Solitary beam propagation in periodic layered Kerr media enables high-efficiency pulse compression and mode self-cleaning

Generating intense ultrashort pulses with high-quality spatial modes is crucial for ultrafast and strong-field science and can be achieved by nonlinear supercontinuum generation(SCG)and pulse compression.In this work,we propose that the generation of quasi-stationary solitons in periodic layered Kerr media can greatly enhance the nonlinear lightmatter interaction and fundamentally improve the performance of SCG and pulse compression in condensed media.With both experimental and theoretical studies,we successfully identify these solitary modes and reveal their unified condition for stability.Space-time coupling is shown to strongly influence the stability of solitons,leading to variations in the spectral,spatial and temporal profiles of femtosecond pulses.Taking advantage of the unique characteristics of these solitary modes,we first demonstrate single-stage SCG and the compression of femtosecond pulses from 170 to 22 fs with an efficiency>85%.The high spatiotemporal quality of the compressed pulses is further confirmed by highharmonic generation.We also provide evidence of efficient mode self-cleaning,which suggests rich spatiotemporal self-organization of the laser beams in a nonlinear resonator This work offers a route towards highly efficient,simple,stable and highly flexible SCG and pulse compression solutions for state-of-the-art ytterbium laser technology.

Phase-Matched High-Harmonic Generation under Nonadiabatic Conditions:Model and Experiment

Nonadiabatic phase matching of high-harmonic generation(HHG)driven by few-cycle laser pulses is essential for extending harmonic energy and generating isolated attosecond pulses.However,understanding nonadiabatic HHG is challenging due to the complex interplay of various optical phases driven by temporally and spatially varying laser fields.Theoretical calculations typically rely on computationally demanding 3-dimensional simulations,which can make it difficult to extract the essential features of nonadiabatic HHG.In this work,we develop a computationally efficient 2-dimensional model that directly considers various phase contributions of HHG.Our model can well explain the experimentally observed pressure-and intensity-dependent behaviors of different harmonic orders.By appropriately parameterizing the single-atom response,our model can also estimate the variation of HHG spectra under different driving conditions.Our model can provide an efficient tool for the design and optimization of HHG-based applications.