Smith-Purcell radiation (SPR) provides a powerful platform for manipulating light at the nanoscale across a broad spectral range. In this study, we demonstrate SPR modulation using a two-dimensional metallic chirped metagrating (CMG) composed of nanowires with a gradually varying separation along the groove direction. By simply shifting the electron beam along this direction, without altering the grating structure, we achieve multiple functionalities, including tunable emission angles, adjustable focal positions, dual-focus control, and dual-wavelength emission. Experimental validation through CMG fabrication and angle-resolved cathodoluminescence measurements confirms effective control of SPR dispersion via electron beam positioning. We further extend this concept to electron sheet excitation and demonstrate the generation of focused vortex SPR. This work offers a robust and reconfigurable strategy for developing tunable nanoscale light sources.

Close

PrevNext

View figure in article

• Electron beams & optics
• Electron emission
• Light-matter interaction
• Metagratings
• Metamaterials
• Optical & microwave phenomena
• Finite-difference time-domain method