Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2a, D-12489 Berlin, Germany.
Nanotechnology. 2010 Apr 16;21(15):155302. doi: 10.1088/0957-4484/21/15/155302. Epub 2010 Mar 19.
An efficient way to generate nanoscale laser-induced periodic surface structures (LIPSS) in rutile-type TiO(2) with frequency-converted femtosecond laser pulses at wavelengths around 400 nm is reported. Extended-area structuring on fixed and moving substrates was obtained by exploiting the line focus of a cylindrical lens. Under defined conditions with respect to pulse number, pulse energy and scanning velocity, two types of ripple-like LIPSS with high and low spatial frequencies (HSFL, LSFL) with periods in the range of 90 nm and 340 nm, respectively, were formed. In particular, lower numbers of high energetic pulses favour the generation of LSFL whereas higher numbers of lower energetic pulses enable the preferential creation of HSFL. Theoretical calculations on the basis of the Drude model support the assumption that refractive index changes by photo-excited carriers are a major mechanism responsible for LSFL. Furthermore, the appearance of random substructures as small as 30 nm superimposing low spatial frequency ripples is demonstrated and their possible origin is discussed.
本文报道了一种在金红石型 TiO(2)中利用转换后的飞秒激光脉冲在 400nm 左右波长下生成纳米级激光诱导周期性表面结构（LIPSS）的有效方法。通过利用柱面透镜的线焦，可以在固定和移动的基底上进行大面积结构化处理。在脉冲数、脉冲能量和扫描速度方面定义了特定条件下，形成了两种具有高和低空间频率（HSFL、LSFL）的波纹状 LIPSS，其周期分别在 90nm 和 340nm 范围内。特别是，低能量脉冲的数量较多有利于 LSFL 的产生，而高能量脉冲的数量较多则有利于 HSFL 的优先产生。基于 Drude 模型的理论计算支持了这样的假设，即光激发载流子引起的折射率变化是产生 LSFL 的主要机制。此外，还证明了存在叠加在低空间频率波纹上的小至 30nm 的随机亚结构，并讨论了其可能的起源。
