High-energy femtosecond laser pulse compression in single- and multi-ionization regime of rare gases: experiment versus theory

We report experimental and numerical results on the post-compression of 40 fs duration pulses down to 10 fs at high energy level (multi-mJ). The spectral broadening is achieved through the self-phase modulation resulting from optical-field-ionization of different noble gases (He, Ne, Ar) by the 40-fs laser pulse propagating in a low-pressure gas-filled hollow capillary. We discuss the influence of the multi-ionization dynamics, through the gas dependence, on the laser energy carried by the capillary, as well as on the duration and temporal shape of the post-compressed pulses. In all the different experimental conditions investigated in this article (pressures and gases used), the experimental data is in good agreement with the numerical results from a three-dimension propagation code. Through this study, we demonstrate the robustness of the proposed post-compression technique with regard to multi-ionization, indicating that it can be used on a large intensity range by judiciously choosing the gas.