scholarly journals Electromagnetically induced transparency in plasma

2001 ◽  
Vol 19 (2) ◽  
pp. 175-179 ◽  
Author(s):  
B. ERSFELD ◽  
D.A. JAROSZYNSKI

The coupled propagation of two electromagnetic waves in plasma is studied to establish the conditions for induced transparency. Induced transparency refers to the situation where both waves propagate unattenuated, although the frequency of one (or both) of them is below the plasma frequency so that it could not propagate in the absence of the other. The effect is due to the interaction of the waves through their beat, which modulates both the electron mass and, by exciting longitudinal plasma oscillations, their number density, and thus the plasma frequency. Starting from a relativistic fluid description, a dispersion relation for plane waves of weakly relativistic intensities is derived, which takes into account the polarization of the waves and the nonlinearities with respect to both their amplitudes. This serves as a basis for the exploration of the conditions for induced transparency and the modes of propagation.

Weyl has shown that any gravitational wave of small amplitude may be regarded as the result of the superposition of waves of three types, viz.: (i) longitudinal-longitudinal; (ii) longitudinal-transverse; (iii) transverse-transverse. Eddington carried the matter much further by showing that waves of the first two types are spurious; they are “merely sinuosities in the co­ordinate system,” and they disappear on the adoption of an appropriate co-ordinate system. The only physically significant waves are transverse-transverse waves, and these are propagated with the velocity of light. He further considers electromagnetic waves and identifies light with a particular type of transverse-transverse wave. There is, however, a difficulty about the solution as left by Eddington. In its gravitational aspect light is not periodic. The gravitational potentials contain, in addition to periodic terms, an aperiodic term which increases without limit and which seems to indicate that light cannot be propagated indefinitely either in space or time. This is, of course, explained by noting that the propagation of light implies a transfer of energy, and that the consequent change in the distribution of energy will be reflected in a cumulative change in the gravitational field. But, if light cannot be propagated indefinitely, the fact itself is important, whatever be its explana­tion, for the propagation of light over very great distances is one of the primary facts which the relativity theory or any like theory must meet. In endeavouring to throw further light on this question, it seemed desirable to avoid the assumption that the amplitudes of the waves are small; terms neglected on this ground might well have a cumulative effect. All the solu­tions discussed in this paper are exact.


1993 ◽  
Vol 49 (2) ◽  
pp. 227-235 ◽  
Author(s):  
S. T. Ivanov ◽  
K. M. Ivanova ◽  
E. G. Alexov

Electromagnetic wave propagation along the interface between a magnetoactive plasma and a metallic screen is investigated analytically and numerically. It is shown that the waves have a Rayleigh character: they are superpositions of two partial waves. It is concluded that electromagnetic waves propagate only at frequencies lower than min (ωp, ωc), where ωpis the plasma frequency and ωcis the cyclotron frequency. The field topology is found, and the physical character of the waves is discussed.


2020 ◽  
Vol 30 (2) ◽  
pp. 189
Author(s):  
Pham The Linh ◽  
Nguyen Thi Viet Ninh ◽  
Nguyen Dinh Quang ◽  
Tran Tien Lam ◽  
Nguyen Van Ngoc ◽  
...  

Metamaterial (MM) is emerging as a promising approach to manipulate electromagnetic waves, spanning from radio frequency to the optical region. In this paper, we employ an effect called electromagnetically-induced transparency (EIT) in all-dielectric MM structures to create a narrow transparent window in opaque broadband of the optical region (580-670 nm). Using dielectric materials instead of metals can mitigate the large non-radiative ohmic loss on the metal surface. The unit-cell of MM consists of Silicon (Si) bars on Silicon dioxide (SiO\(_{2}\)) substrate, in which two bars are directed horizontally and one bar is directed vertically. By changing the relative position and dimension of the Si bars, the EIT effect could be achieved. The optical properties of the proposed MM are investigated numerically using the finite difference method with commercial software Computer Simulation Technology (CST). Then, characteristic parameters of MM exhibiting EIT effect (EIT-MM), including Q-factor, group delay, are calculated to evaluate the applicability of EIT-MM to sensing and light confinement.


2019 ◽  
Vol 33 (33) ◽  
pp. 1950404 ◽  
Author(s):  
Tran Van Huynh ◽  
Bui Son Tung ◽  
Bui Xuan Khuyen ◽  
Nguyen Thanh Tung ◽  
Vu Dinh Lam

Metamaterials (MMs) represent a group of exciting artificial materials that interact with electromagnetic waves in unnatural ways. The motivation behind MM research arises not only from fundamental interest in their unique physical properties but also from the desire of creating smarter materials for advanced technological applications. Despite an abundance of studies on numerous shapes, sizes and operating frequencies, the use of conventional metal-dielectric components makes the post-fabrication physical properties of MMs unalterable. Therefore, the integration of other nonlinear materials is necessary for exploring the functional limits of MMs. In this regard, a mono-layer of carbon, the so-called graphene, with its unique electrical conductivity is identified as a promising candidate. This review discusses the recent progress on tunable graphene-based THz MMs for perfect absorption and electromagnetically-induced transparency effects. A short overview of prospect challenges and tendencies is also given for future development of graphene-integrated MMs towards upcoming smart meta-devices.


2016 ◽  
Vol 2 (2) ◽  
pp. e1501142 ◽  
Author(s):  
Xueqian Zhang ◽  
Quan Xu ◽  
Quan Li ◽  
Yuehong Xu ◽  
Jianqiang Gu ◽  
...  

Control over surface plasmons (SPs) is essential in a variety of cutting-edge applications, such as highly integrated photonic signal processing systems, deep-subwavelength lasing, high-resolution imaging, and ultrasensitive biomedical detection. Recently, asymmetric excitation of SPs has attracted enormous interest. In free space, the analog of electromagnetically induced transparency (EIT) in metamaterials has been widely investigated to uniquely manipulate the electromagnetic waves. In the near field, we show that the dark mode coupling mechanism of the classical EIT effect enables an exotic and straightforward excitation of SPs in a metasurface system. This leads to not only resonant excitation of asymmetric SPs but also controllable exotic SP focusing by the use of the Huygens-Fresnel principle. Our experimental findings manifest the potential of developing plasmonic metadevices with unique functionalities.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ying Huang ◽  
Kenta Nakamura ◽  
Yuma Takida ◽  
Hiroaki Minamide ◽  
Kazuhiro Hane ◽  
...  

AbstractElectromagnetically induced transparency (EIT) analogs in classical oscillator systems have been investigated due to their potential in optical applications such as nonlinear devices and the slow-light field. Metamaterials are good candidates that utilize EIT-like effects to regulate optical light. Here, an actively reconfigurable EIT metamaterial for controlling THz waves, which consists of a movable bar and a fixed wire pair, is numerically and experimentally proposed. By changing the distance between the bar and wire pair through microelectromechanical system (MEMS) technology, the metamaterial can controllably regulate the EIT behavior to manipulate the waves around 1.832 THz, serving as a dynamic filter. A high transmittance modulation rate of 38.8% is obtained by applying a drive voltage to the MEMS actuator. The dispersion properties and polarization of the metamaterial are also investigated. Since this filter is readily miniaturized and integrated by taking advantage of MEMS, it is expected to significantly promote the development of THz-related practical applications such as THz biological detection and THz communications.


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