On-Chip Control of Electron Emission with an Active Terahertz Metasurface

Terahertz (THz) radiation has emerged as a powerful tool for inducing ultrafast electron emission and controlling electron beams, with applications in photonics and electron microscopy. Here, the first realization of on-chip electron emission control using an active THz metasurface is reported. The device integrates resonant dipole antennas and bias arms on a fused silica substrate, enabling precise modulation of electron trajectories through electrostatic control. Experimental results, supported by particle-in-cell simulations, reveal that electron emission via Fowler–Nordheim tunneling can be dynamically steered by varying the applied bias. A positive bias suppresses emission by attracting electrons to the bias arms, while a negative bias repels them, allowing trajectory control and the emergence of new emission features. Time-of-flight measurements show distinct shifts in electron emission behavior, with strong correlation to bias voltage and THz field strength. This work demonstrates a practical approach to integrating ultrafast electron control into chip-scale systems.