We theoretically investigate the classical analog of electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) in a planar metamaterial at optical frequency, which originates from destructive and constructive interference between dark and radiative elements.The metamaterial consists of two coupled resonators with different geometries.An EIT-like transparent window with low absorption is observed and found to be strongly affected by resonant states of the resonators.The transition between the EIT and EIA is achieved by changing the split width and coupling distance.The absorption is enhanced up to 2.5 times compared with the dipolar case.The excitation of the dark mode is very important for EIT-and EIA-like responses of the proposed metamaterial.The EIT and EIA phenomena offer a potential method for manipulating electromagnetic response in metamaterial-based devices.
We theoretically investigate the classical analog of electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) in a planar metamaterial at optical frequency, which originates from destructive and constructive interference between dark and radiative elements.The metamaterial consists of two coupled resonators with different geometries.An EIT-like transparent window with low absorption is observed and found to be strongly affected by resonant states of the resonators.The transition between the EIT and EIA is achieved by changing the split width and coupling distance.The absorption is enhanced up to 2.5 times compared with the dipolar case.The excitation of the dark mode is very important for EIT-and EIA-like responses of the proposed metamaterial.The EIT and EIA phenomena offer a potential method for manipulating electromagnetic response in metamaterial-based devices.
In this paper, based on the constructive interference of plasmonic dipolar and quadrupolar modes, a classical analogue of electromagnetically induced absorption (EIA) is demonstrated theoretically in a stacked metamaterial consisting of a short metal strip (which acts as a bright resonator) and a long metal strip (acting as a dark resonator), which has been reported to support the electromagnetically induced transparency (EIT) effect. The transition from EIA to EIT can be clearly observed in the absorbance spectra via varying the vertical spacing between two resonant oscillators. With the help of the coupled two-oscillator model, the phase shift between the bright and dark resonance modes is calculated by fitting the simulated absorbance spectra, which reveals the physical mechanisms behind constructive and destructive interference effects in EIT/EIA metamaterials.
Classic analog of the electromagnetically induced transparency (EIT) in metamaterials has been demonstrated extensively by its attractive potential applications in light storage, slow light and sensing. However, the counterpart of EIT, electromagnetically induced absorption (EIA) has been studied rarely in coupled metamaterial systems. Here, we present the observation of the EIA effect in a vertically coupled three-resonator metamaterial. A well-defined absorption resonance is developed in the EIT window enabling a unique double-peak transparency, due to the magnetic resonance induced by the near-field coupling of the three resonators. The analog of EIA opens up a new route to advanced photonics devices.
In this paper, we theoretically demonstrate that electromagnetic transparency can be induced by optical magnetism in a metamaterial, which is composed of metamolecules. Each metamolecule consists of a metallic split-ring resonator, as one bright meta-atom (which is optically magnetic), and also a cut-wire pair, as one dark meta-atom (which is optically nonmagnetic). It is found that magnetic resonances occur at optical frequencies due to the local magnetic interaction between ``bright'' meta-atoms and ``dark'' meta-atoms; thereafter, a transparency window emerges upon the original absorption background. The phenomenon is similar to the electromagnetically induced transparency (EIT) in atomic three-level systems, and a microscopic picture is given to compare it with the EIT. Furthermore, low loss and slow light in this metamaterial have also been verified. The investigations may achieve potential applications on integrated optical circuits.
Metamaterials, or artificial materials with optical properties not known for natural materials, have recently been used to demonstrate unusual optical phenomena, such as negative refraction, perfect lenses, subwavelength components, and electromagnetic invisibility cloaks. Most of the metamaterials designed to date are periodic structures containing a single resonating element in each unit cell, such as a split-ring resonator (SRR), a cutwire, or a slab-wire pair [1]. In this contribution, we demonstrate that a metamaterial with two coupled SRRs can exhibit an effect reminiscent of electromagnetically induced transparency (EIT), a coherent process normally observed in three-level atomic media [2]. Due to this process, a small transparency window with low absorption appears in the spectral response of the metamaterial. Simultaneously, extremely steep normal dispersion is observed in the transparency window, which is useful for slow-light applications.
Using a planar metamaterial, which consists of two silver strips, we theoretically demonstrate the plasmonic electromagnetically-induced transparency (EIT)-like spectral response at optical frequencies. The two silver strips serve as the bright modes, and are excited strongly by the incident wave. Based on the weak hybridization between the two bright modes, a highly-dispersive plasmonic EIT-like spectral response appears in our scheme. Moreover, the group index is higher than that of another scheme which utilizes the strong coupling between the bright and dark modes.
Slow light technique has significant potential applications in many contemporary photonic device developments for integrated all-optical circuit, such as buffers, regenerators, switches and interferometers. In this paper, we present an efficient coupling mechanism of an electromagnetically induced transparency like (EIT-like) effect in an all-dielectric nano-metamaterial. This EIT-like effect is generated by destructive interference between a radiative Fabry-Perot (FP) mode and a dark waveguide (WG) mode, which is based on a combined structure of a dielectric grating and multilayer films. The dark WG mode is excited by guided mode of dielectric grating instead of radiative FP mode. In analogy to the molecular transition process, the FP mode, guided mode and WG mode are denoted by excited states of |1〉, |2〉 and |3〉. The two coupling pathways of the EIT-like effect in our metamaterial are |0〉 → |1〉 and |0〉 → |2〉 → |3〉 → |1〉, where |0〉 is the ground state. The simulated resonant wavelength of WG mode is consistent with theoretical result. We further confirm this EIT-like effect through a two-oscillator coupling analysis. We achieve a group refractive index of 913.6 by adjusting these two modes coupling of the EIT-like effect, which is useful for developing slow light device. This work provides a valuable solution to realize electromagnetically induced transparency in all-dielectric nanomaterial.