Metamaterial-based analogous of electromagnetically induced transparency and application on solid-state sensing

In this paper, a general comparison is presented between time-domain and frequency-domain simulation schemes of phased arrays. A series of Vivaldi arrays are simulated with finite integral time-domain (FITD) and frequency-domain finite element method (FEM) in terms of its far field characteristic like radiation pattern and gain. Three finite arrays of 10 by 10, 20 by 20, and 30 by 30 are simulated using FITD. The results are compared with that of the same arrays by linear combination of a unit Vivaldi antenna simulated with FEM. It is concluded that for small arrays time domain is more accurate while for large ones frequency domain method is more superior in terms of computer time and memory.

The spatial resolutions of conventional THz TDS systems are limited by diffraction. In this work, we present a numerical analysis of apertureless THz pulse near-field microscopy (NFM), and successfully demonstrate that the THz NFM can have nanometer-scale resolution. For the numerical analysis we used CST MWS, a commercial software based on finite integral time domain (FITD) method. It is found that the THz near field is strongly localized around the probe tip as expected, which is of importance for nanometer resolution.

A novel strategy for screening early hepatocellular carcinoma (HCC) using a terahertz (THz) metamaterials (MMs) biosensor modified with the antibody against alpha-fetoprotein (AFP) is proposed. The designed biosensor consists of split-resonant-rings (SRRs) with double resonant frequencies that are optimized using the finite integration time domain (FITD) method and manufactured by a surface micromachining process. The experimental results indicate that the HCC biomarker AFP could be accurately distinguished with a concentration as low as 0.1 ng/mL via analyzing the shifts of double resonant frequencies. Meanwhile, specific detection of AFP-antigen in solution and HCC serum has been achieved through the antigen-antibody specific binding. These results demonstrate the sensitivity and specificity of THz MMs biosensor for molecular detection of trace cancer biomarkers in biochemical sensing. Furthermore, the sensitivity of specific cancer biomarkers can be further improved by optimizing the MM structure and applying the double resonant frequencies. Therefore, this approach may own great potential for special identification of early cancer molecules.

In this paper, a dual-layer metamaterial structure operating in the microwave band which is composed of nested split-ring resonators (SRRs) was designed. The electromagnetic transmission under two polarization modes are comparatively analyzed through the finite integral time domain method. By scrutinizing the electric field distribution on each resonance frequency, the physical mechanism of the electromagnetically induced transparency (EIT)-like effect is expounded, and the influence of the structure parameters was further investigated. The experimental results obtained from the microwave anechoic chamber closely match with the simulation results. The experimental findings suggest that the metamaterial structure has potential applications in the detection of solid material permittivity.

A dual-band asymmetric transmission device based on the nonlinear electromagnetically induced transparency (EIT) effect is presented in this paper. The device structure is composed of two P-type branches and two split ring resonators (SRRs). Dual-band EIT effect is induced based on the destructive interferences between scattering fields of the SRRs and branches in a microstrip transmission line system. Moreover, nonlinear varactor diodes and the asymmetric absorption resistor are added to EIT structure based on microstrip line couplings, which results in the asymmetric transmission property. The 10 dB and 7.5 dB transmission light contrasts at the frequencies of 0.85 GHz and 0.95 GHz with the input power of − 3 dBm are demonstrated experimentally. Such low-loss, broadband and high-contrast asymmetric transmission device results from the EIT mechanism, which possesses narrower, sharper and higher transmittance features. Such results will be very beneficial for new nonlinear electromagnetic devices.

A terahertz metamaterial structure consisting of two U-shaped split-ring resonators and a horizontal cut-line resonator is designed for realizing the electromagnetically induced transparency (EIT) effect and the Fano resonance effect. The genesis of the EIT and Fano resonance bifunctionality is illustrated by combining the near-field distribution analysis of transparent windows and transmission dips. Interestingly, the bifunctional dual-band transparency effect could transform into a single-functional single-band transparency effect when we change the position of the square metal sheet in the vertical direction of the composited terahertz metamaterial structure. In addition, based on the high-quality factor of Fano resonance response, the proposed bifunctional terahertz metamaterial device has good refractive index sensing sensitivity. These results indicate that our proposed terahertz metamaterial can provide guidance for the design of subsequent multifunctional and integrated metamaterials and optoelectronic devices.

A novel electromagnetically induced transparency (EIT) effect analogue based on metamaterials is proposed, which is composed of metal-based H shaped cut wires (MH) and parallel cut wires (MPW) on F4BM substrate. Distinct EIT-like window can be observed under irradiation of plane wave with y polarised direction through the coupling of bright element MH and dark element MPW. In addition, relative position of MH and MPW can influence the EIT-like effect which can be validated by experimental test and expressed by damping rate of bright mode and coupling coefficient of bright-dark mode on the basis of two particles mode. The work exhibits guiding function in EIT designs and realizations.

We study the phenomenon of the electromagnetically induced transparency in planar and stacked plasmonic metamaterials (MMs) using the finite integration time domain and finite element methods. For such structures, the dependence of the tunability of the inherent structural resonances on geometry design is clarified. We also analyze the performance of recently demonstrated MM designs in terms of the achievable group refractive index and losses, which are of great interest for slowing light applications.

In this paper, the author studies, through numerical simulation, the classical analog of the electromagnetically induced absorption/re∞ection (EIA) in a planar metamaterial structure in the near infrared spectral region. The structure is designed by transforming an electromagnetically induced transparency (EIT) structure into an EIA structure using Babinet's principle. The structure exhibits a coupling between a bright mode (a complementary ring resonator (CRR)) and a dark mode (pair of parallel straight slits) imprinted on a glass substrate. A narrow absorption window, induced in a wide transparent window, is achieved by the structure and the strength of coupling is tuned by the degree of breaking symmetry and relative displacement of the two mode elements. Electromagnetically induced transparency (EIT) is a quantum mechanical phenomenon in which an absorption is transformed into a transparency, and this is associated with strong dispersion that reduces the group velocity (1{3). This phenomena has many potential applications in signal processing, optical flltering and sensing technologies (4{7). The classical analog of the EIT has been achieved and reported by many researchers using a planar metamaterial structures that are generally composed of two metallic elements imprinted on a dielectric substrate. The two elements are metallic resonators that act either as two bright modes or a bright and dark mode. A bright mode element couples strongly with the incident excitation fleld while the dark element does not couple with the incident fleld but couples with the magnetic fleld induced by the bright element. Several EIT metamaterial structures have been employed and reported in the microwave, terahertz and optical frequency regions (8{14). In this paper, we propose a new EIT structure that achieves a more pronounced narrow transparency window sandwiched between two absorption bands compared with a similar structure proposed in (14). Also compared with (14), the structure proposed here is independent of the polarization orientation with respect to the bright mode element. Then we transform this structure into an EIA structure using Babinet's principle (15,16), where a narrow absorption/re∞ection window is sandwiched between two transparency bands. The structures proposed here may be used as obscurant particles that allow the passage of a speciflc window/windows of the electromagnetic spectrum and obscure the neighboring frequencies, for this reason the transmission spectrum will be discussed and addressed for the potential obscurant applications. Although the orientational average response of the structure is what matters, it is of good beneflt to get the behavior in a given orientation. The EIT structure is composed of a metallic ring resonator (RR) which acts as a bright mode and a pair of metallic rods that act as a dark mode. Here we overlap the RR wide antenna resonance and the narrow line width quadrupole rod resonance, which in turn produces the EIT-like efiect. The structure is transformed into an EIA structure by replacing the metallic RR and the pair of rods resonator with complementary ring resonator (CRR) and

Electromagnetically Induced Transparency and optical pumping processes formed in Cs sub-micron thin cell

Multifunctional active terahertz metasurface with electromagnetically induced transparency, perfect absorption, and circular dichroism

We propose a scheme to realize stable linear and nonlinear propagation of symmetric and antisymmetric surface plasmon polaritons (SPPs) solitons by doping ladder-type three-level quantum emitters into the middle layer of a metal-dielectric-metal (MDM) waveguide. In linear propagation regime, we show that both symmetric and antisymmetric SPPs can acquire a gain from electromagnetically induced transparency (EIT) effect with an incoherent pumping. The EIT can be used not only to completely compensate the Ohmic loss in the metal but also to acquire a subluminal group velocity for the SPPs. We also show that in nonlinear propagation regime a huge enhancement of Kerr nonlinearity of the symmetric and antisymmetric SPPs can be obtained but with different incoherent pumping intensities. As a result, gain-assisted (1+1)-dimensional symmetric and antisymmetric subluminal surface polaritonic solitons may be produced based on the strong confinement of electric field in the MDM waveguide. Our study may have promising applications in light information processing and transmission at nanoscale level based on MDM waveguides.

Here we experimentally demonstrated the electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) effects in mechanical coupled pendulums. The analogue of EIT and ATS has been studied in mechanical systems and the intrinsic physics between these two phenomena are also been discussed. Exploiting the Akaike Information Criterion, we discern the ATS effect from EIT effect in our experimental results.

As terahertz (THz) technology rapidly develops, room temperature THz detectors with high sensitivity and wide bandwidth are urgently required. Rydberg atoms are very sensitive to external electric fields, and offer a promising approach for THz detection with exceptional sensitivity. In this paper, we propose a method for measuring the THz field with the frequency of 0.17 THz using 85Rb Rydberg atoms. By analyzing the probe laser transmission spectrum and atomic population, the electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting effect are explained by the presence and splitting of the Rydberg dark states; the THz field, coupling laser and probe laser play a crucial role in the EIT signal; and the EIT spectral transmission will increase when the atomic population of the excited state decreases. Moreover, a method was demonstrated to improve the THz detection sensitivity by changing the eigenfrequencies of the Rydberg dark states with THz detuning. This work finds the relationship between EIT-AT effect and atomic population of Rydberg atoms caused by THz wave and provides what we believe to be a new method to improve the detection efficiency.

Electromagnetically induced transparency is a phenomenon that drastically alters light-matter interactions such that an optically opaque medium becomes transparent. To date, it is widely accepted that broken symmetry is a necessary and sufficient condition for the realization of electromagnetically induced transparency (EIT) in nano-plasmonic structures. We have confirmed that even without broken symmetry, the plasmonically induced transparency (PIT) effect based on excitation of magnetic plasmon resonance can be created. We also demonstrated that in general, in the system allowing for higher-order mode excitation, broken symmetry may not be a sufficient condition for the realization of the EIT, in that the EIT may disappear even if the symmetry is broken.