Harness Propagating and Evanescent Waves by Metasurfaces

In this talk, I will discuss our work of employing metasurfaces to harness both propagating and evanescent waves, which promise efficient, miniaturized and multifunctional devices for optical imaging, sensing, and information processing. First, I will present a new concept of chiral metamirrors, which can achieve near-perfect reflection of designated circularly polarized light without reversing its handedness, yet complete absorption of the other polarization state. Such a metasurface can be used for polarimetric imaging to extract the polarization information of light. Recently, we have adopted deep learning to accelerate the design of chiral metamaterials with prescribed chiroptical responses. Our results demonstrate that the data-driven approach can help to unveil the highly nonintuitive and nonlinear structure-property relationship in metamaterials. Finally, I will present designer metasurfaces that can efficiently control the polarization and trajectory of Smith-Purcell emission from moving charged particles, by coupling the evanescent waves of particles with the inherent electric and magnetic dipoles of the metasurface. These findings may open a new door to design electron-beam-induced light sources with high efficiency and a compact footprint.