Bulk Metamaterials Exhibiting Chemically Tunable Hyperbolic Responses

Abstract

Extraordinary properties of traditional hyperbolic metamaterials, not found in nature, arise from their man-made subwavelength structures causing unique light−matter interactions. However, their preparation requiring nanofabrication processes is highly challenging and merely provides nanoscale two-dimensional structures. Stabilizing their bulk forms via scalable procedures has been a sought-goal for broad applications of this technology. Herein, we report a new strategy of designing and realizing bulk metamaterials with finely tunable hyperbolic responses. We develop a facile two-step process: (1) self-assembly to obtain heterostructured nanohybrids of building blocks and (2) consolidation to convert nanohybrid powders to dense bulk pellets. Our samples have centimeter-scale dimensions typically, readily further scalable. Importantly, the thickness of building blocks and their relative concentration in bulk materials serve as a delicate means of controlling hyperbolic responses. The resulting new bulk heterostructured material system consists of the alternating h-BN and graphite/graphene nanolayers and exhibits significant modulation in both type-I and type-II hyperbolic resonance modes. It is the first example of real bulk hyperbolic metamaterials, consequently displaying the capability of tuning their responses along both in-plane and out-of-plane directions of the materials for the first time. It also distinctly interacts with unpolarized and polarized transverse magnetic and electronic beams to give unique hyperbolic responses. Our achievement can be a new platform to create various bulk metamaterials without complicated nanofabrication techniques. Our facile synthesis method using common laboratory techniques can open doors to broad-range researchers for active interdisciplinary studies for this otherwise hardly accessible technology.

A planar ultraviolet objective lens for optical axis free imaging nanolithography by employing optical negative refraction

“…1(b), the conditions of ε xx = ε yy > 0 and ε zz < 0 should be satisfied, which means that the HMM supporting optical negative refraction should belong to type-I. 23,24 Hence, the structural parameters of the multilayer structure need to fulfil this requirement of − ε m / ε d < t m / t d < − ε d / ε m (the imaginary parts of ε m and ε d are ignored here). For the parameters of the multilayer structure in this paper, ε xx = ε yy = 3.0985 + 0.3370 i and ε zz = −8.6019 + 2.3818 i .…”

Hyperbolic metamaterials: fusing artificial structures to natural 2D materials

“…Recently, various designs other than the multilayer and nanowire structures are proposed such as 3D nanorod arrays [127], core-shell nanoparticles [269,270], hyperbolic van der Waals crystals [271], and films of carbon nanotubes [272]. In addition, metasurface studies have included many attempts to achieve the large-area processing of HMMs using nanomanufacturing methods such as nanoimprinting, colloidal lithography, aerosol jets parallel printing, and spark plasma sintering [273][274][275][276]. If successful, these methods could substantially accelerate the use and development of HMMs for practical application in photonic devices.…”

Electrically tunable metasurfaces: from direct to indirect mechanisms

“…The various mechanisms introduced so far anticipate to pave the way for developments of new science and practical applications. The development of spatiotemporal metasurfaces based on novel materials and dynamic optical devices would lead to physical phenomena such as non-Hermitian systems [91][92][93] and topological photonic systems [94][95][96][97][98][99][100] and arguably derive fascinating ideas for further advanced electro-optical devices [98,[101][102][103]. Additionally, electrically operated nanophotonic devices can be easily extended to industrial uses.…”