Competition between ponderomotive acceleration and attosecond chirps in optimizing attosecond pulse generation in solids

A practical approach is proposed for efficiently generating ultrashort attosecond pulses (APs) from realistic solid-state materials, aiming to achieve pulse widths comparable to those generated in gases. This approach focuses on modulating the plateau region of the high harmonic spectrum by adjusting the peak vector potential of laser fields through changing photon energy, while maintaining a constant peak electric field. It initiates a competition between heightened ponderomotive acceleration and the attosecond chirp effect, leading to a non-monotonic variation in both intensity and duration of the generated APs. Using hexagonal boron nitride as a prototypical material, we demonstrate the generation of optimal ultrashort pulses with a full width at half maximum (FWHM) of 143 attoseconds, marking an updated record for the shortest pulse duration from solid-state sources. This strategy shows promise for application across a broad range of materials, offering new pathways to promote high harmonic performance.