Materials research plays a vital role in transforming breakthrough scientific ideas into next-generation technology. Similar to the way silicon revolutionized the microelectronics industry, the proper materials can greatly impact the field of plasmonics and metamaterials. Currently, research in plasmonics and metamaterials lacks good material building blocks in order to realize useful devices. Such devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially metals. There are many materials, other than conventional metallic components such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent conducting oxides, perovskite oxides, metal nitrides, silicides, germanides, and 2D materials such as graphene. This review provides a summary of the recent developments in the search for better plasmonic materials and an outlook of further research directions.

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Alternative Plasmonic Materials: Beyond Gold and Silver

Preface. 1. Plasmas and Dust. 2. Charging Mechanisms and Experiments. 3. Space Observations. 4. Multispecies Formalism and Waves. 5. Electrostatic Modes. 6. Electromagnetic Modes. 7. Fluctuating Dust Charges. 8. Self-Gravitation. 9. Mass and Size Distributions. 10. Other Modes. 11. Conclusions and Outlook. Bibliography. Index.

https://physicstoday.scitation.org/doi/pdf/10.1063/1.1404853

Waves in Dusty Space Plasmas

Metasurfaces are artificially structured thin films with unusual properties on demand. Different from metamaterials, the metasurfaces change the electromagnetic waves mainly by exploiting the boundary conditions, rather than the constitutive pa-rameters in three dimensional (3D) spaces. Despite the intrinsic similarities in the operational principles, there is not a universal theory available for the understanding and design of metasurface-based devices. In this article, we propose the concept of metasurface waves (M-waves) and provide a general theory to describe the principles of them. Most importantly, it is shown that the M-waves share some fundamental properties such as extremely short wavelength, abrupt phase change and strong chromatic dispersion, which make them different from traditional bulk waves. It is shown that these properties can enable many important applications such as subwavelength imaging and lithography, planar optical devices, broadband anti-reflection, absorption and polarization conversion. Our results demonstrated unambiguously that traditional laws of diffraction, refraction, reflection and absorption should be revised by using the novel properties of M-waves. The theory provided here may pave the way for the design of new electromagnetic devices and further improvement of metasurfaces. The exotic properties of metasurfaces may also form the foundations for two new sub-disciplines called “subwavelength surface electromagnetics” and “subwavelength electromagnetics”.

Principles of electromagnetic waves in metasurfaces

The changing balance of forces at the nanoscale offers the opportunity to develop a new generation of spatially reconfigurable nanomembrane metamaterials in which electromagnetic Coulomb, Lorentz and Ampere forces, as well as thermal stimulation and optical signals, can be engaged to dynamically change their optical properties. Individual building blocks of such metamaterials, the metamolecules, and their arrays fabricated on elastic dielectric membranes can be reconfigured to achieve optical modulation at high frequencies, potentially reaching the gigahertz range. Mechanical and optical resonances enhance the magnitude of actuation and optical response within these nanostructures, which can be driven by electric signals of only a few volts or optical signals with power of only a few milliwatts. We envisage switchable, electro-optical, magneto-optical and nonlinear metamaterials that are compact and silicon-nanofabrication-technology compatible with functionalities surpassing those of natural media by orders of magnitude in some key design parameters.

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Reconfigurable nanomechanical photonic metamaterials

We present the design, analysis and measurements of a polarization-insensitive tunable metamaterial absorber with varactor diodes embedded between metamaterial units. The basic unit shows excellent absorptivity in the designed frequency band over a wide range of incident angles. By regulating the reverse bias voltage on the varactor diode, the absorption frequency of the designed unit can be controlled continuously. The absorption mechanism is interpreted using the electromagnetic-wave interference theory. When the metamaterial units are placed along two orthogonal directions, the absorber is insensitive to the polarization of incident waves. The tunability of the absorber has been verified by experimental results with the measured bandwidth of 1.5?GHz (or relative bandwidth of 30%).

https://iopscience.iop.org/article/10.1088/1367-2630/15/4/043049/pdf

A tunable metamaterial absorber using varactor diodes

Metamaterial research is an extremely important global activity that promises to change our lives in many different ways. These include making objects invisible and the dramatic impact of metamaterials upon the energy and medical sectors of society. Behind all of the applications, however, lies the business of creating metamaterials that are not going to be crippled by the kind of loss that is naturally heralded by use of resonant responses in their construction. This review sets out some solutions to the management of loss and gain, coupled to controlled and nonlinear behavior, and discusses some critical consequences concerning stability. Under the general heading of active and tunable metamaterials, an international spectrum of authors collaborates here to present a set of solutions that addresses these issues in several directions. As will be appreciated, the range of possible solutions is really fascinating, and it is hoped that these discussions will act as a further stimulus to the field.

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Active and tunable metamaterials

Resonant excitation of microwave acoustic modes in n-GaAs film

In this article we have investigated frequency multiplication in the crystals of strontium titanate paraelectric at a temperature of 77 K. Frequency dispersion affects the process of harmonics generation. It has been shown that the efficiency of higher harmonics generation is high and it is equal to 30%. One can perform the selective extraction of certain harmonic by means of an optimal choice of the crystal length.

Frequency multiplication of terahertz radiation in the crystals of strontium titanate paraelectric

The electronic structure of a delta-doped quantum well of Si in GaAs matrix is studied at difierent temperatures. The calculation is carried out self-consistently in the framework of the Hartree approximation. The energy levels and the occupation numbers of the discrete states are reported. DOI: 10.2529/PIERS061006210621 The doping of semiconductors down to atomic resolution (- doping) has recently become possible as a natural development of the increasing precision of modern MBE growth techniques. Work on --doped systems was primarily on n-type structures (1{6). The knowledge of the energy level structure is important in the theoretical aspects as well as for potential device applications (7,8). In this particular, the B --doped Si QW has been recently investigated (9{13). In Ref. (13), the authors study the efiect of the temperature in the electronic structure of this system. From the results of that work it is concluded that this efiect qualitatively changes the energy structure. In this paper, we are going to present the flrst self-consistent calculation of the electronic en- ergy structure for the Si --doped QW in GaAs in which the temperature efiect in the statistical distribution of charges is considered. The calculation is performed within the framework of the Efiective Mass Theory and one band Envelope Function Approximation (EFA). Thus, the corresponding wave equation is i ~ 2 2m ⁄ d 2 dz 2 Fi(z) + V (z)Fi(z) = EiFi(z): (1) Fi(z) is the z-dependent envelope function, Ei is the i-th energy level and m ⁄ is the efiective mass. The spatial band bending is described by the solution of the Poisson equation. We take the energy origin at z = 0(V (0) = 0) with the electric fleld tending to zero when z tends to inflnity. Integrating twice and using the Fubini-Lebesgue theorem to change the order of integration, the Poisson equation adopts a simple form, i.e., V (z) = 4…e

Electronic Structure as a Function of Temperature for Si --doped Quantum Wells in GaAs

The space charge wave propagation in thin n-GaAs films has been considered within a framework of different quasi-hydrodynamic balance models. A comparative study of the dependencies k(omega) of a complex longitudinal wave number on frequency, which are obtained from different balance equation models are presented and discussed. It has been demonstrated that the model where the balance equations are written for different valleys directly seems to be the most correct. The balance models based on averaging over the valleys may lead to incorrect results in the case of long distances of propagation of space charge waves. When the thermal conductivity term is taken into account and the length of the system is short, the averaged balance models can get satisfactory results

Volodymyr Grimalsky

Papers

Active and tunable metamaterials

Resonant excitation of microwave acoustic modes in n-GaAs film

Frequency multiplication of terahertz radiation in the crystals of strontium titanate paraelectric

Electronic Structure as a Function of Temperature for Si --doped Quantum Wells in GaAs

Dispersion Relation for Two-Valley QuasiHydrodynamic Models in SCWs Propagation in n-GaAs Thin Films