UC Berkeley

Metamaterials are artificial materials that consist of subwavelength unit cells (meta-atoms). They attain their electromagnetic properties from the unit cell response rather than the constituent materials, and can be designed to exhibit properties that are not readily found in natural materials. In the past decade, the study of metamaterials has opened up a route to many exciting applications, such as superresolution imaging and invisibility cloaks.

In recent years, metasurfaces, which can be considered as two-dimensional metamaterials, have attracted intensive research interests. Due to their reduced dimensionality, metasurfaces are much easier to fabricate and yet offer a higher degree of freedom in molding the flow of waves (optical, acoustic), compared to bulk metamaterials. Being optically thin, metasurface has reduced absorptive loss and thus offers higher efficiency. Metasurfaces utilize resonances to achieve abrupt phase shifts on subwavelength scale distances, in contrast to traditional optical devices that rely on propagation effect.

We are interested in investigating non-conventional interactions between light and meta-atoms. We show that by introducing novel types of light-matter interactions mediated by metamaterials, new degrees of freedoms can be elevated for precise controlling of light and matter at the nanoscale.

This dissertation consists of three independent studies: 1. We design a color sorting metasurface under the regime where neighboring meta-atoms are strongly coupled. The coupling enabled enhanced quality factor and reduced detrimental crosstalk, leading to a color sensor with a pixel size below the diffraction limit. 2. We study the interaction of metasurface with quantum light. By engineering the quantum vacuum by a phase gradient metasurface, we theoretically show that quantum interference and coherence and be induced in emitter transitions. 3. We investigate the magnetic interactions between light and meta-atoms that exhibit artificial optical magnetism, and perform the first demonstration that magnetic interactions can be applied to trap and manipulate nanoscopic particles.