Abstract
The rapid advent of radio-frequency (RF) and microwave technologies and systems have given rise to serious electromagnetic pollution, interference and jamming for high-precision detection devices, and even threats to human health. To mitigate these negative impacts, electromagnetic interference (EMI) shielding materials and structures have been widely deployed to isolate sophisticated instruments or human settlements from potential EMI sources growing every day. We discuss recent advances in lightweight, low-profile electromagnetic absorbing media, such as metamaterials, metasurfaces, and nanomaterial-based solutions, which may provide a relatively easy solution for EMI shielding and suppressing unwanted RF and microwave noises. We present a general review of the recent progress on theories, designs, modeling techniques, fabrication, and performance comparison for these emerging EMI and electromagnetic compatibility (EMC) media.
Keywords
- EMI
- EMC
- metamaterials
- metasurfaces
- perfect electromagnetic absorbers
1. Introduction
Electromagnetic absorbers have important applications in a plethora of applications, including but not limited to electromagnetic interferences and electromagnetic compatibility [1, 2, 3, 4, 5], stealth [6, 7, 8, 9], camouflage [10], shielding [11, 12, 13], energy harvesting [14, 15], as well as antenna and optical measurements [2, 16, 17, 18]. Recently, the scientific interest has focused on EMC and EMI shielding that studies how to suppress noise or interference in various electronic appliances and radiative damage to humans caused by unintended EM signals. In these applications, electromagnetic absorbers play an essential role. As one of the representative examples, a high-performance and cost-effective anechoic chamber, which can provide a zero-reflection environment mimicking free space, is of paramount importance for EMC test, antenna, and scattering measurements, among many other applications. As illustrated in Figure 1(a), in an anechoic chamber, the entire inner surfaces (walls, ceiling, and floor) are properly covered with absorbers to absorb waves propagating toward them and thus eliminate multipath interferences. Hence, a simple and well-defined propagation channel can be obtained between the transmitting source and receiving antennas or a scattering object for radar cross-section (RCS) measurements. Nearly perfect absorption, realized with an ultrathin, lightweight, and low-cost manner, makes the artificial surfaces and media (i.e., metamaterials and metasurfaces) advantageous over the conventional electromagnetic absorbers made of natural materials. Ever since the first perfect metamaterial absorber was proposed by Landy
The applications include RCS reduction and stealth [29], EMI shielding [12, 13], sensing [30, 31, 32, 33], terahertz imaging [34, 35, 36], energy harvesting, etc. A representative modern application of metamaterial absorbers may be the enhanced isolation in the multiple-input-multiple-output (MIMO) antenna system [37, 38], as depicted in Figure 1(b). With the growing demand for miniaturization of telecommunication devices, reducing the mutual coupling or cross-talk among the antenna elements has been a challenging task in MIMO systems. A specifically designed metamaterial absorber mostly consisting of periodic resonators can help improve the isolation among antenna elements and further enhance the efficiency of a MIMO system since it can significantly absorb the unwanted interferences among antennas.
The impedance of a material is defined as
In the same vein, although the intrinsic optical loss of metals is a major limitation in the performance of these devices, it is beneficial in improving light absorption. In 2008, Landy
2. Generalized theory for perfect electromagnetic absorbers
In this section, we will discuss the basic principles of extremely thin electromagnetic absorbers composed of an infinite two-dimensional array of electric dipoles, magnetic dipoles, or both. According to the optical theorem, when the scatterer interacts with the incident fields, the power depleted from the incident fields is the sum of the absorbed and scattered powers, i.e.,
where
Finally, the total incident power flowing through the surface
From Eqs. (1)-(3), the total extracted power (power extinction) is given by the cross-terms
The forward scattering sum rule is valid for any arbitrary absorbers, for which the scattered power
The absorbed power
Assuming that there are no grating sidelobes, the power extinction -
This can be seen as the optical theorem for infinite two-dimensional (2D) planar structures, such as metascreens or an ultrathin absorptive film. We know from Eqs. (5)-(7) that when the forward scattered power represents the total scattered power, i.e., no backward scattered (reflected) waves, the total absorption of the incident radiation can be achieved. In this case, the scattered power equals the absorbed power,
Consider an infinite 2D electric dipole array, separated from a PEC ground plane by a distance
where
where
For an arbitrary value
or from Eqs. (8), (9), and (12), we obtain the optimum (lossy and capacitive) surface impedance
When the distance between the array plane and the ground plane
In the following, we briefly discuss how to design and synthesize the grid array that provides the required surface impedance. It is instructive to study a metamaterial surface or metasurface formed by a 2D array of meta-atoms excited by an external electric field
where
where
where the area of the metasurface lattice S =
Under the lossless and low frequency condition, the polarizability is approximately given by
So, Eq. (17) can be further reduced to
For a subwavelength lattice, i.e.,
where
where
where
This can be achieved by tailoring the size, shape, and material property (i.e., dispersion of the complex permittivity) of the elementary inclusion (i.e., meta-atom) in the metasurface unit-cell. For a Salisbury-type absorber with
The first condition implies an individual scatterer is at its self-resonance, which considers the cancelation of a general sense, the maximum absorption cross-section of each inclusion in densely packed arrays
where
Figures 4 and 5 show metasurface absorbers based on 2D arrays of plasmonic disks [78] and electric ring resonators [79], respectively. It is clearly seen that the ultrathin and low-profile metasurface absorbers can significantly absorb the incident wave in the frequency band of interest. We note that these electric resonant inclusions can be equivalent to a 2D array of electric dipoles discussed above.
It is also possible to exploit a metasurface constituted by magnetic or magnetoelectric meta-atoms [9, 19, 22, 23] to build a perfect electromagnetic absorber. For example, Figure 2(c) and (d) consider a magnetic dipole array over a ground plane and the image. When a plane wave normally incident on the structure, the magnetic current density is induced:
and
where
The total averaged fields on the metasurface can be expressed as
where the surface impedances are given by
If the reader is interested in learning details about anisotropic magnetoelectric metasurfaces, please see Refs. [80, 81, 82].
Figure 6 shows an ultrathin electromagnetic absorber based on resonant magnetic structures. Under the excitation of a plane wave, a magnetic dipole array can be induced, and at resonance, the incident power can be absorbed, analogous to the function of the electric dipole array discussed above. The experimental results reported an absorption efficiency above 93% at 1.74 GHz at illumination angles up to 60 degrees [83]. Moreover, this absorber is 98% lighter than traditional microwave absorbers made of natural materials working at the same frequencies. As an alternative explanation, this structure can be seen as a metal-backed magnetic-near-zero (MNZ) metamaterial slab [84]. For an ultrathin metal-backed MNZ absorber, the permeability
On the contrary, if symmetric designs are considered (e.g., a suspended resistive film with optimal sheet impedance
3. Hyperbolic metamaterial absorbers
Hyperbolic metamaterials (HMMs) (see Figure 8) are known for their isofrequency contour and broadband singularity in the density of photonic states, which have led to many new photonic and optical applications, including the substrate for molding spontaneous emissions into a directional beam and the “rainbow trapping” structure for broadband light absorption [25, 86, 87, 88]. The effective medium theory can describe the effective permittivity of such an artificial anisotropic medium as:
where
Therefore, for an anisotropic medium with extreme material properties, i.e.,
Figure 9a considers a trenched HMM slab with a periodicity
where
and
Figure 9b shows the calculated dispersion diagram of a periodically trenched HMM slab constituted by stacked silver (Ag) and copper (Cu) thin-films with thickness tmetal, separated by 1 nm-thick niobium oxide (Nb2O5) insulating layers, of which the periodicity and air gap size are 300 nm and 150 nm, respectively. The realistic material properties extracted from experiments are used [89]. It can be seen from Figure 9b that near-zero group velocity can be achieved at certain wavelengths, resulting in the slow light effect and light trapping and absorption in the lossy (dissipative plasmon loss) and anisotropic HMM region. Figure 9c presents the associated contour plot of absorptance as a function of metal thickness
Additionally, the absorption spectrum can be readily tailored by varying the volume fraction of metal, which determines the permittivity tensor elements of HMM. Although a linear HMM-based absorber can exhibit a high and angle-independent optical absorption, its bandwidth is limited around the slow-wave modes. This limitation can be mitigated by exploiting a tapered-HMM, as shown in Figure 10a, which has been proposed to realize wideband photodetection and solar energy harvesting applications [88, 89, 90, 91]. Using tapered geometry, the bandwidth is expected to increase due to the superposition of multiple slow-wave modes. Figure 10b shows the contour plot of absorptance as a function of the photon energy and the angle of incidence. It is evidently seen that a broadband (1 eV to 1.6 eV) and wide-angle (0o to grazing angle) optical absorption can be obtained with the tapered HMM substrate backed by a metallic mirror (50 nm Ag thin-film). The capability to effectively trap photons over a wide range of photon energies and illumination angles is essential for building efficient hot-electron energy harvesters or photodetectors. Finally, we note that the general limitation on the maximum bandwidth of a ground-backed absorber should always obey the passivity and causality [93], following the physical bound
Similarly, an ultra-broadband HMM absorber can be realized in the RF and microwave regions by integrating two different-sized tapered HMM waveguides, as shown in Figure 11a [94], each of which has wide but different absorption bands, leading to a broadband slow-light response. By properly selecting the geometrical parameters for each waveguide in the HMM, multiple absorption bands can be achieved with different waveguides, as shown in Figure 11b. Such an approach can effectively widen the total absorption bandwidth. Experimental results in Ref. [94] validate the theoretical results, showing a very large absorption bandwidth ranging from 2.3 GHz to 40 GHz.
4. Future trends: reconfigurable absorbers based on plasmonic, graphene, and beyond
Electromagnetic wave absorbers are mainly utilized as boundary structures to prevent the scattering of electromagnetic fields. They can be divided into two main categories based on their operating bandwidth, i.e., resonant and broadband absorbers [95, 96]. Resonant absorbers typically depend on the designed material assemblies interrelating with the incident waves around certain resonance frequencies [96]. On the other hand, the wideband absorbers rely on material damping characteristics that are largely independent of electromagnetic frequencies and typically made of lossy dispersive materials [96]. Such broadband absorbing materials along with structural transition are commonly used in anechoic chambers to effectively emulate a non-reflecting unbounded medium suitable for testing radiating antenna elements [95]. Lately, there is an emphasis in the scientific community to design efficient plasmonic metamaterial-based absorbers. Light matter interaction in subwavelength metamaterial structures allowed various other applications including perfect lenses [45, 97], chiral surfaces [98, 99], transformational surfaces [100, 101], optical cloaking [100, 102, 103], spatial light switching [104, 105] and IR camouflage and microwave antennas because of certain useful characteristics [96]. In addition to these applications, the perfect metamaterial absorber (PMA) is designed as a tool to efficiently absorb electromagnetic waves utilizing plasmonic resonator elements embedded within its assembly.
Generally, metamaterial absorbers are composed of a patterned metal film over a continuous thin metallic film with a dielectric substrate sandwiched between them [96]. It should be noted that the definition of total absorptivity considers reflected electric field vector, i.e.,
The response of PMA is often described as an effective medium and characterized by properties such as complex electric permittivity (ε) and magnetic permeability (μ) [109]. Although much of the work on effective medium properties of metamaterials has been focused on the real part of ε and μ, as it contributes to negative refractive index properties, it is equally important to reduce losses represented by the imaginary part of ε and μ for practical applications related to wave propagation within negative refractive index medium [110, 111]. In contrast, the metamaterial absorbers rely on high material losses (large value of imaginary parts of ε and μ) and impedance matching with the background medium. Landy et al. provided the first experimental demonstration of near perfect metasurface absorption at GHz frequencies. The working principle of PMA relies on impedance matching between effective medium forming metasurface with dielectric and background medium to the free space background, rejecting the reflection and therefore efficiently absorbing the incident EM wave [19, 20]. Ever since, the design of PMAs has attracted significant attention ranging from microwave to optical frequencies [112, 113]. Apart from resonant absorption characteristics, the plasmonic effects also provide tremendous near field enhancement to improve the efficiency of solar cells [114], support for sensing [31], and enhanced thermal emission and photo-detection [115].
Recently, the electro-optic tunability of resonant absorption spectrum at THz frequencies is made possible by varying the frequency dependent conductivity of plasmonic materials through the use of graphene metasurface [22, 59]. The frequency dependent optical properties of graphene in the THz frequency range are controlled by its optoelectronic properties. The permittivity (
Here,
The surface conductivity of graphene (
Here,
The real-time tunability of Graphene Surface Plasmons (GSPs) is a distinct feature offered by graphene metasurface when compared to traditional noble metals. In addition, GSPs offer other benefits such as tighter mode volume confinement and lower intrinsic losses compared to conventional surface plasmon materials. The unique electro-optic tunability of graphene conductivity within the THz band makes it an attractive candidate for plasmonic metamaterial applications. Therefore, graphene enabled the research in surface plasmons to be redirected toward reconfigurable THz wave optics applications, including GSPP waveguides [116], modulators [24], THz cloaks [117], THz antennas [118], Fourier optics [119], photonic crystal nano-cavities [120], and biochemical sensors [31, 121]. The reconfigurable response of resonant absorption can offer additional functionalities, including wave modulation, polarization conversion, and sensing.
Here, we discuss a few selected applications of reconfigurable THz metasurface absorbers, as shown in Figure 13. Figure 13(a) shows graphene micro-ribbon metasurface design capable of efficiently absorbing THz radiation [22]. The chemical potential (
5. Conclusion
In this chapter, we have reviewed the most recent advances in the field of metamaterial and metasurface-based electromagnetic perfect absorbers. We have first provided a thorough theoretical investigation describing the material and geometrical conditions that may lead to a near-perfect absorption of light. Based on the well-known optical theorem, this analysis gives a power balance and clarifies the design process in the microwaves and terahertz. Next, we have discussed a peculiar and interesting class of perfect absorbers that are hyperbolic metamaterial absorbers. These devices exploit a particular dispersion of hyperbolic media and lead to robust and tunable absorbers. We finally have discussed the newly proposed graphene plasmonics based absorbers, which exploit the high conductivity and tunable optical properties of this 2D material to build some of the most appealing and versatile absorbers, with applications spanning energy harvesting, biosensing, or light polarization manipulation. This chapter can be helpful to theorists and experimentalists alike, working on the design of novel absorbers of light or even other types of waves.
References
- 1.
Mishra N, Kumari K, Chaudhary RK. An ultra-thin polarization independent quad-band microwave absorber-based on compact metamaterial structures for EMI/EMC applications. Int. J. Microw. Wireless Technol. 2018; 10 :422 - 2.
Holloway CL, DeLyser RR, German RF, McKenna P, Kanda M. Comparison of electromagnetic absorber used in anechoic and semi-anechoic chambers for emissions and immunity testing of digital devices. IEEE Transactions on Electromagnetic Compatibility. 1997; 39 :33 - 3.
Crawford ML, Workman JL, Thomas CL. Expanding the Bandwidth of TEM Cells for EMC Measurements. IEEE Transactions on Electromagnetic Compatibility. 1978; EMC-20 :368 - 4.
Groh C, Karst JP, Koch M, Garbe H. TEM waveguides for EMC measurements. IEEE Transactions on Electromagnetic Compatibility. 1999; 41 :440 - 5.
Mishra SR, Pavlasek TJF. Design of Absorber-Lined Chambers for EMC Measurements Using a Geometrical Optics Approach. IEEE Transactions on Electromagnetic Compatibility. 1984; EMC-26 :111 - 6.
L. Zhao, H. Liu, Z. He, and S. Dong, All-metal frequency-selective absorber/emitter for laser stealth and infrared stealth, Appl. Opt., AO 57 , 1757 (2018). - 7.
Panwar R, Puthucheri S, Singh D, Agarwala V. Design of Ferrite–Graphene-Based Thin Broadband Radar Wave Absorber for Stealth Application. IEEE Transactions on Magnetics. 2015; 51 :1 - 8.
Chakradhary VK, Baskey HB, Roshan R, Pathik A, Akhtar MJ. Design of Frequency Selective Surface-Based Hybrid Nanocomposite Absorber for Stealth Applications. IEEE Transactions on Microwave Theory and Techniques. 2018; 66 :4737 - 9.
Kim J, Han K, Hahn JW. Selective dual-band metamaterial perfect absorber for infrared stealth technology. Scientific Reports. 2017; 7 :6740 - 10.
Kim T, Bae J, Lee N, Cho HH. Hierarchical Metamaterials for Multispectral Camouflage of Infrared and Microwaves. Adv. Funct. Mater. 2019; 29 :1807319 - 11.
Sabah C, Dincer F, Karaaslan M, Unal E, Akgol O, Demirel E. Perfect metamaterial absorber with polarization and incident angle independencies based on ring and cross-wire resonators for shielding and a sensor application. Optics Communications. 2014; 322 :137 - 12.
Gholampoor M, Movassagh-Alanagh F, Salimkhani H. Fabrication of nano-Fe3O4 3D structure on carbon fibers as a microwave absorber and EMI shielding composite by modified EPD method. Solid State Sciences. 2017; 64 :51 - 13.
Micheli D, Apollo C, Pastore R, Bueno Morles R, Laurenzi S, Marchetti M. Nanostructured composite materials for electromagnetic interference shielding applications. Acta Astronautica. 2011; 69 :747 - 14.
Farhat M, Chen P-Y, Bagci H, Amra C, Guenneau S, Alù A. Thermal invisibility based on scattering cancellation and mantle cloaking. Scientific Reports. 2015; 5 :9876 - 15.
Dincer F. Electromagnetic energy harvesting application based on tunable perfect metamaterial absorber. Journal of Electromagnetic Waves and Applications. 2015; 29 :2444 - 16.
Chung BK, Chuah HT. Design and construction of a multipurpose wideband anechoic chamber. IEEE Antennas and Propagation Magazine. 2003; 45 :41 - 17.
S. F. Gregson, J. Dupuy, C. G. Parini, A. C. Newell, and G. E. Hindman, in 2011 Loughborough Antennas Propagation Conference (2011), pp. 1–4. - 18.
Qu Y, Li Q, Gong H, Du K, Bai S, Zhao D, et al. Spatially and Spectrally Resolved Narrowband Optical Absorber Based on 2D Grating Nanostructures on Metallic Films. Advanced Optical Materials. 2016; 4 :480 - 19.
Landy NI, Sajuyigbe S, Mock JJ, Smith DR, Padilla WJ. Perfect Metamaterial Absorber. Phys. Rev. Lett. 2008; 100 :207402 - 20.
Tao H, Landy NI, Bingham CM, Zhang X, Averitt RD, Padilla WJ. A metamaterial absorber for the terahertz regime: Design, fabrication and characterization, Opt. Express, OE. 2008; 16 (7181) - 21.
B.-Y. Wang, S.-B. Liu, B.-R. Bian, Z.-W. Mao, X.-C. Liu, B. Ma, and L. Chen, A novel ultrathin and broadband microwave metamaterial absorber, Journal of Applied Physics 116 , 094504 (2014). - 22.
Alaee R, Farhat M, Rockstuhl C, Lederer F. A perfect absorber made of a graphene micro-ribbon metamaterial, Opt. Express, OE. 2012; 20 (28017) - 23.
Cao T, Wei C, Simpson RE, Zhang L, Cryan MJ. Broadband Polarization-Independent Perfect Absorber Using a Phase-Change Metamaterial at Visible Frequencies. Scientific Reports. 2014; 4 :3955 - 24.
Zhang Y, Feng Y, Zhu B, Zhao J, Jiang T. Graphene based tunable metamaterial absorber and polarization modulation in terahertz frequency, Opt. Express, OE. 2014; 22 (22743) - 25.
Zhou J, Kaplan AF, Chen L, Guo LJ. Experiment and Theory of the Broadband Absorption by a Tapered Hyperbolic Metamaterial Array. ACS Photonics. 2014; 1 :618 - 26.
D. Chaurasiya, S. Ghosh, S. Bhattacharyya, and K. V. Srivastava, in 2014 IEEE International Microwave and RF Conference (IMaRC) (2014), pp. 96–99. - 27.
Singh AK, Abegaonkar MP, Koul SK. A Triple Band Polarization Insensitive Ultrathin Metamaterial Absorber for S- C- and X-Bands. Progress In Electromagnetics Research M. 2019; 77 :187 - 28.
W. Li, X. Zhou, Y. Ying, X. Qiao, F. Qin, Q. Li, and S. Che, Polarization-insensitive wide-angle multiband metamaterial absorber with a double-layer modified electric ring resonator array, AIP Advances 5 , 067151 (2015). - 29.
Liu T, Cao X, Gao J, Zheng Q, Li W, Yang H. RCS Reduction of Waveguide Slot Antenna With Metamaterial Absorber. IEEE Transactions on Antennas and Propagation. 2013; 61 :1479 - 30.
Luo S, Zhao J, Zuo D, Wang X. Perfect narrow band absorber for sensing applications, Opt. Express, OE. 2016; 24 (9288) - 31.
Amin M, Siddiqui O, Abutarboush H, Farhat M, Ramzan R. A THz graphene metasurface for polarization selective virus sensing. Carbon. 2021; 176 :580 - 32.
Liu N, Mesch M, Weiss T, Hentschel M, Giessen H. Infrared Perfect Absorber and Its Application As Plasmonic Sensor. Nano Lett. 2010; 10 :2342 - 33.
Zhang L, Farhat M, Salama KN. Spectrometer-Free Graphene Plasmonics Based Refractive Index Sensor. Sensors. 2020; 20 :2347 - 34.
Landy NI, Bingham CM, Tyler T, Jokerst N, Smith DR, Padilla WJ. Design, theory, and measurement of a polarization-insensitive absorber for terahertz imaging. Phys. Rev. B. 2009; 79 :125104 - 35.
Chen P-Y, Alù A. Subwavelength Imaging Using Phase-Conjugating Nonlinear Nanoantenna Arrays. Nano Lett. 2011; 11 :5514 - 36.
Wesemann L, Panchenko E, Singh K, Della Gaspera E, Gómez DE, Davis TJ, et al. Selective near-perfect absorbing mirror as a spatial frequency filter for optical image processing. APL Photonics. 2019; 4 :100801 - 37.
Sharawi MS, Numan AB, Khan MU, Aloi DN. A Dual-Element Dual-Band MIMO Antenna System With Enhanced Isolation for Mobile Terminals. IEEE Antennas and Wireless Propagation Letters. 2012; 11 :1006 - 38.
Zhang S, Ying Z, Xiong J, He S. Ultrawideband MIMO/Diversity Antennas With a Tree-Like Structure to Enhance Wideband Isolation. IEEE Antennas and Wireless Propagation Letters. 2009; 8 :1279 - 39.
Jackson JD. Classical Electrodynamics. 3rd ed. New York: Wiley; 1999 - 40.
Pendry JB, Holden AJ, Robbins DJ, Stewart WJ. Magnetism from conductors and enhanced nonlinear phenomena. IEEE Transactions on Microwave Theory and Techniques. 1999; 47 :2075 - 41.
D. M. Pozar, Microwave Engineering (John Wiley & Sons, 2011). - 42.
H. W. Ott, Electromagnetic Compatibility Engineering (John Wiley & Sons, 2011). - 43.
J. D. Baena, R. Marqués, F. Medina, and J. Martel, Artificial magnetic metamaterial design by using spiral resonators, Phys. Rev. B 69 , 014402 (2004). - 44.
Bilotti F, Toscano A, Vegni L, Aydin K, Alici KB, Ozbay E. Equivalent-Circuit Models for the Design of Metamaterials Based on Artificial Magnetic Inclusions. IEEE Transactions on Microwave Theory and Techniques. 2007; 55 :2865 - 45.
Pendry JB. Negative Refraction Makes a Perfect Lens. Phys. Rev. Lett. 2000; 85 :3966 - 46.
Shelby RA, Smith DR, Schultz S. Experimental Verification of a Negative Index of Refraction. Science. 2001; 292 :77 - 47.
Schurig D, Mock JJ, Justice BJ, Cummer SA, Pendry JB, Starr AF, et al. Metamaterial Electromagnetic Cloak at Microwave Frequencies. Science. 2006; 314 :977 - 48.
M. Farhat, P.-Y. Chen, S. Guenneau, and S. Enoch, Transformation Wave Physics: Electromagnetics, Elastodynamics, and Thermodynamics (CRC Press, 2016). - 49.
S. A. Maier, Plasmonics: Fundamentals and Applications (Springer Science & Business Media, 2007). - 50.
Brolo AG. Plasmonics for future biosensors. Nature Photonics. 2012; 6 :709 - 51.
Xiao S, Liu L, Qiu M. Resonator channel drop filters in a plasmon-polaritons metal, Opt. Express, OE. 2006; 14 (2932) - 52.
Liu Y, Cheng R, Liao L, Zhou H, Bai J, Liu G, et al. Plasmon resonance enhanced multicolour photodetection by graphene. Nature Communications. 2011; 2 :579 - 53.
Ma R-M, Oulton RF, Sorger VJ, Bartal G, Zhang X. Room-temperature sub-diffraction-limited plasmon laser by total internal reflection. Nature Materials. 2011; 10 :110 - 54.
C. Argyropoulos, P.-Y. Chen, G. D’Aguanno, N. Engheta, and A. Alù, Boosting optical nonlinearities in ε-near-zero plasmonic channels, Phys. Rev. B 85 , 045129 (2012). - 55.
Grosjean T, Mivelle M, Baida FI, Burr GW, Fischer UC. Diabolo Nanoantenna for Enhancing and Confining the Magnetic Optical Field. Nano Lett. 2011; 11 :1009 - 56.
Kildal P-S, Alfonso E, Valero-Nogueira A, Rajo-Iglesias E. Local Metamaterial-Based Waveguides in Gaps Between Parallel Metal Plates. IEEE Antennas and Wireless Propagation Letters. 2009; 8 :84 - 57.
Teperik TV, García de Abajo FJ, Borisov AG, Abdelsalam M, Bartlett PN, Sugawara Y, et al. Omnidirectional absorption in nanostructured metal surfaces. Nature Photonics. 2008; 2 :299 - 58.
Y. D. Chong, L. Ge, H. Cao, and A. D. Stone, Coherent Perfect Absorbers: Time-Reversed Lasers, Phys. Rev. Lett. 105 , 053901 (2010). - 59.
Amin M, Farhat M, Bağcı H. An ultra-broadband multilayered graphene absorber, Opt. Express, OE. 2013; 21 (29938) - 60.
Aalizadeh M, Khavasi A, Butun B, Ozbay E. Large-Area, Cost-Effective, Ultra-Broadband Perfect Absorber Utilizing Manganese in Metal-Insulator-Metal Structure. Scientific Reports. 2018; 8 :9162 - 61.
Rephaeli E, Fan S. Absorber and emitter for solar thermo-photovoltaic systems to achieve efficiency exceeding the Shockley-Queisser limit, Opt. Express, OE. 2009; 17 (15145) - 62.
M. Diem, T. Koschny, and C. M. Soukoulis, Wide-angle perfect absorber/thermal emitter in the terahertz regime, Phys. Rev. B 79 , 033101 (2009). - 63.
M. Kerker, The Scattering of Light and Other Electromagnetic Radiation: Physical Chemistry: A Series of Monographs (Academic Press, 2013). - 64.
Kwon D-H, Pozar DM. Optimal Characteristics of an Arbitrary Receive Antenna. IEEE Transactions on Antennas and Propagation. 2009; 57 :3720 - 65.
Fante RL, McCormack MT. Reflection properties of the Salisbury screen. IEEE Transactions on Antennas and Propagation. 1988; 36 :1443 - 66.
Chen P-Y, Argyropoulos C, D’Aguanno G, Alù A. Enhanced Second-Harmonic Generation by Metasurface Nanomixer and Nanocavity. ACS Photonics. 2015; 2 :1000 - 67.
A. Alù, First-principles homogenization theory for periodic metamaterials, Phys. Rev. B 84 , 075153 (2011). - 68.
S. Tretyakov, Analytical Modeling in Applied Electromagnetics (Artech House, 2003). - 69.
P. A. Belov and C. R. Simovski, Homogenization of electromagnetic crystals formed by uniaxial resonant scatterers, Phys. Rev. E 72 , 026615 (2005). - 70.
G. N. Watson, A Treatise on the Theory of Bessel Functions (Cambridge University Press, 1995). - 71.
M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables (U.S. Government Printing Office, 1964). - 72.
Simovski CR, Zouhdi S, Yatsenko VV. Electromagnetic interaction in dipole grids and prospective high-impedance surfaces. Radio Science. 2005; 40 :1 - 73.
Smith DR, Padilla WJ, Vier DC, Nemat-Nasser SC, Schultz S. Composite Medium with Simultaneously Negative Permeability and Permittivity. Phys. Rev. Lett. 2000; 84 :4184 - 74.
D. R. Smith, J. Gollub, J. J. Mock, W. J. Padilla, and D. Schurig, Calculation and measurement of bianisotropy in a split ring resonator metamaterial, Journal of Applied Physics 100 , 024507 (2006). - 75.
T. Driscoll, G. O. Andreev, D. N. Basov, S. Palit, S. Y. Cho, N. M. Jokerst, and D. R. Smith, Tuned permeability in terahertz split-ring resonators for devices and sensors, Appl. Phys. Lett. 91 , 062511 (2007). - 76.
A. K. Azad, A. J. Taylor, E. Smirnova, and J. F. O’Hara, Characterization and analysis of terahertz metamaterials based on rectangular split-ring resonators, Appl. Phys. Lett. 92 , 011119 (2008). - 77.
Rockstuhl C, Zentgraf T, Guo H, Liu N, Etrich C, Loa I, et al. Resonances of split-ring resonator metamaterials in the near infrared. Appl. Phys. B. 2006; 84 :219 - 78.
Le KQ, Bai J, Ngo QM, Chen P-Y. Fabrication and Numerical Characterization of Infrared Metamaterial Absorbers for Refractometric Biosensors. Journal of Elec Materi. 2017; 46 :668 - 79.
X. Zhao, J. Zhang, K. Fan, G. Duan, G. D. Metcalfe, M. Wraback, X. Zhang, and R. D. Averitt, Nonlinear terahertz metamaterial perfect absorbers using GaAs [Invited], Photon. Res., PRJ 4 , A16 (2016). - 80.
Asadchy VS, Díaz-Rubio A, Tretyakov SA. Bianisotropic metasurfaces: physics and applications. Nanophotonics. 2018; 7 :1069 - 81.
Liang F, Hanson GW, Yakovlev AB, Lovat G, Burghignoli P, Araneo R, et al. Dyadic Green’s Functions for Dipole Excitation of Homogenized Metasurfaces. IEEE Transactions on Antennas and Propagation. 2016; 64 :167 - 82.
Yatsenko VV, Maslovski SI, Tretyakov SA, Prosvirnin SL, Zouhdi S. Plane-wave reflection from double arrays of small magnetoelectric scatterers. IEEE Transactions on Antennas and Propagation. 2003; 51 :2 - 83.
Zhong S, He S. Ultrathin and lightweight microwave absorbers made of mu-near-zero metamaterials. Scientific Reports. 2013; 3 :2083 - 84.
Chen P-Y, Farhat M, Bağcı H. Graphene metascreen for designing compact infrared absorbers with enhanced bandwidth. Nanotechnology. 2015; 26 :164002 - 85.
Wang Z, Zhao L, Cai Y, Zheng S, Yin Y. A Meta-Surface Antenna Array Decoupling (MAAD) Method for Mutual Coupling Reduction in a MIMO Antenna System. Scientific Reports. 2018; 8 :3152 - 86.
Poddubny A, Iorsh I, Belov P, Kivshar Y. Hyperbolic metamaterials. Nature Photonics. 2013; 7 :948 - 87.
M. Y. Shalaginov, V. V. Vorobyov, J. Liu, M. Ferrera, A. V. Akimov, A. Lagutchev, A. N. Smolyaninov, V. V. Klimov, J. Irudayaraj, A. V. Kildishev, A. Boltasseva, and V. M. Shalaev, Enhancement of single-photon emission from nitrogen-vacancy centers with TiN/(Al,Sc)N hyperbolic metamaterial, Laser & Photonics Reviews 9 , 120 (2015). - 88.
Sakhdari M, Hajizadegan M, Farhat M, Chen P-Y. Efficient, broadband and wide-angle hot-electron transduction using metal-semiconductor hyperbolic metamaterials. Nano Energy. 2016; 26 :371 - 89.
P.-Y. Chen, M. Hajizadegan, M. Sakhdari, and A. Alù, Giant Photoresponsivity of Midinfrared Hyperbolic Metamaterials in the Photon-Assisted-Tunneling Regime, Phys. Rev. Applied 5 , 041001 (2016). - 90.
T. Guo, L. Zhu, P.-Y. Chen, and C. Argyropoulos, Tunable terahertz amplification based on photoexcited active graphene hyperbolic metamaterials [Invited], Opt. Mater. Express, OME 8 , 3941 (2018). - 91.
M. Hajizadegan, M. Sakhdari, and P.-Y. Chen, in Micro- and Nanotechnology Sensors, Systems, and Applications X (International Society for Optics and Photonics, 2018), p. 106390M. - 92.
N. Marcuvitz and M. I. of T. R. Laboratory, Waveguide Handbook (IET, 1951). - 93.
Rozanov KN. Ultimate thickness to bandwidth ratio of radar absorbers. IEEE Transactions on Antennas and Propagation. 2000; 48 :1230 - 94.
Yin X, Long C, Li J, Zhu H, Chen L, Guan J, et al. Ultra-wideband microwave absorber by connecting multiple absorption bands of two different-sized hyperbolic metamaterial waveguide arrays. Scientific Reports. 2015; 5 :15367 - 95.
E. F. Knott, J. F. Schaeffer, and M. T. Tulley, Radar Cross Section (SciTech Publishing, 2004). - 96.
Watts CM, Liu X, Padilla WJ. Metamaterial Electromagnetic Wave Absorbers. Advanced Materials. 2012; 24 :OP98 - 97.
Amin M, Siddiqui O, Farhat M, Khelif A. A perfect Fresnel acoustic reflector implemented by a Fano-resonant metascreen. Journal of Applied Physics. 2018; 123 :144502 - 98.
M. Amin, O. Siddiqui, and M. Farhat, Polarization-State Modulation in Fano Resonant Graphene Metasurface Reflector, Journal of Lightwave Technology 1 (2021). - 99.
Ouyang L, Wang W, Rosenmann D, Czaplewski DA, Gao J, Yang X. Near-infrared chiral plasmonic metasurface absorbers. Opt. Express. 2018; 26 :31484 - 100.
M. Amin, O. Siddiqui, W. Orfali, M. Farhat, and A. Khelif, Resonant Beam Steering and Carpet Cloaking Using an Acoustic Transformational Metascreen, Phys. Rev. Applied 10 , 064030 (2018). - 101.
Martini E, Mencagli M, Maci S. Metasurface transformation for surface wave control, Philosophical Transactions of the Royal Society A: Mathematical. Physical and Engineering Sciences. 2015; 373 :20140355 - 102.
Chen P-Y, Soric J, Padooru YR, Bernety HM, Yakovlev AB, Alù A. Nanostructured graphene metasurface for tunable terahertz cloaking, New J. Phys. 2013; 15 :123029 - 103.
L. Hsu, T. Lepetit, and B. Kanté, Extremely Thin Dielectric Metasurface for Carpet Cloaking, ArXiv:1503.08486 [Physics] (2015). - 104.
Buchnev O, Podoliak N, Kaczmarek M, Zheludev NI, Fedotov VA. Electrically Controlled Nanostructured Metasurface Loaded with Liquid Crystal: Toward Multifunctional Photonic Switch. Advanced Optical Materials. 2015; 3 :674 - 105.
Komar A, Paniagua-Domínguez R, Miroshnichenko A, Yu YF, Kivshar YS, Kuznetsov AI, et al. Dynamic Beam Switching by Liquid Crystal Tunable Dielectric Metasurfaces. ACS Photonics. 2018; 5 :1742 - 106.
Artiga X, Bresciani D, Legay H, Perruisseau-Carrier J. Polarimetric Control of Reflective Metasurfaces. IEEE Antennas and Wireless Propagation Letters. 2012; 11 :1489 - 107.
Wu X, Meng Y, Wang L, Tian J, Dai S, Wen W. Anisotropic metasurface with near-unity circular polarization conversion. Appl. Phys. Lett. 2016; 108 :183502 - 108.
Zhu HL, Cheung SW, Chung KL, Yuk TI. Linear-to-Circular Polarization Conversion Using Metasurface. IEEE Transactions on Antennas and Propagation. 2013; 61 :4615 - 109.
Koschny T, Kafesaki M, Economou EN, Soukoulis CM. Effective Medium Theory of Left-Handed Materials. Phys. Rev. Lett. 2004; 93 :107402 - 110.
R. Liu, T. J. Cui, D. Huang, B. Zhao, and D. R. Smith, Description and explanation of electromagnetic behaviors in artificial metamaterials based on effective medium theory, Phys. Rev. E 76 , 026606 (2007). - 111.
C. R. Simovski, On electromagnetic characterization and homogenization of nanostructured metamaterials, J. Opt. 13 , 013001 (2010). - 112.
M. A. El-Aasser, Design optimization of nanostrip metamaterial perfect absorbers, JNP 8 , 083085 (2014). - 113.
Hedayati MK, Javaherirahim M, Mozooni B, Abdelaziz R, Tavassolizadeh A, Chakravadhanula VSK, et al. Design of a Perfect Black Absorber at Visible Frequencies Using Plasmonic Metamaterials. Advanced Materials. 2011; 23 :5410 - 114.
Liu D, Wang L, Cui Q, Guo LJ. Planar Metasurfaces Enable High-Efficiency Colored Perovskite Solar Cells. Advanced Science. 2018; 5 :1800836 - 115.
D. B. Durham, S. R. Loria, F. Riminucci, K. Kanellopulos, X. Shen, F. Ciabattini, A. Mostacci, P. Musumeci, A. M. Minor, S. Cabrini, and D. Filippetto, in Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVIII (International Society for Optics and Photonics, 2020), p. 1146222. - 116.
Locatelli A, Capobianco A-D, Midrio M, Boscolo S, De Angelis C. Graphene-assisted control of coupling between optical waveguides. Opt. Express. 2012; 20 :28479 - 117.
Farhat M, Rockstuhl C, Bağcı H. A 3D tunable and multi-frequency graphene plasmonic cloak, Opt. Express, OE. 2013; 21 (12592) - 118.
Filter R, Farhat M, Steglich M, Alaee R, Rockstuhl C, Lederer F. Tunable graphene antennas for selective enhancement of THz-emission, Opt. Express, OE. 2013; 21 (3737) - 119.
A. Vakil and N. Engheta, Fourier optics on graphene, Phys. Rev. B 85 , 075434 (2012). - 120.
Gan X, Mak KF, Gao Y, You Y, Hatami F, Hone J, et al. Strong Enhancement of Light–Matter Interaction in Graphene Coupled to a Photonic Crystal Nanocavity. Nano Lett. 2012; 12 :5626 - 121.
Amin M, Farhat M, Baǧcı H. A dynamically reconfigurable Fano metamaterial through graphene tuning for switching and sensing applications. Scientific Reports. 2013; 3 :2105