Multipass cells (MPCs) are used nowadays as nonlinear tools to perform spectral broadening and temporal manipulation of laser pulses while maintaining a good spatial quality and spatio-spectral homogeneity. However, intensive 3D nonlinear spatio-temporal simulations are required to fully capture the physics associated with pulse propagation inside these systems. In addition, the limitations of such a scheme are still under investigation. In this study, we first establish a 1D model as a useful design tool to predict the temporal and spectral properties of the output pulse for nearly Gaussian beams, in a wide range of cavity configurations and nonlinearity levels. This model allows us to drastically reduce the computation time associated with MPC design. The validity of the 1D model is first checked by comparing it to 3D simulations. The results of the 1D model are then compared with experimental data collected from a near-concentric gas-filled multipass cell presenting a high level of nonlinearity, enabling the observation of wave breaking. In a second part, we experimentally characterize the spatio-spectral profile at the output of this experimental setup, both with an imaging spectrometer and with a complete 3D characterization method known as INSIGHT. The results show that gas-filled multipass cells can be used at peak power levels close to the critical power without inducing significant spatio-spectral couplings in intensity or phase.

中文翻译：

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多通道像元：一维数值模型和高非线性时空-光谱耦合研究

如今，多通道细胞（MPC）用作非线性工具，可在保持良好的空间质量和空间光谱均匀性的同时对激光脉冲进行光谱加宽和时间操纵。但是，需要大量的3D非线性时空模拟才能完全捕获与这些系统内部的脉冲传播相关的物理现象。另外，这种方案的局限性仍在研究中。在这项研究中，我们首先建立一维模型作为有用的设计工具，以预测在宽范围的腔结构和非线性水平下近高斯光束的输出脉冲的时间和频谱特性。该模型使我们能够大大减少与MPC设计相关的计算时间。首先通过将1D模型与3D仿真进行比较来检查其有效性。然后将一维模型的结果与从近同心充气多通道电池收集的实验数据进行比较，呈现出高水平的非线性，从而可以观察到波的破裂。在第二部分中，我们使用成像光谱仪和称为INSIGHT的完整3D表征方法，在此实验设置的输出处对空间光谱轮廓进行了实验表征。结果表明，充气多通道电池可在接近临界功率的峰值功率水平下使用，而不会引起强度或相位上显着的时空光谱耦合。我们使用成像光谱仪和称为INSIGHT的完整3D表征方法，在此实验设置的输出处实验性地描述了空间光谱轮廓。结果表明，充气多通道电池可在接近临界功率的峰值功率水平下使用，而不会引起强度或相位上显着的时空光谱耦合。我们使用成像光谱仪和称为INSIGHT的完整3D表征方法，在此实验设置的输出处实验性地描述了空间光谱轮廓。结果表明，充气多通道电池可在接近临界功率的峰值功率水平下使用，而不会引起强度或相位上显着的时空光谱耦合。