Imaging ultrafast processes in femtosecond (fs) laser–material interactions such as fs laser ablation is very important to understand the physical mechanisms involved. To achieve this goal with high resolutions in both spatial and temporal domains, a combination of optical pump–probe microscopy and structured illumination microscopy can be a promising approach, but suffers from the multiple-frame method with a phase shift that is inapplicable to irreversible ultrafast processes such as ablation. Here, we propose and build a wide-field single-probe structured light microscopy (SPSLM) to image the ultrafast three-dimensional topography evolution induced by fs lasers, where only a single imaging frame with a single structured probe pulse is required for topography reconstruction, benefiting from Fourier transform profilometry. The second harmonic of the fs laser is used as the structured probe light to improve spatial lateral resolution into the subwavelength region of ～478 nm, and the spatial axial and temporal resolutions are estimated to be ～22 nm and ～256 fs, respectively. With SPSLM, we successfully image the ultrafast topography evolution of a silicon wafer surface impacted by single and multiple fs pulses. The variable formation and evolution of the laser induced periodic surface structures during an ultrashort time are visualized and analyzed. We believe that SPSLM will be a significant approach for revealing and understanding various ultrafast dynamics, especially in fs laser ablation and material science.

Jie Xu;Changjun Min;Yuquan Zhang;Jielei Ni;Gengwei Cao;Qianyi Wei;Jianjun Yang;Xiaocong Yuan

Nanophotonics Research Center, Shenzhen Key Laboratory of Micro-Scale Optical Information Technology & Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China;State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;e-mail: cjmin@szu.edu.cn;e-mail: yqzhang@szu.edu.cn;e-mail: xcyuan@szu.edu.cn

光子学研究（英文）

[1]Jie Xu;Changjun Min;Yuquan Zhang;Jielei Ni;Gengwei Cao;Qianyi Wei;Jianjun Yang;Xiaocong Yuan-.Imaging ultrafast evolution of subwavelength-sized topography using single-probe structured light microscopy)[J].光子学研究（英文）,2022(08):1900

SPSLM

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