Nanostructures for vacuum optoelectronic engineering

Abstract

The interaction between free electrons and electromagnetic fields enables a wide range of scientific research and technological applications, ranging from electronic, optoelectronic, and microwave vacuum tubes, to electron beams for material processing and analysis, particle accelerators, and free-electron radiation sources. However, for most free-electron-based devices, the compactness, chip-scale integration, ultrafast temporal response, and quantum state manipulation remain impractical or unexplored. Recent advances in nanofabrication have pushed the boundary and extended the operating paradigm of free-electron devices. In this thesis, I will investigate the interplay between free electrons and optical frequency electromagnetic fields mediated by nanostructures. I will show high-yield, ultrafast, surface-plasmon-enhanced photoelectron emitters. With the photoemission driven by the optical field, this technology enables the detection of carrier-envelope-phase of ultrafast optical pulses with solid-state nanoantenna arrays integrated on a chip. Additionally, I will show free-electron-driven plasmon and photon emission from nanophotonic structures, which leads to the characterization of plasmonic nanostructures and the development of nanoscale tunable free-electron light sources. Furthermore, I will show the manipulation of free electrons with nanostructured phase plates, and propose an electron beam splitter design based on the quantum interaction-free measurement and quantum Zeno effect. The work demonstrated in this thesis presents a step towards chip-integrated petahertz optoelectronic devices, compact tunable free-electron radiation sources, as well as quantum devices for free electrons.