Qiao Hongzhen, Yang Jianjun, Li Jing, Liu Qi, Liu Jie, Guo Chunlei
School of Electronic and Electrical Engineering, Shangqiu Normal University, Shangqiu 476000, China.
State Key Laboratory of Applied Optics, Changchun Institute of Modern Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
Materials (Basel). 2018 Nov 26;11(12):2380. doi: 10.3390/ma11122380.
We present a mask-free strategy for fabricating two-dimensional subwavelength periodic triangular arrays on tungsten, by focusing two orthogonally polarized and temporally delayed femtosecond laser beams using a cylindrical lens. In stark contrast to the commonly observed structures of either a single ablation spot or a one-dimensional grating, we obtained highly uniform periodic triangular arrays on the laser-exposed surface, with three equilateral sides each of 480 nm in length and about 100 nm in modulation depth. The triangular features varied with both the laser energy and the scanning speed. We found that the optical reflectivity of such a surface reduces significantly within the spectral range of 700⁻2500 nm. The triangular structure morphology can also be controlled by varying the time delay between the two laser beams.
我们提出了一种无掩膜策略，通过使用柱面透镜聚焦两束正交偏振且具有时间延迟的飞秒激光束，在钨上制备二维亚波长周期性三角形阵列。与通常观察到的单个烧蚀点或一维光栅结构形成鲜明对比的是，我们在激光照射表面获得了高度均匀的周期性三角形阵列，其三条等边每条边长为480 nm，调制深度约为100 nm。三角形特征随激光能量和扫描速度而变化。我们发现，这种表面的光学反射率在700⁻2500 nm光谱范围内显著降低。通过改变两束激光束之间的时间延迟，也可以控制三角形结构的形态。
