Phase and polarization-controlled strong near-field electron dynamics at isolated nanoparticles

具有良好定义的载波包络相位（CEP）的少周期激光脉冲已被证明是控制纳米尺度系统（如纳米颗粒，纳米尖端和具有阿秒分辨率的表面组装纳米结构）中的电子强场过程的重要工具。我们的初步工作孤立的电介质纳米球显示的CEP控制强近场诱导的加速过程的鲁棒性定制的近场的强度制度，其中非线性电荷相互作用响应显着有助于加速过程。在这个建议中，我们的目标是通过利用激光场偏振的子周期控制来扩展近场动力学的波形控制。精确控制少周期单色或双色激光场偏振方向的一个关键优点是，强场驱动动力学的时间演化可以与角分辨光电发射分布相关联。拟议的工作的主要目标包括时间分辨的研究强场致发射从纳米系统，子周期分辨跟踪的纳米材料的光学响应，和子周期控制的直接和背散射电子在纳米尺度。更具体地说：1）我们将向孤立的纳米颗粒施加近圆偏振的几个周期的激光场，并将光电发射投影成像到偏振平面上。从角分辨分布获得的信息将用于光电发射过程的动量-时间映射。通过这种方法，我们的目标是时间分辨的电子发射从固体中的非绝热隧道regime.2）我们计划利用子周期瞬态的偏振形状的激光场跟踪近场响应的纳米系统成像的强场诱导的光电发射。我们将具有相反螺旋度的基波和二次谐波圆偏振激光脉冲进行联合收割机组合，以获得三叶草形激光场。三叶草形场最大值的方向由基波和二次谐波脉冲的相对相位确定，因此敏感地取决于材料在这些频率下的光学响应。我们将利用这种技术研究孤立纳米粒子在强场区的光学响应。3）我们提出利用在维斯和NIR光谱区的线偏振和圆偏振的几个周期的激光脉冲来探索孤立纳米粒子和团簇的电子光致发射的光学控制。随着直接和背散射电子发射的方向控制，我们的目标是创建孤立的阿秒电子爆发的同步束。从激光-物质相互作用的基本观点和超短电子脉冲在超快纳米电子学和显微镜中的应用来看，光学控制电子的纳米级源可能是令人感兴趣的。

Few-cycle laser pulses with well-defined carrier-envelope phase (CEP) have proven to be an essential tool for controlling electronic strong-field processes in nanoscale systems such as nanoparticles, nanotips, and surface assembled nanostructures with attosecond resolution. Our preliminary work on isolated dielectric nanospheres shows the robustness of the CEP controlled strong near-field-induced recollision process in tailored near-fields up to the intensity regime where the nonlinear charge interaction response significantly contributes to the acceleration process. In this proposal we aim to extend the waveform control of the near-field dynamics by utilizing sub-cycle control of the laser field polarization. One of the key advantages of the precise control of the polarization direction of few-cycle single or two color laser fields is that the time evolution of the strong field driven dynamics can be correlated with the angle-resolved photoemission distribution. Major goals of the proposed work include time-resolved studies of strong field induced emission from nanoscopic systems, sub-cycle resolved tracing of the optical response of nanoscopic materials, and the sub-cycle control of the direct and backscattered electrons at the nanoscale. More specifically:1) We will apply near circularly polarized few-cycle laser fields to isolated nanoparticles and image the photoemission projection onto the polarization plane. Information obtained from the angle-resolved distributions will be utilized for momentum-to-time mapping of the photoemission process. With this approach we aim to time-resolve the electron emission from solids in the nonadiabatic tunneling regime.2) We plan to utilize sub-cycle transients of polarization-shaped laser fields to trace the near-field response of nanoscopic systems by imaging the strong field induced photoemission. We will combine the fundamental and second harmonic circular polarized laser pulses with opposite helicity to obtain a cloverleaf shaped laser field. The direction of the cloverleaf shaped field maxima is determined by the relative phase of fundamental and second harmonic pulses and thus depends sensitively on the optical response of the material at these frequencies. We will apply this technique for the investigation of the optical response of isolated nanoparticles in strong-field regime.3) We propose to utilize few-cycle laser pulses of linear and circular polarization in VIS and NIR spectral regions to explore optical control of the electron photoemission from isolated nanoparticles and clusters. With the directional control of the direct and back-scattered electron emission we aim for the creation of synchronized beams of isolated attosecond bursts of electrons. A nanoscopic source of optically controlled electrons can be of interest from the fundamental perspective of laser-matter interaction and in view of applications in ultrafast nanoelectronics and microscopy with ultrashort electron pulses.