Polarization-insensitive electromagnetically induced transparency (EIT) based on ultra-thin coupling planar metamaterials has been numerically demonstrated. The height (h) of ultra-thin coupling planar metamaterials can reach to 1/94 λ, which is the thinnest height so far. Such ultra-thin EIT metamaterials can reduce the cost of production. When the angles of the incident electromagnetic wave are changed, the EIT metamaterials show polarization-insensitive characteristics. When the height of the EIT metamaterials gradually increases, the group index gradually decreases and the transmission peak value and h/λ gradually increase. All of above characteristics make the ultra-thin coupling EIT have potential application in slow light devices. In addition, using the coupling of the top and below layer has proposed a way to obtain ultra-thin metamaterials in the microwave region.
Polarization-insensitive electromagnetically induced transparency (EIT) based on ultra-thin coupling planar metamaterials has been numerically demonstrated. The height (h) of ultra-thin coupling planar metamaterials can reach to 1/94 λ, which is the thinnest height so far. Such ultra-thin EIT metamaterials can reduce the cost of production. When the angles of the incident electromagnetic wave are changed, the EIT metamaterials show polarization-insensitive characteristics. When the height of the EIT metamaterials gradually increases, the group index gradually decreases and the transmission peak value and h/λ gradually increase. All of above characteristics make the ultra-thin coupling EIT have potential application in slow light devices. In addition, using the coupling of the top and below layer has proposed a way to obtain ultra-thin metamaterials in the microwave region.
Abstract Based on graphene, an ultra-broadband electromagnetically induced transparency (EIT) window with dynamic tunability is realized in theory. Through altering the Fermi level of graphene that can be regulated by the external voltage, the EIT window and the EIT effect, especially the slow-wave effect, can be easily adjusted. Moreover, the bandwidth of the EIT window can be changed by the incidence angle, achieving the transformation from broadband to narrowband. At the same time, by discussing the polarization state and loss index, the characteristics of polarization insensitivity and low loss are proved. Additionally, the influences of other parameters are discussed, such as the relaxation time of graphene and coupling distance. These unique features enable the designed EIT metamaterial to be masterly applied to optical switches, optical modulators, and slow-light devices.
Based on solid-state plasma (SSP), an electromagnetically induced transparent (EIT) metamaterial is proposed. Simulations illustrate that the given metamaterial has the characteristics of adjustment, polarization insensitivity, and low dissipation. Because SSP can be coordinated in state I, the ideal transmittance frequency band can cover 8.0335–9.02531 GHz (a narrow band). If the regulatory status is switched to state II, that frequency region will alter to 9.7982–12.9275 GHz (a broad band). As SSP can be switched back and forth between states I and II under actual demand, the tailored EIT metamaterial can be achieved. The maximum group delays of state I and state II are 0.9437 ns and 0.5546 ns, respectively, and the maximum group refractive indices are 526.60 and 300.45, respectively, which conforms to its slow light characteristic. Regardless of how the polarization angle changes, the two transmission valleys of state I are at 7.9172 GHz and 10.4446 GHz, and the transmission peak is situated at 8.2091 GHz, and those values of state II are 9.3777 GHz, 13.9600 GHz, and 10.1920 GHz, respectively, which proves that the obtained EIT is polarization independent and also has a low dissipation factor. Such an EIT metamaterial has excellent properties in sensing, communication, slow light, and other fields.
We numerically demonstrate that an electromagnetically induced transparent (EIT) all-dielectric metamaterial with properties of polarization-independence and incident angle insensitivity can be achieved in terahertz regimes. The metamaterial cell is composed of two bi-air-hole cubes (BCs) with different sizes. The two BCs function as superradiant and subradiant resonators, respectively. Based on Mie-type destructive interferences between dielectric resonators, the EIT effect is induced at around 8.25 THz with the transmission peak close to 0.95. Moreover, the "two-particle" model is introduced to describe the EIT effect and the influence of couplings between the two BCs on the transmission spectra. Analytical results are in good agreement with numerical simulation results. Owing to the symmetry and uniformity of the metamaterial structure, polarization-independent and angle-insensitive properties can be achieved. In addition, the slow light characteristic of the metamaterial is also verified. Such an EIT scheme may have potential applications in low-loss slow light devices and bandpass filters.
Electromagnetically induced transparency is an optical phenomenon that is characterized by the elimination of the effect of a medium on a propagating beam of electromagnetic radiation in a specific frequency band. In this study, EIT was investigated at a proposed metamaterial with the dimensions milimeter and in the area of frequency of GHz. The computation results indicated that EIT with high transmission rate and high Q factor occurs in certain frequencies by breaking the symmetry in this structure. The sensitivity studies showed that the use of silver in the structure increases the quality factor so significantly that this quantity reaches 338 for gold and copper, while it reaches 677 for silver. In addition, By reducing the temperature, the transmission rate in the structure increases and reaches acceptable degree 98%. This structure can be an appropriate option for slow light usages, and it can be utilized for light amplification in microwave structures.
Abstract Based on the solid-state plasma (SSP), a metamaterial analog of electromagnetically induced transparency (EIT-like) with superior properties is theoretically proposed, including tunability, a large group index, and delay-bandwidth product (DBP), polarization independence, and low-loss. By exciting different specific parts of the SSP, the EIT-like peak frequency switches from 8.518 GHz with 90.92% transmissivity in state I to 11.26 GHz with 93.76% transmissivity in state II, i.e. a 2.742 GHz shift. Meanwhile, the metamaterial has 0.679 ns or 1.314 ns group delay, 453 or 876.1 group index, and 0.422 or 1 DBP in state I or III. Additionally, the transmission curves are the same under the circular polarization waves or linear polarization waves at any angle. The low-loss feature is likewise demonstrated. Therefore, the EIT-like metamaterial has superior properties for related applications, especially in slow light, sensing, switching, and communication.
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.