Coupling Broadband Terahertz Dipoles to Microscale Resonators

Optically driven spintronic emitters are a unique class of terahertz (THz) sources due to their quasi-two-dimensional geometry and thereby their capability to effectively couple to resonator near fields. Global excitation of the emitters often obstructs the intricate details of the coupling mechanisms between local THz dipoles and the individual modes of resonator structures. Here, we demonstrate the spatial mapping of the coupling strength between a micrometer-scale terahertz source on a spintronic emitter and far-field light mediated by a structured metallic environment. For a bow-tie geometry, experimental results are reproduced by a numerical model, providing insights into the microscopic coupling mechanisms. The broad applicability of the technique is showcased by extracting the THz mode structure in split-ring resonator metasurfaces and linear arrays. With these developments, planar THz sources with tailored spectral and angular emission profiles become accessible

Highly Coherent Femtosecond Electron Pulses for Ultrafast Transmission Electron Microscopy

We describe the implementation and detailed characterization of a laser-triggered field-emitter electron source integrated into a modified transmission electron microscope. Highly coherent electron pulses enable high resolution ultrafast electron imaging and diffraction

Coupling Broadband Terahertz Dipoles to Microscale Resonators

Optically driven spintronic emitters are a unique class of terahertz (THz) sources due to their quasi-two-dimensional geometry and thereby their capability to effectively couple to resonator near fields. Global excitation of the emitters often obstructs the intricate details of the coupling mechanisms between local THz dipoles and the individual modes of resonator structures. Here, we demonstrate the spatial mapping of the coupling strength between a micrometer-scale terahertz source on a spintronic emitter and far-field light mediated by a structured metallic environment. For a bow-tie geometry, experimental results are reproduced by a numerical model, providing insights into the microscopic coupling mechanisms. The broad applicability of the technique is showcased by extracting the THz mode structure in split-ring resonator metasurfaces and linear arrays. With these developments, planar THz sources with tailored spectral and angular emission profiles become accessible

Generation and attosecond shaping of high coherence free-electron beams for ultrafast TEM

We demonstrate the generation and optical control of ultrashort high-coherence electron pulses. The free-electron quantum state is phase-modulated in the longitudinal and transverse dimensions, and the formation of attosecond electron pulse trains is quantitatively probed

Generation and attosecond shaping of high coherence free-electron beams for ultrafast TEM

We demonstrate the generation and optical control of ultrashort high-coherence electron pulses. The free-electron quantum state is phase-modulated in the longitudinal and transverse dimensions, and the formation of attosecond electron pulse trains is quantitatively probed