The role of preceding surface morphology in LIPSS generation on silicon

Femtosecond laser processing is a potent tool for surface micro/nano-structuring, wherein laser-induced periodic surface structures (LIPSS) have emerged as one of the most prominent enabling technologies in this field due to their broad prospects for functional applications. However, incomplete understanding of the formation process and multi-pulse mechanisms constrains their further development, primarily manifested in limited structural uniformity and insufficient morphological controllability. Based on a systematic investigation of the cumulative effects of laser pulses and the evolution of silicon surface morphology, this study reveals the three-stage evolution of LIPSS, encompassing micro-crater formation, periodic structure growth, and over-ablation. Furthermore, it demonstrates that the preceding surface morphology serves as an important factor governing the evolution of subsequent periodic structures. Simultaneously, we further elucidated the formation mechanism of the amorphous ring and the evolution of the crystalline phase during the formation of LIPSS. Building on this mechanistic insight, two novel control strategies are demonstrated. First, pre-designed periodic micro-grooves fabricated by single-point diamond turning (SPDT) are employed as deterministic optical templates, successfully guiding LIPSS orientation and morphology beyond the traditional polarization-governed paradigm. Second, an inter-pulse feedback method is developed to significantly enhance the large-area uniformity of low-spatial-frequency LIPSS (LSFL). This work advances the fundamental understanding of LIPSS genesis by establishing a systematic correlation between surface morphology evolution, electric-field redistribution, and crystalline phase transformation during multi-pulse LIPSS formation. It further provides practical pathways for deterministic fabrication, paving the way for more reliable applications in optics, tribology, and sensing.