Microscopic Interference Full‐Color Printing Using Grayscale‐Patterned Fabry–Perot Resonance Cavities

absorption of light. It is, however, possible to engineer artificial materials that are extremely thin and can absorb nearly 100% of the incident light. The most common approach to achieving near perfect absorption (NPA) of light consists of "blocking" the possibility of transmission by, for example, using a reflective surface. Under these circumstances, the amount of light absorbed is controlled by the reflectance of the material, since, in these cases, the absorption is given by A = 1 − | r | 2 . Clearly, high absorption can be obtained when there is vanishing reflectance (r = 0), which takes place under conditions of optical impedance matching. [4] In the following section, we discuss physical interpretations and mechanisms that have been employed for achieving near complete absorption of light using metallic nanostructures, including metasurfaces, as the absorptive element. This is followed by an overview of the applications of near-perfect absorption in fields such as chemical sensing, optoelectronics and photocatalysis. This review ends with an outlook. We note that near-perfect absorption can be achieved with a wide range of materials, for which excellent review papers have been previously published. [5][6][7] The Physics of Perfect Absorption Thin Film Perfect Absorbers: InterferenceAs an introduction, we first review simple thin film approaches to NPA since these play a fundamental role in understanding the underlying physics. Optical thin-film coatings are essential in optical systems today and the simplest example of a thin-film absorber consists of a stack of an optically thin metal film, a thin dielectric film and a highly reflective metallic film. Thin film coatings are widely used as anti-and high-reflection coatings, beamsplitters, and wavelength filters on lenses, windows, displays, [8] and absorbers for efficiency enhancements in photovoltaic cells, [9] as well light emitting diodes (LED) and photodetectors. [10] Their characteristics, design, and fabrication have been studied for over a century and are well-known. [4] In the next section, we will further discuss thin film absorbers where one layer is textured on the nanoscale, but thin-film systems are particularly useful as optical absorbers exhibiting distinct advantages over nanostructured optical metasurfaces. While textured surfaces require an additional level of processing, potentially requiring complex, top-down nanofabrication techniques, [11][12][13] Near-complete absorption of light has the potential to underpin advances in photodetection, advanced chemistry, coloration of materials, and energy. This review paper reports recent progress on the development of metasurfaces and thin film structures that produce strong absorption bands in the visible and longer wavelength regions of the electromagnetic spectrum, due in part to the excitation of plasmonic resonances. Proof-of-concept demonstrations are discussed for applications of these in chemical sensing, the generation of structural color, the creation of optoelectronic devices, and p...

Section: Applicationsmentioning

confidence: 99%

Plasmonic Near‐Complete Optical Absorption and Its Applications

Wesemann

Panchenko

et al. 2019

“…Plasmonic nanostructures have generated much interest with the development of recent nanofabrication methods, due to capability of optical field localizations into subwavelength dimensions. The plasmonic nanostructures have also shown great promise for the structural colors . The early demonstration of extraordinary optical transmissions through a hole array periodically perforated on a thin metal film can be considered as the first example .…”

Section: Structural Color Filtersmentioning

confidence: 99%

Engineering Light at the Nanoscale: Structural Color Filters and Broadband Perfect Absorbers

Lee

et al. 2017

168

121

Recent advances in fabrication and processing methods have spurred many breakthroughs in the field of nanostructures that provide novel ways of manipulating light interaction on a well controllable manner, thereby enabling a wide variety of innovative applications. Structural colors have shown great promise as an alternative for existing colorant‐based filters due to their noticeable advantages, which open up diverse potential applications such as energy‐efficient displays, ultrahigh‐resolution imaging, ultrahigh‐sensitivity biosensors, and building‐integrated photovoltaics. Broadband perfect absorbers, which exploit extraordinary optical phenomena at subwavelength scale, have also received increasing attention due to their capability of improving efficiency and performance characteristics of various applications including thermoelectrics, invisibility, solar‐thermal‐energy harvesting, and imaging. This review highlights some recent progress in these two related fields. The structural colors based on optical resonances in thin‐film structures, guided‐mode resonances in slab waveguide gratings, and surface plasmon resonances in plasmonic nanoresonators are described. Representative achievements associated with the broadband perfect absorbers, which include schemes employing highly absorbing media, multi‐cavity resonances, and broadband impedance matching are investigated.

“…Metasurfaces, which indicate planar distribution of periodic or semiperiodic subwavelength scale structures, have been studied in various optical fields thanks to their unprecedented ability to control light properties. The ability to modulate electromagnetic characteristics in subwavelength scale, especially optical phase or amplitude, insure that metasurfaces are suitable for various applications such as hologram generation, anomalous beam refraction, color generation, and orbital angular momentum generation . They are also being studied for versatile functionalities as a means of replacing bulk optical components such as lens, waveplates, polarizers, diffuser, and retroreflector .…”

Section: Introductionmentioning

confidence: 99%

Single‐Layer Bifacial Metasurface: Full‐Space Visible Light Control

Sung

Lee

Choi

et al. 2019

expansion order. Based on this parity, zero backward scattering is achievable under the condition that electric permittivity and magnetic permeability of the scattering body are equal to each other. [1] This effect is dubbed as Kerker effect, known to be due to destructive interference of the electric and magnetic mode radiation in the reflection space, which stems from various expansion orders of Mie scattering coefficients. [2][3][4][5] Metasurfaces, which indicate planar distribution of periodic or semiperiodic subwavelength scale structures, have been studied in various optical fields thanks to their unprecedented ability to control light properties. The ability to modulate electromagnetic characteristics in subwavelength scale, especially optical phase or amplitude, insure that metasurfaces are suitable for various applications such as hologram generation, [6,7] anomalous beam refraction, [8,9] color generation, [10,11] and orbital angular momentum generation. [12] They are also being studied for versatile functionalities as a means of replacing bulk optical components such as lens, [13,14] waveplates, [15] polarizers, [16,17] diffuser, [18] and retroreflector. [19] Recently, thanks to widespread attention of metamaterials in nanophotonics, the scattering radiation patterns including abovementioned multipolar phase effects are utilized for various optical or physical applications. [3,5,[20][21][22][23] For extended functionalities with respect to radiating pattern and corresponding efficiency to desired direction, generalized Kerker effect is exerting its influence as one of the important methods in the field of metaoptics. For instance, by overlapping ED and MD mode with identical value, Huygens' metasurface is proposed to suppress backward radiation, leading to high transmission efficiency. [24] Further interference of multipole mode radiations also enables directive radiation to reflection space, such as perfect magnetic mirrors as well. [25] By fine-tuning of the phase and amplitude ratio of each multipole mode, polarization-control metasurface, high-order diffraction control, and even directive dispersive device have been implemented so far. [26][27][28] Previously, full-space control has been studied as one of the significant metasurface researches; transmission-reflection integrated bifunctional and trifunctional metasurfaces were demonstrated by multilayered structure which operates in gigahertz range. [29,30] However, this more-than-one function device demands additional degrees of freedom in terms of design, so that the meta-atom should have large dimensions as well as Optical metasurfaces have attracted considerable attention thanks to their unprecedented ability to control the electromagnetic properties of light in subwavelength scale. These metasurface-integrated devices not only have the merit of compact form factor but also exhibit some better performance in comparison with conventional bulk optic devices. In this work, a novel metasurface that enables full-space light control is realized, off...