Seiffert L, Süßmann F, Zherebtsov S, Rupp P, Peltz C, Rühl E, Kling M F, Fennel T
1Institut für Physik, Universität Rostock, 18051 Rostock, Germany.
2Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
Appl Phys B. 2016;122(4):101. doi: 10.1007/s00340-016-6369-0. Epub 2016 Apr 12.
Nanostructures exposed to ultrashort waveform-controlled laser pulses enable the generation of enhanced and highly localized near fields with adjustable local electric field evolution. Here, we study dielectric SiO nanospheres ( = 100-700 nm) under strong carrier-envelope phase-controlled few-cycle laser pulses and perform a systematic theoretical analysis of the resulting near-field driven photoemission. In particular, we analyze the impacts of charge interaction and local field ellipticity on the near-field driven electron acceleration. Our semiclassical transport simulations predict strong quenching of the electron emission and enhanced electron energies due to the ionization induced space charge. Though single surface backscattering remains the main emission process for the considered parameter range, we find a substantial contribution of double rescattering that increases with sphere size and becomes dominant near the cutoff energy for the largest investigated spheres. The growing importance of the double recollision process is traced back to the increasing local field ellipticity via trajectory analysis and the corresponding initial to final state correlation. Finally, we compare the carrier-envelope phase-dependent emission of single and double recollision electrons and find that both exhibit a characteristic directional switching behavior.
暴露于超短波形控制激光脉冲的纳米结构能够产生增强的、高度局部化的近场，且局部电场演化可调节。在此，我们研究了在强载波包络相位控制的少周期激光脉冲作用下的介电SiO纳米球（直径 = 100 - 700 nm），并对由此产生的近场驱动光发射进行了系统的理论分析。特别是，我们分析了电荷相互作用和局部场椭圆率对近场驱动电子加速的影响。我们的半经典输运模拟预测，由于电离诱导的空间电荷，电子发射会强烈猝灭，电子能量会增强。虽然单表面背散射在考虑的参数范围内仍是主要的发射过程，但我们发现双重散射有显著贡献，其随着球尺寸的增加而增加，并且对于最大的研究球体，在截止能量附近成为主导。通过轨迹分析和相应的初态到末态相关性，双重碰撞过程重要性的增加可追溯到局部场椭圆率的增加。最后，我们比较了单重和双重碰撞电子的载波包络相位相关发射，发现两者都表现出特征性的方向切换行为。
