UC Irvine

Metamaterials are composites that are engineered purposefully for realizing electromagnetic characteristics that do not occur naturally in mineral or organic form. These characteristics are realized by regular arrangements of meta atoms, the building blocks of metamaterials, that mimic the atoms in an element. The electric and magnetic responses of these building blocks are engineered in such a way that the effective permittivity and permeability of metamaterials can be tuned. Similarly, the anisotropy of constitutive electromagnetic parameters can also be controlled efficiently. This dissertation focuses on the enhancement of the interaction between light and matter using bulk anisotropic metamaterials and magnetic meta atoms, in order to enhance, control and/or isolate electric and magnetic nature of emitters. This is achieved first through utilization of hyperbolic metamaterials (HMs) which are a subcategory of uniaxially anistotropic materials exhibiting opposite signs of permittivity or permeability along and orthogonal the axis of anisotropy. HMs host a wide spatial spectrum of propagating waves, i.e., high gradient field features can be transferred in HMs owing to the propagating waves in ideally indefinitely large spatial spectrum. Optical HMs are mainly constructed by periodic alternating layers of plasmonic metals and dielectrics. The power emitted by point sources (and arrays of point sources) in the vicinity of HMs is highly boosted compared to regular dielectric media. Moreover, most of the power is absorbed by the HM. Similar characteristics can be realized using graphene layers instead of metals in the infrared regime, where the chemical potential can be an effective means of controlling emission enhancement. Thereafter, a reactively loaded transmission line grid is presented as an example of a two-dimensional HMs, where the canalization of large spectral waves leads to transferring high resolution features. HMs can also be molded into resonators that provide high-quality resonances even in subwavelength dimensions. These extraordinary resonances are demonstrated to boost radiative emission of dipolar emissions. Another exotic property of anisotropic metamaterials is investigated with near-zero permittivity conditions where huge electric field enhancements are achieved in larger intensities than those demonstrated using isotropic near-zero permittivity materials. Lastly, a circular cluster of plasmonic nanospheres under azimuthally polarized vector beams are studied as a way of boosting local magnetic field and isolating it from electric field, which is promising for studying weak magnetic transitions in high frequency range.