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Artificial Metamaterials, Metasurfaces, and Their Applications
Published in Song Sun, Wei Tan, Su-Huai Wei, Emergent Micro- and Nanomaterials for Optical, Infrared, and Terahertz Applications, 2023
Modern advanced optical devices and systems operating from visible to infrared, terahertz, and millimeter wave, are derived from naturally available bulk material, such as metals, dielectrics, plastics, and ceramic. Despite the excellent performances of these bulk materials in electromagnetic wave control, they are either obtained from natural environment or synthesized through excessive experiments with tedious trial-and-error process. More importantly, the inherent properties of these bulk materials (e.g., positive refractive index) constrain the scientists and technicians to design and realize exotic electromagnetic responses (e.g., invisible cloaking). Hence, a long-standing dream for researchers is to develop an artificial means to define the properties of materials at will and control the electromagnetic waves flexibly and precisely. Such fabulously scientific fantasy motivates the birth of meta-materials. The prefix meta is a Greek word with the meaning of beyond, indicating metamaterials with exotic characteristics that have not been seen in natural materials. Metamaterials are normally composed by unique subwavelength micro- and nano-structures, in which the interactions between light and these man-made structures, rather than the intrinsically chemical composition, give rise to the desired properties. As a result, metamaterials shed light on artificial control of electromagnetic waves in a pre-designed manner, which can hardly be achieved with conventional bulk materials.
Tunable Metamaterials
Published in Pankaj K. Choudhury, Metamaterials, 2021
Metamaterial is a kind of artificial structure or material with exotic physical properties that natural materials do not possess. The electromagnetic parameters can be controlled by artificial structures, which provide a way to control the electromagnetic waves [1–5]. Metamaterial design has a large degree of freedom. It can work in different frequency ranges by properly designing the structural parameters. Therefore, metamaterials have a wide application prospect in the fields of radio frequency (including absorbing material, antenna, etc.), terahertz (THz; including THz sensor, detector, etc.) and optics (including perfect lens, invisible cloak, super-resolution imaging, etc.). The electromagnetic properties of metamaterials are realized by the electromagnetic responses of specific structures. However, the fixed structure of metamaterial results in a specific range of operation frequency. Beyond this range, the exotic electromagnetic properties will be reduced or even disappear. This phenomenon means that once the operating frequency is changed, it is necessary to redesign the metamaterial structure to achieve the same property, thus limiting its practicability. Obviously, the practicality of metamaterials will be greatly increased if the properties of metamaterials can be controlled by changing the external field without changing the structure.
Cloaking and Transformation Media
Published in Filippo Capolino, Applications of Metamaterials, 2017
Ulf Leonhardt, Thomas G. Philbin
Metamaterials are materials with electromagnetic properties that originate from human-made subwavelength structures [6–8]. Perhaps the best-known metamaterials are the materials used in the pioneering demonstrations of negative refraction [16] or invisibility cloaking [11] of microwaves (Figure 6.1), or for negative refraction of near-visible light [17]. These materials consist of metallic cells that are smaller than the relevant electromagnetic wavelength. Each cell acts like an artificial atom that can be tuned by changing the shape and the dimensions of the metallic structure. Metamaterials have a long history: the ancient Romans invented ruby glass, which is a metamaterial, although the Romans presumably did not know this concept. Ruby glass [18] contains nanoscale gold colloids that render the glass neither golden nor transparent, but ruby, depending on the size and concentration of the gold droplets. The color originates from a resonance of the surface plasmons [19] on the metallic droplets. Metamaterials per se are nothing new: what is new is the degree of control over the structures in the material that generate the desired properties.
Nondestructive testing algorithm of building concrete material defects based on machine learning
Published in Journal of Control and Decision, 2023
The rule is often used in ray tracing to calculate degrees of incident or refract, and in empirical optics to determine an object’s index of refraction. Metamaterials, that allow light to just be bending backwards at a negative index of refraction with a negative refractive index, also satisfy the principle. The ray-tracing approach has an impact on tomography quality and dependability. The Snell’s law is used to enhance the ray tracing technique’s reliability, and the disruption of the locations is taken into account such that the Snell’s law can alter the beam more efficiently. Fibre optics is a major application of Snell's Law. Optical fibre is utilised in a variety of industries, ranging from communications to elevated data transfer in computing. The illumination must be steered along the centre of the structure because the fibres really are not spread out in flat surfaces (Zhuang et al., 2020). The ray tracing of Snell theorem is not to directly calculate the wave formula, but to calculate the ray path on both sides of the interface between two kinds of media. To realise the demand of Snell theorem, we need to randomly select three continuous points in the medium path, and then calculate the refraction theorem between the points (Luo et al., 2019). When light flows through a rapid medium and into a slow media, it curves towards its corresponding to the boundary between two different media. Let us put the derivatives of rate with respect to variable equal to zero to reduce the time. We also employ the sine concept of contrary direction over hypotenuse to connect lengths to incident and reflections degrees.
A highly efficient deca-band metasurface absorber for diverse microwave applications
Published in Waves in Random and Complex Media, 2022
Adnan Yousaf, Abdul Wakeel, Zeeshan Zahid, Mudassir Murtaza, Adil Masood Siddiqui, Muhammad Imran
Metamaterials exhibit exotic properties such as negative permittivity (), negative permeability (), and refractive index. In 2D metasurfaces, these properties are achieved using an amalgamation of dielectric materials with metals [1]. An eminent class of metasurfaces, i.e. metasurface absorbers (MA) has been utilized in vast applications, e.g. energy harvesting [2], RCS reduction [3], and absorbing undesired frequencies in secure arenas. Metamaterial absorbers have been realized in various forms, i.e. passive elements-based [4–7], active elements-based [8,9], and multi-functional nanostructures [10–13]. The broadband MA presented in the literature provides absorptions over a large band without providing the flexibility of transmitting a specific band. On the other hand, multiband MA provides absorption peaks at selected frequencies [14–25]. However, the existing multiband MA possesses relatively fewer absorption peaks with angular stability up to 45˚ to 60˚ and polarization sensitivity.
Analytical relationships for yield stress of five mechanical meta-biomaterials
Published in Mechanics Based Design of Structures and Machines, 2022
N. Ghavidelnia, S. Jedari Salami, R. Hedayati
Mechanical metamaterials and designer lattice structures are artificial materials with repeated regular microstructures which gain their effective mechanical properties mostly from the underlying micro-architectures, rather than the composition of the bulk material they are made of (Yu et al. 2018). Mechanical metamaterials and designer lattice structures have been developed for unprecedented properties such as negative bulk modulus (Ding et al. 2007; Fang et al. 2006), negative Poisson’s ratio (Babaee et al. 2013; Dudek, Gatt, and Grima 2020; Hedayati, Mirzaali, et al. 2018; Patiballa and Krishnan 2020), negative effective mass (Huang, Sun, and Huang 2009; Yang et al. 2008), and arbitrary stiffness matrices (also known as pentamodes (Bückmann et al. 2014; Hedayati, Leeflang, and Zadpoor 2017; Hedayati, Salami, et al. 2019; Kadic et al. 2012)). Due to such exotic characteristics, mechanical metamaterials have a variety of applications, for example, in energy storage, biomedical and bioengineering applications, acoustics, photonics, thermal management, and high energy absorption (Chen and Karpov 2014; Florijn, Coulais, and van Hecke 2014; Hedayati, Hosseini-Toudeshky, et al. 2018; Hedayati, Sadighi, et al. 2018; Kolken et al. 2018; Li and Wang 2015; Silverberg et al. 2014). As the application of mechanical metamaterials has become more prevalent in scientific and industrial fields, researchers have focused their interest in studying the mechanical properties of mechanical metamaterials (Lee, Singer, and Thomas 2012).