Publications by authors named "Jian-Wu Yao"
The femtosecond laser ablation of silicon surface near the ablation threshold was investigated and the preferential ablation along different directions was observed in different stages. It was found that the ripples formed in the initial stage facilitate the ablation along the direction perpendicular to the ripples, leading to the formation of an elliptical ablation area. With increasing length and depth of the ripples, however, nanohole arrays formed in the ripples will modify the distribution of electric field which benefits the ablation along the direction parallel to the ripples.
View Article and Find Full Text PDFWe report on the formation of one- and two-dimensional (1D and 2D) nanohole arrays on the surface of a silicon wafer by scanning with a femtosecond laser with appropriate power and speed. The underlying physical mechanism is revealed by numerical simulation based on the finite-difference time-domain technique. It is found that the length and depth of the initially formed gratings (or ripples) plays a crucial role in the generation of 1D or 2D nanohole arrays.
View Article and Find Full Text PDFArticle Synopsis
- Researchers explored how femtosecond laser pulses create high spatial frequency periodic structures on metal surfaces through both experiments and simulations.
- They found that initial low spatial frequency structures change the electric field distribution, which is essential for forming the finer patterns.
- When grooved areas on the metal become deep enough, the field intensity shifts to the ridges between grooves, causing them to ablate and resulting in high spatial frequency structures, as confirmed by their simulations and tests on materials like stainless steel and nickel.