Subwavelength imaging and control of ultrafast optical near-field under resonant- and off-resonant excitation of bowtie nanostructures
Subwavelength imaging and control of ultrafast optical near-field under resonant- and off-resonant excitation of bowtie nanostructures
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DOI：
10.1088/1367-2630/18/9/093046
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发表时间：
2016-09
影响因子：
3.3
通讯作者：
B. Ji;J. Qin;H. Tao;Z. Hao;Jingquan Lin
中科院分区：
文献类型：
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作者：
B. Ji;J. Qin;H. Tao;Z. Hao;Jingquan Lin
我们证明了亚波长成像和控制下的共振和非共振激发相同的金蝴蝶结纳米结构的局部近场分布，通过光电子发射电子显微镜。通过改变单个飞秒激光脉冲的偏振旋转和两个正交偏振飞秒激光脉冲的相位延迟来实现近场分布的控制。我们发现，本地化的光学近场分布可以很好地控制之间的角落的纳米棱镜的蝴蝶结共振激发或非共振激发的边缘。共振激励比非共振激励的情况下，实现了更好的PEEM图像的可视化。的光学近场分布控制的实验结果很好地再现了时域有限差分模拟和理解的电荷分布的蝴蝶结由s-和p-偏振光照明的线性组合。此外，通过旋转单个脉冲的偏振角和相干控制两个正交偏振的飞秒激光脉冲，可以实现相位反转或不变的近场激发位置的移动，或者不移动激发位置但仅反转近场的相位。
We demonstrate subwavelength imaging and control of localized near-field distribution under resonant and off-resonant excitation of identical gold bowtie nanostructures through photoemission electron microscopy. Control of the near-field distribution was realized by polarization rotation of single femtosecond laser pulse and variation of the phase delay of two orthogonally polarized femtosecond laser pulses. We show that the localized optical near-field distribution can be well controlled either among the corners of the nano-prisms in the bowtie for resonant excitation or the edges for off-resonant excitation. A better visualization of the PEEM image is achieved for resonant excitation than in the case of off-resonant excitation. The experimental results of the optical near-field distribution control are well reproduced by finite-difference time-domain simulations and understood by linear combination of electric charge distribution of the bowtie by s- and p- polarized light illumination. In addition, a shift of the near-field excitation position with inverted or unchanged phase, alternatively an un-shift of the excitation position but only with inverted phase of the near-field, can be realized by rotating the polarization angle of a single pulse and coherent control of two orthogonally polarized fs laser pulses.