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对不同抽运方式下光子晶体光纤飞秒脉冲放大器中的脉冲演变过程进行了数值模拟和实验验证。在数值模拟上,采用了速率方程和非线性薛定谔方程相结合的理论模型;该模型考虑到端面抽运引起光纤中的非均匀增益分布、群速度色散和自相位调制三者之间的相互作用。模拟结果表明,相比于前向抽运放大方式,采用背向抽运放大方式不仅输出功率高,而且放大脉冲具有更窄的时域和光谱宽度,即较小的时间带宽积和更少的非线性积累。在验证实验上,搭建了基于前向和背向抽运方式的光子晶体光纤飞秒激光放大器;获得的实验结果与数值模拟结论一致,并对放大脉冲演变过程的物理机制进行了讨论。
The pulse evolution process in photonic crystal fiber femtosecond pulse amplifier under different pumping modes is numerically simulated and experimentally verified. In the numerical simulation, a theoretical model combining the rate equation with the nonlinear Schrödinger equation is adopted. The model considers the interaction between the non-uniform gain distribution in fiber, the group velocity dispersion and the self-phase modulation . The simulation results show that, compared with the forward pumped amplification, the backward pumped amplification not only has high output power, but also has a narrower time-domain and spectral width, ie smaller time-bandwidth product and less Non-linear accumulation. In the verification experiment, we build a photonic crystal fiber femtosecond laser amplifier based on forward and backward pumping modes. The experimental results are consistent with the numerical simulation results and the physical mechanism of the amplification pulse evolution process is discussed.