We present a broadband electromagnetically induced transparency-like (EIT-like) effect in a microwave waveguide system by employing a bright meta-atom side-coupled to a linear chain of dark meta-atoms with a hybridization bandgap (HBG). We find that such a configuration can generate a wideband EIT response of up to 145 MHz, covering 23.7% of the central frequency. We also show that the EIT bandwidth can even extend to 211 MHz by further broadening the HBG while keeping the device volume unchanged. We emphasize that the EIT-like meta-molecules are subwavelength structures with only about one tenth of the operating wavelength. Our findings will be beneficial for realizing compact broadband slow light components in communication systems.
We present a broadband electromagnetically induced transparency-like (EIT-like) effect in a microwave waveguide system by employing a bright meta-atom side-coupled to a linear chain of dark meta-atoms with a hybridization bandgap (HBG). We find that such a configuration can generate a wideband EIT response of up to 145 MHz, covering 23.7% of the central frequency. We also show that the EIT bandwidth can even extend to 211 MHz by further broadening the HBG while keeping the device volume unchanged. We emphasize that the EIT-like meta-molecules are subwavelength structures with only about one tenth of the operating wavelength. Our findings will be beneficial for realizing compact broadband slow light components in communication systems.
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.
Abstract Electromagnetically induced transparency (EIT) stems from a quantum system, where an opaque atomic medium appears the narrow transparent state within a wide absorption area. This phenomenon can be achieved by quantum interference of pumping light and detecting light at different energy levels of transitions. In the generation process of EIT effect, in addition to transparent state, the atomic medium is usually accompanied with a strong dispersion effect, which will bright about a significant reduction of light velocity, thus realizing many important applications, such as slow light propagations. Although the EIT effect has many important applications, its application scenarios are greatly limited due to the fact that EIT realization usually requires specific and complicated conditions, such as refrigeration temperature, high intensity laser, etc. Recently, the analogue of EIT effect in metamaterial has attracted increasing attentions due to its advantages such as controllable room temperature and large operating bandwidth. Metamaterial analogue of EIT effect has become a new research focus. In this article, we review current research progresses on EIT metamaterials. Firstly, we describe the theoretical models for analyzing EIT metamaterials, including the mechanical oscillator model and the equivalent circuit model. Then, we describe the simulations, designs and experiments of passive EIT metamaterials with fixed structures and active EIT metamaterials with tunable elements. Furthermore, the applications of EIT metamaterials in the areas of slow lights, sensings, absorptions and other fields are also reviewed. Finally, the possible directions and key issues of future EIT metamaterial researches are prospected.
Electromagnetically induced transparency-like (EIT-like) effect is a promising research area for applications of slow light, sensing and metamaterials. The EIT-like effect is generally formed by the destructive interference of bright-dark mode coupling and bright-bright mode coupling. There are seldom reports about EIT-like effect realized by the coupling of two dark modes. In this paper, we numerically and theoretically demonstrated that the EIT-like effect is achieved through dark-dark mode coupling of two waveguide resonances in a compound nanosystem with metal grating and multilayer structure. If we introduce |1⟩, |2⟩ and |3⟩ to represent the surface plasmon polaritons (SPPs) resonance, waveguide resonance in layer 2, and waveguide resonance in layer 4, the destructive interference occurs between two pathways of |0⟩→|1⟩→|2⟩ and |0⟩→|1⟩→|2⟩→|3⟩→|2⟩, where |0⟩ is the ground state without excitation. Our work will stimulate more studies on EIT-like effect with dark-dark mode coupling in other systems.
Electromagnetically induced transparency (EIT) has been extensively investigated in atomic systems, to control transmission through optical components and the velocities of ``slow light'' packets. The authors realize EIT using a metamaterial that turns transparent with the incidence of an auxiliary electromagnetic wave, in the same manner as from the original, atomic EIT effect. This approach could lead to applications including the storage of electromagnetic waves (the ultimate slowing of light) across a wide frequency range for optical computing.
Abstract The realization of electromagnetically induced transparency (EIT) on metamaterials has special properties, such as strong slow-light, frequency-selection and so on, which have allowed EIT to be widely used in the fields of slow-light, optical storages and filters. In this paper, a metamaterial with two pairs of split ring resonators and one cut-wire is designed to achieve dual-band EIT effect at 0.5–2.14 GHz and 0.4–2.10 GHz with independently tunable bandwidths of 1.64 GHz and 2.7 GHz, respectively. The coupled Lorentz model is adopted to principally study the coupling characteristics between dark and bright modes. It is shown that the coupling strength between the dark and bright modes could be modulated by the coupling distance, which make the dual-band transparent window could be independently modulated by only changing the coupling distance between the bright and dark mode. The group delay and energy storage are also simulated by setting the Gaussian pulse signal passing through the EIT structure. The results show that the group delay of the designed EIT structure is 16.9 times that of the same thickness of dielectric material. The manufactured metamaterial is tested in a microwave anechoic chamber. The experimental and theoretical results are well consistent. These results could be beneficial for the development of EIT research toward some up-and-coming novel slow-light, optical storage, sensor and optical filter applications.
We experimentally demonstrated a controllable electromagnetically induced transparency (EIT)-like spectral response at microwave frequencies in a planar metamaterial consisting of two identical split-ring resonators (SRRs) with side-by-side symmetry. In our scheme, phase coupling between the two SRRs (serving as the bright mode), which were excited strongly by the incident wave, was employed, and it was found that the EIT-like spectral response could be controlled by simply adjusting the incident angle. Thus, our scheme may be used for electromagnetic-wave switching. A high group index for slow-light application and a high quality factor could be obtained by simply controlling the incident angle.