Near-Field Electron Ptychography of Metasurfaces

Metasurfaces, engineered interfaces composed of subwavelength artificial structures [1], have revolutionized the control of light. Their functionality relies on dense arrangements of dielectric or metallic nanoantennas, which enable precise control over local phase, refraction, and reflection. The nanoantennas size and resonance properties are specially tailored to control light by exploiting geometric phases. Such capabilities enable metasurface-based applications in advanced imaging, sensing, communication, and energy harvesting [2]. A detailed understanding of metasurfaces' complex near-fields is essential for optimizing and expanding their potential applications.