A multiband perfect absorber based on hyperbolic metamaterials.

Kandammathe Valiyaveedu Sreekanth,Yunus Alapan,Mohamed Elkabbash,Umut A Gurkan,Alireza R Rashed,Giuseppe Strangi

doi:10.1038/srep26272

Kandammathe Valiyaveedu Sreekanth, Yunus Alapan + Show 4 more

Open Access

https://doi.org/10.1038/srep26272

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Abstract

In recent years, considerable research efforts have been focused on near-perfect and perfect light absorption using metamaterials spanning frequency ranges from microwaves to visible frequencies. This relatively young field is currently facing many challenges that hampers its possible practical applications. In this paper, we present grating coupled-hyperbolic metamaterials (GC-HMM) as multiband perfect absorber that can offer extremely high flexibility in engineering the properties of electromagnetic absorption. The fabricated GC-HMMs exhibit several highly desirable features for technological applications such as polarization independence, wide angle range, broad- and narrow- band modes, multiband perfect and near perfect absorption in the visible to near-IR and mid-IR spectral range. In addition, we report a direct application of the presented system as an absorption based plasmonic sensor with a record figure of merit for this class of sensors.

Highlights

Derived real parts of effective uniaxial permittivity components of (b) Au-Al2O3 HMM, and (c) Ag-TiO2 HMM
We have previously investigated the existence of such bulk plasmon polaritons (BPPs) in our grating coupled HMM (GC-HMM) system[29,30] and the spontaneous emission rate enhancement of fluorescent molecules embedded GC-HMM, which experimentally prove the existence of high photonic density of states[31]
All four modes are blue shifted differently with increase in angles of incidence. This blue shift is attributed to the variation in modal index of BPP modes with incident angle

Summary

Introduction

Derived real parts of effective uniaxial permittivity components of (b) Au-Al2O3 HMM, and (c) Ag-TiO2 HMM. HMMs have been theoretically predicted as electromagnetic absorbers for scattered fields This was experimentally demonstrated by placing scatterers on top of HMM, showing enhanced absorption but it was neither perfect nor narrow-band absorption[22,23,24]. HMMs are designed by interlocking low loss dielectric materials and highly reflective noble metals, the strong absorption of light is realized via the indefinite dispersion of such meta-structures. This unusual hyperbolic dispersion results in a divergence of the photonic density of states, and it leads to a dramatic increase in the absorption of incident photons that get absorbed into the propagating modes of the hyperbolic medium. We report on how our ultra-narrow band absorber can be used to realize a high-sensitivity absorption-based plasmonic sensor with an unprecedented high figure of merit

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