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

• Applicant: Dr. Sergey Zherebtsov
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 322422731

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.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Matthias Kling