Attosecond waveform engineering via spectral–temporal coupled high-harmonic generation

The attosecond waveform in high-harmonic generation (HHG) exhibits intricate spectral–temporal structures owing to the abundant coupling effect during laser–matter interaction. In this article, we present a flexible method for coherent attosecond waveform control leveraging propagation-induced spectral structure in high harmonics. By engineering these spectral features, we achieve precise temporal modulation and characterization of attosecond pulse trains (APTs). The intrinsic association between this unique spectral–temporal structure and macroscopic propagation effects is verified under three-dimensional simulation analysis. It establishes an intuitive connection between spectral and temporal manifestations of attosecond pulses, while pioneering a straightforward approach for coherently manipulating the waveform of the tabletop attosecond light sources.