Analogs of Electromagnetically Induced Transparency (EIT) in metamaterial have undoubtedly become a research hotspot in recent years. In this paper, we summarized some of the literature on EIT published to date and compared their performance. Then, we designed two kinds of metamaterials using aluminum and silicon. Both have the similar glasses-shaped structure of a periodic lattice with one bar resonator and two split ring resonators. We analyzed and compared the EIT performance in the near infrared waveband of these two metamaterials. The metallic EIT metamaterials with large radiation loss and ohmic heat loss have a smaller Q-factor than the dielectric counterpart with less energy loss, while having a higher sensitivity toward the ambient refractive index. The Q-factor of our designed aluminum metamaterial and silicon metamaterial are 10.06 and 412.6, respectively. Their sensitivities are 1642.97 nm/RIU and 433.05 nm/RIU, respectively, which are higher than most of their counterparts in the same waveband in the other literature. For the application of slow light, the dielectric metamaterials with higher Q-factor are far superior to the metallic metamaterials in the same waveband and comparable propagation distance. The group index of the aluminum metamaterial is 42.9, and the group delay is 0.01 ps in the near infrared waveband. For the silicon metamaterial, the group index is approximately 1907.1, and the group delay is 0.89 ps within the transmission window in the near infrared waveband; these values are both higher than most counterparts in the same waveband in other literature. The EIT metamaterials that we designed have excellent performance, and to the best of our knowledge, this paper presents the first detailed comparison of EIT metamaterials made of dielectric and metal with similar structure; this paper may have certain instructive meaning for further research on metamaterial analogues of EIT in the future.
Analogs of Electromagnetically Induced Transparency (EIT) in metamaterial have undoubtedly become a research hotspot in recent years. In this paper, we summarized some of the literature on EIT published to date and compared their performance. Then, we designed two kinds of metamaterials using aluminum and silicon. Both have the similar glasses-shaped structure of a periodic lattice with one bar resonator and two split ring resonators. We analyzed and compared the EIT performance in the near infrared waveband of these two metamaterials. The metallic EIT metamaterials with large radiation loss and ohmic heat loss have a smaller Q-factor than the dielectric counterpart with less energy loss, while having a higher sensitivity toward the ambient refractive index. The Q-factor of our designed aluminum metamaterial and silicon metamaterial are 10.06 and 412.6, respectively. Their sensitivities are 1642.97 nm/RIU and 433.05 nm/RIU, respectively, which are higher than most of their counterparts in the same waveband in the other literature. For the application of slow light, the dielectric metamaterials with higher Q-factor are far superior to the metallic metamaterials in the same waveband and comparable propagation distance. The group index of the aluminum metamaterial is 42.9, and the group delay is 0.01 ps in the near infrared waveband. For the silicon metamaterial, the group index is approximately 1907.1, and the group delay is 0.89 ps within the transmission window in the near infrared waveband; these values are both higher than most counterparts in the same waveband in other literature. The EIT metamaterials that we designed have excellent performance, and to the best of our knowledge, this paper presents the first detailed comparison of EIT metamaterials made of dielectric and metal with similar structure; this paper may have certain instructive meaning for further research on metamaterial analogues of EIT in the future.
An analogy of electromagnetically induced transparency (EIT) based on all-dielectric metamaterial is theoretically demonstrated in this paper. The U-shaped Silicon-based metamaterial unit cell comprises a dipole antenna supported by one horizontal nanoscale bar and a quadrupolar antenna supported by two vertical nanoscale bars. The near-field coupling between the two antennas and the reduction of absorption loss lead to a narrow EIT-like transmission window with a high quality-factor of 130, which exhibits a refractive index sensitivity with a figure-of-merit of 29. The group delay of 0.75 ps and the group index of 2035 are obtained in the transmission window. Due to these unique optical properties, the proposed metamaterial structure can find many applications including slow-light devices, optical sensors, enhancement of non-linear processes, and storage of quantum information.
We investigate numerically an analog of electromagnetically induced transparency (EIT) in an all-dielectric metamaterial-waveguide (ADMW) that consists of a two-dimensional silicon rod array on quartz slab waveguide. The EIT-like response is achieved by the destructive interference between a broad magnetic resonance and a narrow guide mode resonance. By tailoring the guided mode through the thickness of the slab waveguide or the lattice period of the metamaterial, an EIT-like transmission window is achieved with both high Q-factor (>104) and high transmission (>94%). And the group refractive index at the EIT-like resonance of the ADMW can be up to several thousands. These results demonstrate that the proposed ADMW has potential applications in low-loss slow-light based devices, bio-chemical sensing, and optical modulations.
We investigated numerically the electromagnetically induced transparency (EIT) behavior with the maximum Q factor is up to 28000 in a metal-dielectric metamaterial. It composed of two layers, a metallic strip as bright mode stacked above a dielectric rod as another bright mode. The coherent coupling between the broad electric dipole induced by the metal strip and the narrow toroidal dipole induced by the dielectric rod leads to the destructive interference, then introduces a transparency window. Interestingly, the EIT window could be effectively influenced by varying parameters of the two layers and the thickness of middle spacer. This process can be explained by using two-particle model. Furthermore, the radiation loss is greatly suppressed within the EIT windows and the slow light effect is improved a lot. These excellent properties also provide an effective platform for the filters and sensitive chemical and biological sensors in the optical range.
The electromagnetically induced transparency (EIT), which is a result of destructive interference between different excitation paths in a three-energy-level atomic medium, makes opaque probe light transparent over a range of frequencies. As this EIT effect is usually accompanied with strong dispersion, it has potential applications such as slow light propagation, optical buffering, nonlinear optics, optical sensing, etc. However, for conventional quantum EIT effect which requires stable gas lasers and low temperature environment, the implementation of EIT in chip-scale applications is severely hampered by the scathing experimental requirements. Recently, the EIT-like effect in metamaterials, which are constructed by designing the artificial subwavelength functional elements and arranging the spatial sequences, attracts tremendous attention because of its advantages, such as room temperature manipulability, large bandwidth, and small sizes. In addition, the high-quality factor(Q) value obtained by EIT-like effect has great significance in designing the metamaterial-based devices. In this paper, we design an EIT-like metamaterial with such a structure. The unit cell of the proposed metamaterial is constructed by two asymmetric silicon blocks embedded on a silicon dioxide substrate. Meanwhile, we analyze its optical properties and EIT-like effects by using three-dimension (3D) FDTD method. Based on the coupled Lorentz model, the EIT-like effect of the designed metamaterial is investigated. Then, by employing the electric field distribution on the surface of the metamaterial, and combining with the three-level atomic system, the mechanism of the EIT-like effect is analyzed in detail. We find that the EIT-like effect in the proposed metamaterial has high Q value (Q ≈ 8616) and the high transmission (T = 96%). By changing the length of the silicon block to destroy the asymmetry of the metamaterial structure, an active tuning EIT-like effect is realized. Furthermore, the metamaterial structure has the advantages of low loss, easy preparation, and active-controllability. This study represents an innovative approach to designing the EIT-like metamaterial, which is expected to be useful for designing active tunable slow-light devices and highly sensitive optical sensors.
In this work, using finite-difference time-domain method, we propose and numerically demonstrate a novel way to achieve electromagnetically induced transparency (EIT) phenomenon in the reflection spectrum by stacking two different types of coupling effect among different elements of the designed metamaterial. Compared with the conventional EIT-like analogues coming from only one type of coupling effect between bright and dark meta-atoms on the same plane, to our knowledge the novel approach is the first to realize the optically active and precise control of the wavelength position of EIT-like phenomenon using optical metamaterials. An on-to-off dynamic control of the EIT-like phenomenon also can be achieved by changing the refractive index of the dielectric substrate via adjusting an optical pump pulse. Furthermore, in near infrared region, the metamaterial structure can be operated as an ultra-high resolution refractive index sensor with an ultra-high figure of merit (FOM) reaching 3200, which remarkably improve the FOM value of plasmonic refractive index sensors. The novel approach realizing EIT-like spectral shape with easy adjustment to the working wavelengths will open up new avenues for future research and practical application of active plasmonic switch, ultra-high resolution sensors and active slow-light devices.
In this manuscript, we experimentally demonstrate magnetically coupled electromagnetically induced transparency (EIT) analogy effect inside dielectric metamaterial. In contrast to previous studies employed different metallic topological microstructures to introduce dissipation loss change, barium strontium titanate, and calcium titanate (CaTiO3) are chosen as the bright and dark EIT resonators, respectively, due to their different intrinsic dielectric loss. Under incident magnetic field excitation, dielectric metamaterial exhibits an EIT-type transparency window around 8.9 GHz, which is accompanied by abrupt change of transmission phase. Numerical calculations show good agreement with experiment spectra and reveal remarkably increased group index, indicating potential application in slow light.