Zhang Fangteng, Nie Zhaogang, Huang Huixiang, Ma Lin, Tang Hui, Hao Mingming, Qiu Jianrong
Opt Express. 2019 Mar 4;27(5):6442-6450. doi: 10.1364/OE.27.006442.
In-volume, self-assembled, three-dimensional, periodic micro-nano structures are induced in quartz crystal by tightly focused, 500-kHz femtosecond laser pulses. With suitable pulse energy, three different types of periodic structures can be observed in modified regions using scanning electron microscopy. The first one with period (Λ) of ~400 nm in the direction of the laser polarization, i.e. nanograting, shows indicative features similar to that in fused silica. The second one with period (Λ) in the scan direction and the third one with period (Λ) in the laser propagation direction are both equally spaced by ~1 μm, which is close to the laser wavelength. Moreover, the structure with period (Λ) covers almost the whole cross-section of modified regions, which is distinctive to that observed in fused silica. Through the comparison of the structures induced by 1-kHz pluses and those by 500-kHz pluses, we deduce that the heat accumulation effect may have a positive influence on the formation of nanogratings in quartz crystal.
通过聚焦紧密的500千赫兹飞秒激光脉冲，在石英晶体中诱导出了体内自组装的三维周期性微纳结构。在合适的脉冲能量下，使用扫描电子显微镜可以在改性区域观察到三种不同类型的周期性结构。第一种在激光偏振方向上周期（Λ）约为400纳米，即纳米光栅，显示出与熔融石英中类似的指示性特征。第二种在扫描方向上具有周期（Λ），第三种在激光传播方向上具有周期（Λ），两者的间距均约为1微米，这接近激光波长。此外，周期（Λ）的结构几乎覆盖了改性区域的整个横截面，这与在熔融石英中观察到的情况不同。通过比较1千赫兹脉冲和500千赫兹脉冲诱导的结构，我们推断热积累效应可能对石英晶体中纳米光栅的形成有积极影响。
