微焦的输出脉冲，测量到的非线性色散为-410(6)飞秒²。这种非线性色散效应归因于铒离子的共振色散以及脉冲放大过程中反转的降低，并且比文献预测的大约大一个数量级。这种偏差很可能归因于脉冲放大过程中Er³⁺离子复杂的布居动力学，因为文献中描述的折射率与Er³⁺反转之间的关系是针对准静态布居分布的。由于高共振色散，在基于掺铒光纤的啁啾脉冲放大器装置中，实现最小输出脉冲持续时间所需的压缩器色散强烈依赖于输出脉冲能量。
