Generation of isolated white-light attosecond pulses in solids

Attosecond-pump attosecond-probe spectroscopy (APAP) is the key to understanding electronic-dominated dynamics in light-matter interactions. Although the feasibility of APAP has been demonstrated using isolated attosecond pulses (IAPs), the efforts are mainly confined to the ionization-induced dynamics triggered by the extreme ultraviolet and soft x-ray lights. However, the generation of IAPs capable of exciting neutral electronic excited states, which are more prevalent in nature, is still in its infancy, significantly limiting comprehensive insights into valence-electron wave packet dynamics. Here, we theoretically demonstrate a scheme for the straightforward and compact generation of white-light IAPs covering the visible and ultraviolet regions, based on solid-state high-harmonic generation. By analyzing the strong-field-induced electron-hole dynamics together with a saddle-point approximation, we unfold its microscopic generation mechanism. Furthermore, the feasibility and robustness of this approach are validated by the generation of IAPs from various materials under the same mechanism. Our work paves the way for generation of tabletop white-light IAP sources, thereby harnessing the widespread applications of APAP.