Highly Efficient Broadband Light Absorber Based on Nonuniform Hyperbolic Metamaterial Film

Nina A Zharova,Alexander A Zharov,Alexander A Zharov

doi:10.1155/2018/4578148

Abstract

We develop a concept of highly efficient broadband light absorber based on nonuniform hyperbolic metamaterial. We suggest a gradual bending of the anisotropy axis inside the metamaterial that results in spatial shift of the area of resonant absorption depending on the incidence angle. In this resonant region the wavevector of light is parallel to the generatrix of resonant cone and the radiation losses are maximal because of extremely high value of refraction index. Changing the radiation frequency also shifts the spatial position of the resonant region so that high level of absorption may be achieved in wide frequency range. Using the model of nanowire medium (silver wires in silica host) we predict that 200 nm film of this hyperbolic metamaterial allows reaching almost total absorption of radiation throughout the visible band.

Highlights

Exotic and interesting electromagnetic properties of the socalled hyperbolic metamaterials (HMs) cause their extensive study [1,2,3,4,5,6,7]
The ability to support high-index volume electromagnetic modes is one of the main advantages of HM, and it results from the subwavelength light localization, which is a characteristic feature of surface plasmon polaritons
The similarity comes from the fact that the volume electromagnetic mode in HM is the superposition of interacting plasmon modes localized at the nearby metal-dielectric interfaces

Summary

Introduction

Exotic and interesting electromagnetic properties of the socalled hyperbolic metamaterials (HMs) cause their extensive study [1,2,3,4,5,6,7]. An interesting approach for increasing the absorption in hyperbolic media was proposed in [27] where the authors experimentally observed strongly reduced reflection from roughened metamaterial surface Another approach for increasing the absorption is to turn the optical axis of HM in such a way that the direction of the resonance cone generatrix would coincide with the normal to the HM interface [5,6,7]. In this case normally incident light directly transforms into small-scale radiation; rather high reflection takes place (see Figure 4) which has a detrimental effect on the absorptivity of the HM layer. The absorption can be increased due to the medium inhomogeneity

Statement of the Problem

Reflection from Homogeneous HM Slab

Nonuniform Absorber

Conclusion