Almeida G F B, Martins R J, Otuka A J G, Siqueira J P, Mendonca C R
Opt Express. 2015 Oct 19;23(21):27597-605. doi: 10.1364/OE.23.027597.
We investigated the effect of temporal shaped femtosecond pulses on silicon laser micromachining. By using sinusoidal spectral phases, pulse trains composed of sub-pulses with distinct temporal separations were generated and applied to the silicon surface to produce Laser Induced Periodic Surface Structures (LIPSS). The LIPSS obtained with different sub-pulse separation were analyzed by comparing the intensity of the two-dimensional fast Fourier Transform (2D-FFT) of the AFM images of the ripples (LIPSS). It was observed that LIPSS amplitude is more emphasized for the pulse train with sub-pulses separation of 128 fs, even when compared with the Fourier transform limited pulse. By estimating the carrier density achieved at the end of each pulse train, we have been able to interpret our results with the Sipe-Drude model, that predicts that LIPSS efficacy is higher for a specific induced carrier density. Hence, our results indicate that temporal shaping of the excitation pulse, performed by spectral phase modulation, can be explored in fs-laser microstructuring.
我们研究了时域整形飞秒脉冲对硅激光微加工的影响。通过使用正弦光谱相位，生成了由具有不同时间间隔的子脉冲组成的脉冲序列，并将其应用于硅表面以产生激光诱导周期性表面结构（LIPSS）。通过比较波纹（LIPSS）的原子力显微镜（AFM）图像的二维快速傅里叶变换（2D-FFT）强度，分析了不同子脉冲间隔下获得的LIPSS。结果表明，即使与傅里叶变换极限脉冲相比，对于子脉冲间隔为128 fs的脉冲序列，LIPSS幅度也更为突出。通过估计每个脉冲序列末尾达到的载流子密度，我们能够用Sipe-Drude模型解释我们的结果，该模型预测对于特定的诱导载流子密度，LIPSS效率更高。因此，我们的结果表明，通过光谱相位调制进行的激发脉冲时域整形可用于飞秒激光微结构化。
