Dynamic process of ultrashort-pulse laser pumped nanostructure formation in attosecond time scale and its application

通过时间分辨测量，我们证明了在飞秒激光脉冲照射下，电介质、半导体和金属表面上周期性纳米结构的形成是由表面等离子激元（SPPs）的激发主导的。模拟纳米结构的物理过程，我们开发了一种新的烧蚀技术来控制空间SPP波模式的激发，并直接在空气中的固体表面上刻印均匀的纳米光栅。基于这一机理，我们还发现利用波长较短的激光可以缩短纳米光栅的周期。因此，本项目成功地开发了一种新的纳米加工的基本原理和技术，可以用激光制造超过衍射极限的纳米光栅。

We have demonstrated that periodic nanostructure formation on dielectric, semiconductor, and metal surfaces irradiated with femtosecond laser pulses is dominated by the excitation of surface plasmon polaritons (SPPs), through the time-resolved measurements. Modeling the physical process of nanostructuring, we have developed a new ablation technique to control the excitation of spatial SPP wave modes and directly imprint a homogeneous nanograting on solid surfaces in air. It is also shown, based on the mechanism, that the nanograting period can be reduced by making use of shorter-wavelength lasers. Thus this project has successfully developed the fundamental principle and technique of a new nanoprocessing that can fabricate nanogratings with lasers beyond the diffraction limit.