Generation of Accelerating Waves in Smith-Purcell Radiation

TL;DR

This paper demonstrates that by interacting with bianisotropic metasurfaces, moving electrons can generate accelerating Smith-Purcell radiation, enabling the creation of Airy beams with unique propagation properties.

Contribution

It introduces a novel method to generate accelerating waves using bianisotropic metasurfaces interacting with electrons, expanding the capabilities of Smith-Purcell radiation.

Findings

Full amplitude and phase control of Smith-Purcell radiation achieved.

Airy beams with parabolic trajectories generated.

Experimental evidence of evanescent field coupling into accelerating waves.

Abstract

Metasurface has recently emerged as a powerful platform to engineer wave packets of free electron radiation at the mesoscale. Here, we propose that accelerating waves can be generated when moving electrons interact with an array of bianisotropic meta-atoms. By changing the intrinsic coupling strength, we show full amplitude coverage and 0-to-{\pi} phase switching of Smith-Purcell radiation from bianistropic meta-atoms. This unusual property leads to the creation of Airy beams that shifts along a parabolic trajectory during propagation. Experimental implementation displays that evanescent fields bounded at slotted waveguides can be coupled into accelerating waves via Smith-Purcell radiation from a designer bianisotropic metasuface. Our results offer an alternative route towards free electron lasers with diffraction-free, self-accelerating, and self-healing beam properties.