Strong absorption and selective thermal emission from a midinfrared metamaterial

Abstract

We demonstrate thin-film metamaterials with resonances in the mid-infrared wavelength range. Our structures are numerically modeled and experimentally characterized by reflection and angularly-resolved thermal emission spectroscopy. We demonstrate strong and controllable absorption resonances across the mid-infrared wavelength range. In addition, the polarized thermal emission from these samples is shown to be highly selective and largely independent of emission angles from normal to 45 degrees. Experimental results are compared to numerical models with excellent agreement. Such structures hold promise for large-area, low-cost metamaterial coatings for control of gray-or black-body thermal signatures, as well as for possible mid-IR sensing applications.

Compact photonic-crystal superabsorbers from strongly absorbing media

“…[8][9][10] This vast applications potential has spurred intensive research efforts for new efficient absorber designs across the electromagnetic (EM) spectrum. Traditional architectures may involve a top anti-reflection coating 3 to enhance the in-coupling of light and a backreflector that facilitates a second light pass.…”

“…2 Many current works go beyond the latter approach with focused efforts around absorption optimization by nano/micro-structuring the absorber and/or its environment, [14][15][16][17] including structures aiming for plasmon-mediated near-field enhancement in the vicinity of the absorber. 4,5,8,9,11,18 Photonic-crystals (PCs) have been researched for absorption control both as back-reflector components [19][20][21] and directly as the absorptive medium. [22][23][24][25][26] The latter cases seem promising schemes for one-step absorption platforms where the lossy photonic crystal could facilitate the incoupling of all impinging light and at the same time would mold the coupled mode in a fashion that enables all light to get absorbed.…”

Dual-Band Coherent Perfect Absorption/Thermal

“…On the other hand, the ability of controlling emission spectrum and direction also has important applications such as tailoring radiation [6,7] and thermal sensing. To increase coherence and modify emission characteristics, there has been increasing attention on patterning surface microstructures, such as subwavelength gratings [8]- [11], microcavities [12]- [15], and metamaterials [16]- [19]. It is of great interest in manipulating light to achieve total absorption at a subwavelength scale.…”

Light concentration using hetero-junctions of anisotropic low permittivity metamaterials

“…For instance, MTMs show superior performance over prior techniques for absorption, wave guidance and narrowband emission of light for solar and/or thermal photovoltaic cell applications. Recently, various works have used metamaterials for the design of thermal absorbers [15][16][17][18][19][20] and selective thermal emitters [21][22][23][24][25][26] potentially for thermal photovoltaics (TPV), as well as Solar-TPV systems. 27,28 A certain class of metamaterials have permittivity values close to zero which are also known as epsilon near zero (ENZ) materials in the literature.…”