CAREER: Light Manipulation in Metal-Dielectric Multilayer Metamaterials with Large Anisotropy

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Nontechnical Description: Metamaterials are artificially structured composite materials with properties significantly different from those of the natural materials. The permittivity of an optical material is an important measure of its ability to store electromagnetic energy and to convert electromagnetic energy into heat. The permittivities of the most common optical materials are usually isotropic (i.e., the same value in all directions), with positive values for dielectric or transparent materials such as glass and water. By placing dielectric and metallic thin layers in alternative order, new types of optical metamaterials, namely metal-dielectric multilayer metamaterials, are created with permittivities that could not be realized using natural materials: with permittivity values designed to be very large, or very small, and different in different directions of the materials. In this research multilayer metamaterials are utilized to study novel phenomena of light propagation and manipulation and to address current challenges in optical metamaterials. This research paves the way for advances of multilayer metamaterial-based applications in optical communications, imaging processing, sensing, solar energy harvesting and adaptive optics. The research effort is integrated with education and outreach activities, including training students in metamaterials, development of optics learning modules in undergraduate and graduate courses, and organizing a nanotechnology workshop for public audiences, including K-12 students.Technical Description: The goals of the research component of this CAREER award are to study extraordinary light manipulation using metal-dielectric multilayer metamaterials with large anisotropy, including epsilon-near-zero, hyperbolic, and epsilon-very-large metamaterials, and to explore new optical physics phenomena using these metamaterials. Combined approaches of theoretical analysis, numerical simulation, materials fabrication and experimental characterization are used in the research to gain fundamental understanding of light-matter interactions in multilayer metamaterials. The research includes the following components: (i) accurate determination of the effective permittivity of metamaterials by probing the reflectance and transmittance, in both amplitude and phase, via an advanced optical vortex spectroscopic technique; (ii) exploring optical nonlocalities in periodic and quasiperiodic multilayer metamaterials for realization of Dirac physics via Zitterbewegung and Klein tunneling effects; (iii) design of patterned multilayer hyperbolic metamaterials for the generation of complex optical vector vortex beams to explore structured light manipulation; and (iv) verification of a novel concept of loss-anisotropic metamaterials, to demonstrate counterintuitive phenomena of absorption loss induced transmission and beam propagation.