Optical absorption of hyperbolic metamaterial with stochastic surfaces.

Jingjing Liu,Alexandra Boltasseva,Gururaj V Naik,Vladimir M Shalaev,Clayton Devault,Satoshi Ishii,Evgenii Narimanov

doi:10.1364/oe.22.008893

Abstract

We investigate the absorption properties of planar hyperbolic metamaterials (HMMs) consisting of metal-dielectric multilayers, which support propagating plane waves with anomalously large wavevectors and high photonic-density-of-states over a broad bandwidth. An interface formed by depositing indium-tin-oxide nanoparticles on an HMM surface scatters light into the high-k propagating modes of the metamaterial and reduces reflection. We compare the reflection and absorption from an HMM with the nanoparticle cover layer versus those of a metal film with the same thickness also covered with the nanoparticles. It is predicted that the super absorption properties of HMM show up when exceedingly large amounts of high-k modes are excited by strong plasmonic resonances. In the case that the coupling interface is formed by non-resonance scatterers, there is almost the same enhancement in the absorption of stochastically perturbed HMM compared to that of metal.

Highlights

Metamaterials are artificially engineered structures with subwavelength features whose optical properties transcend those found in nature
We investigate the absorption properties of planar hyperbolic metamaterials (HMMs) consisting of metal-dielectric multilayers, which support propagating plane waves with anomalously large wavevectors and high photonic-density-of-states over a broad bandwidth
It is predicted that the super absorption properties of HMM show up when exceedingly large amounts of high-k modes are excited by strong plasmonic resonances

Summary

Introduction

Metamaterials are artificially engineered structures with subwavelength features whose optical properties transcend those found in nature. The two most common structures used to realize an HMM are metallic nanowires embedded in a dielectric matrix [6,7,8] and periodic planar metal-dielectric layers [9,10,11,12] These uniaxial media with the elements of the permittivity tensor ε = diag(ε⊥ ,ε ,ε ) being parallel ( ε ) and perpendicular ( ε⊥ ) to the sample surface are highly anisotropic and exhibit hyperbolic dispersion as ε⊥ and ε are simultaneously of opposite sign. The decay routes introduced by the scattering events implement the energy transfer from the stochastic surface to the subsequent metal film. A detailed study of controlling the reflection and absorption by stochastic surfaces formed on HMMs and metal films is presented and possible mechanisms are discussed. We use epitaxially grown titanium nitride (TiN), aluminum scandium nitride ((Al,Sc)N) superlattice to form HMMs, and the stochastic surface is introduced by indium-tin-oxide (ITO) nanoparticles

Experiment

Discussion

Conclusion