In this paper, an electromagnetically induced transparency (EIT) metamaterial with the performances of polarization independence and multi-transmission windows is proposed. First, we design an EIT with a single transmission window, which is composed of an H-shaped structure and two split-ring resonators (SRRs). Then, by sequentially rotating the unit by 90°, a new EIT structure with rotational symmetry is obtained. The results show that the new EIT structure has the characteristics of polarization independence and multiple transmission windows, and each transmission window has a high maximum transmittance and group index. The first transmission window has a maximum group index of 88.9 and 98.9% maximum transmission. The maximum group indices of the second and third transmission windows are 117.9 and 215.3, and the peak transmissions are 89.9% and 97.4%, respectively. The multiple transmission windows with polarization independence widen the application scope of the proposed EIT metamaterial and are suitable for high-performance slow-wave devices with the above two requirements.
In this paper, an electromagnetically induced transparency (EIT) metamaterial with the performances of polarization independence and multi-transmission windows is proposed. First, we design an EIT with a single transmission window, which is composed of an H-shaped structure and two split-ring resonators (SRRs). Then, by sequentially rotating the unit by 90°, a new EIT structure with rotational symmetry is obtained. The results show that the new EIT structure has the characteristics of polarization independence and multiple transmission windows, and each transmission window has a high maximum transmittance and group index. The first transmission window has a maximum group index of 88.9 and 98.9% maximum transmission. The maximum group indices of the second and third transmission windows are 117.9 and 215.3, and the peak transmissions are 89.9% and 97.4%, respectively. The multiple transmission windows with polarization independence widen the application scope of the proposed EIT metamaterial and are suitable for high-performance slow-wave devices with the above two requirements.
Two simple polarization-independent electromagnetically-induced transparency (EIT) metamaterials are numerically and experimentally demonstrated at the terahertz region. The first structure is composed of two metal concentric rings on a substrate, while the second one is composed of one metal ring with a cross in it. The bright–bright coupling behavior appears in the two symmetric polarization-independent EIT structures while it is generally observed in asymmetrically structures. In addition, the large group index is extracted to verify the slow-light effect of the two EIT structures. These simple EIT structures may have potential applications in certain areas, including sensing, slow-light and filtering devices.
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.
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.
In this paper, an electromagnetically induced transparency metamaterial simultaneously coupled with the incident electric and magnetic fields is designed and presented theoretically, whereas its reconfigurability, slow-wave effect, low-loss, and polarization insensitivity are analyzed and discussed principally. Based on the tunable solid-state plasma, there is a transmission peak with a 92.06% transmission at 0.544 THz in State 1 and a transmission peak with a 92.84% transmission at 0.7535 THz in State 2, thus achieving a frequency shift of 0.2085 THz. The maximum group delay, group index, and delay-bandwidth product in State 1 or 2, which are 723.7 ps or 494.7 ps, 1024.1 or 700.1, and 48.5 or 36.1, respectively, and the excellent slow-wave effects are discussed. In addition, the low-loss and polarization insensitivity are realized by rotating the split-ring resonators 180° and twisting the planar structure 90°. Considering the unique features of the designed metamaterial, it can be extensively applied to slow-light devices, communication, sensors, and nonlinear 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.
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.