Laser-induced field emission from a tungsten nanotip by circularly polarized femtosecond laser pulses
Laser-induced field emission from a tungsten nanotip by circularly polarized femtosecond laser pulses
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DOI：
10.1103/physrevb.101.045406
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发表时间：
2020-01
影响因子：
3.7
通讯作者：
Hirofumi Yanagisawa;T. Greber;C. Hafner;J. Osterwalder
中科院分区：
文献类型：
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作者：
Hirofumi Yanagisawa;T. Greber;C. Hafner;J. Osterwalder
我们研究了圆偏振飞秒激光脉冲诱导的钨纳米尖端电子的发射模式和能谱。观察到不同螺旋度的圆偏振的发射图案的变化，而能谱几乎保持相同。这种发射模式差异背后的物理原理是尖端顶点表面电磁波传播方向的变化。能谱显示出与强场状态下的线偏振激光相同的光谱特征，即低能量峰和平台特征。低能量峰是由于相对于即时发射而言延迟的电子发射。实验数据和等离子体模拟支持了我们之前的结论，即观察到的延迟发射过程源于非弹性重散射过程。这项工作表明，使用圆偏振是添加额外旋钮来控制纳米尖端在纳米和飞秒尺度上的空间和时间发射的简单方法。它可以作为螺旋驱动的子周期光开关得到应用。
We have investigated emission patterns and energy spectra of electrons from a tungsten nanotip induced by circularly polarized femtosecond laser pulses. Variations of emission patterns were observed for different helicities of circular polarization while the energy spectra remained almost identical. The physics behind this difference in emission patterns is the change in propagation directions of surface electromagnetic waves on the tip apex. The energy spectra showed the same spectroscopic signatures as the linearly polarized laser in a strong-field regime, which are a low-energy peak and a plateau feature. The low-energy peak is due to a delayed electron emission with respect to a prompt emission. The experimental data and plasmonic simulations support our previous conclusion, where the observed delayed emission processes originate from an inelastic rescattering process. This work demonstrates that the use of circular polarization is an easy means to add extra knobs to control the spatial and temporal emission from a nanotip at the nanometer and femtosecond scale. It could find applications as a helicity-driven subcycle optical switch.