Showing papers on "Electromagnetically induced transparency published in 2017"
TL;DR: In this article, a broad range of resonant electromagnetic effects by using two effective coupled oscillators, including the Fano resonance, electromagnetically induced transparency, Kerker and Borrmann effects, and parity-time symmetry breaking, are reviewed.
Abstract: The importance of the Fano resonance concept is recognized across multiple fields of physics. In this Review, Fano resonance is explored in the context of optics, with particular emphasis on dielectric nanostructures and metasurfaces. Rapid progress in photonics and nanotechnology brings many examples of resonant optical phenomena associated with the physics of Fano resonances, with applications in optical switching and sensing. For successful design of photonic devices, it is important to gain deep insight into different resonant phenomena and understand their connection. Here, we review a broad range of resonant electromagnetic effects by using two effective coupled oscillators, including the Fano resonance, electromagnetically induced transparency, Kerker and Borrmann effects, and parity–time symmetry breaking. We discuss how to introduce the Fano parameter for describing a transition between two seemingly different spectroscopic signatures associated with asymmetric Fano and symmetric Lorentzian shapes. We also review the recent results on Fano resonances in dielectric nanostructures and metasurfaces.
1,234 citations
TL;DR: In this article, the authors review the principle and recent development of EIT in optical microcavities and focus on the following three situations: coupled-cavity system, all-optical EIT appears when the optical modes in different cavities couple to each other.
Abstract: Abstract Electromagnetically induced transparency (EIT) is a quantum interference effect arising from different transition pathways of optical fields. Within the transparency window, both absorption and dispersion properties strongly change, which results in extensive applications such as slow light and optical storage. Due to the ultrahigh quality factors, massive production on a chip and convenient all-optical control, optical microcavities provide an ideal platform for realizing EIT. Here we review the principle and recent development of EIT in optical microcavities. We focus on the following three situations. First, for a coupled-cavity system, all-optical EIT appears when the optical modes in different cavities couple to each other. Second, in a single microcavity, all-optical EIT is created when interference happens between two optical modes. Moreover, the mechanical oscillation of the microcavity leads to optomechanically induced transparency. Then the applications of EIT effect in microcavity systems are discussed, including light delay and storage, sensing, and field enhancement. A summary is then given in the final part of the paper.
159 citations
TL;DR: In this paper, the relationship between the Rabi frequency (ΩRF) related to the applied electric field and Autler-Townes (AT) splitting, when performing atom-based radiofrequency (RF) electric (E) field strength measurements using Rydberg states and electromagnetically induced transparency (EIT) in an atomic vapor, was investigated.
Abstract: We investigate the relationship between the Rabi frequency (ΩRF, related to the applied electric field) and Autler-Townes (AT) splitting, when performing atom-based radio-frequency (RF) electric (E) field strength measurements using Rydberg states and electromagnetically induced transparency (EIT) in an atomic vapor. The AT splitting satisfies, under certain conditions, a well-defined linear relationship with the applied RF field amplitude. The EIT/AT-based E-field measurement approach derived from these principles is currently being investigated by several groups around the world as a means to develop a new SI-traceable RF E-field measurement technique. We establish conditions under which the measured AT-splitting is an approximately linear function of the RF electric field. A quantitative description of systematic deviations from the linear relationship is key to exploiting EIT/AT-based atomic-vapor spectroscopy for SI-traceable field measurement. We show that the linear relationship is valid and can be...
141 citations
TL;DR: In this paper, the optical response of atoms and other quantum emitters coupled to one-dimensional photonic structures, such as cavities, waveguides, and photonic crystals, is studied based on a formalism that describes atomlight interactions in terms of the classical electromagnetic Green's function.
Abstract: Based on a formalism that describes atom-light interactions in terms of the classical electromagnetic Green's function, we study the optical response of atoms and other quantum emitters coupled to one-dimensional photonic structures, such as cavities, waveguides, and photonic crystals. We demonstrate a clear mapping between the transmission spectra and the local Green's function, identifying signatures of dispersive and dissipative interactions between atoms. We also demonstrate the applicability of our analysis to problems involving three-level atoms, such as electromagnetically induced transparency. Finally we examine recent experiments, and anticipate future observations of atom-atom interactions in photonic band gaps.
133 citations
TL;DR: Electromagnetically induced transparency (EIT) is a promising technology for the enhancement of light-matter interactions, and recent demonstrations of the EIT analogue realized in artificial micro-structured medium have remarkably reduced the extreme requirement for experimental observation of EIT spectrum.
Abstract: Electromagnetically induced transparency (EIT) is a promising technology for the enhancement of light-matter interactions, and recent demonstrations of the EIT analogue realized in artificial micro-structured medium have remarkably reduced the extreme requirement for experimental observation of EIT spectrum. In this paper, we propose to electrically control the EIT-like spectrum in a metamaterial as an electromagnetic modulator. A diode acting as a tunable resistor is loaded in the gap of paired wires to inductively tune the magnetic resonance, which induces remarkable modulation on the EIT-like spectrum through the metamaterial sample. The experimental measurements confirmed that the prediction of electromagnetic modulation in three narrow bands on the EIT-like spectrum, and a modulation contrast of up to 31 dB was achieved on the transmission through the metamaterial. Our results may facilitate the study on active/dynamical technology in translational metamaterials, which connect extraordinary manipulations on the flow of light in metamaterials, e.g., the exotic EIT, and practical applications in industry.
111 citations
TL;DR: In this article, a numerical and theoretical study is presented on the realization of the tunable plasmon-induced transparency (PIT) effect in Dirac semimetal films (DSFs) that are known as three-dimensional graphene.
Abstract: A numerical and theoretical study is presented on the realization of the tunable plasmon-induced transparency (PIT) effect in Dirac semimetal films (DSFs) that are known as “three-dimensional graphene”. The weak hybridization between the two parallel bright modes leads to the novel PIT optical response. The properties of the PIT system can be controlled by adjusting the geometric parameters of the DSF strips. Meanwhile, the resonant frequency of the PIT can be dynamically tuned by varying the Fermi energy of the DSFs instead of refabricating the structures. Correspondingly, by adjusting the Fermi energy of the DSFs, a large group delay of more than 1.86 ps is obtained in the vicinity of the transparency peaks. Such proposed DSFs-based PIT system may open up avenues for tunable terahertz switching, slow-light devices, sensing technology and some other THz devices.
109 citations
TL;DR: In this article, the authors investigate the electrically controlled light propagation in the metal-dielectric-metal plasmonic waveguide with a sandwiched graphene monolayer and show that the propagation loss exhibits an obvious peak when the permittivity of graphene approaches an epsilon-near-zero point when adjusting the gate voltage on graphene.
Abstract: We investigate the electrically controlled light propagation in the metal–dielectric–metal plasmonic waveguide with a sandwiched graphene monolayer. The theoretical and simulation results show that the propagation loss exhibits an obvious peak when the permittivity of graphene approaches an epsilon-near-zero point when adjusting the gate voltage on graphene. The analog of electromagnetically induced transparency (EIT) can be generated by introducing side-coupled stubs into the waveguide. Based on the EIT-like effect, the hybrid plasmonic waveguide with a length of only 1.5 μm can work as a modulator with an extinction ratio of ∼15.8 dB, which is 2.3 times larger than the case without the stubs. The active modulation of surface plasmon polariton propagation can be further improved by tuning the carrier mobility of graphene. The graphene-supported plasmonic waveguide system could find applications for the nanoscale manipulation of light and chip-integrated modulation.
107 citations
TL;DR: In this article, a robust coupled oscillator model is proposed to explain the coupling mechanism in the proposed design, which shows a good agreement with the observed results on tunable broadband transparency effect.
Abstract: Electromagnetically induced transparency (EIT) arises from coupling between the bright and dark mode resonances that typically involve subwavelength structures with broken symmetry, which results in an extremely sharp transparency band. Here, we demonstrate a tunable broadband EIT effect in a symmetry preserved metamaterial structure at the terahertz frequencies. Alongside, we also envisage a photo-active EIT effect in a hybrid metal-semiconductor metamaterial, where the transparency window can be dynamically switched by shining near-infrared light beam. A robust coupled oscillator model explains the coupling mechanism in the proposed design, which shows a good agreement with the observed results on tunable broadband transparency effect. Such active, switchable, and broadband metadevices could have applications in delay bandwidth management, terahertz filtering, and slow light effects.
94 citations
TL;DR: This paper shows that the obstacles to achieve high Q-factor can be effectively suppressed by using dielectric nanodisk arrays, where the Q-Factor is about one order larger than that of the single disks associated with the nonradiating anapole modes and the collective oscillations of the arrays.
Abstract: The simultaneous realization of high Q-factor resonances and strong near-field enhancements around and inside of dielectric nanostructures is important for many applications in nanophotonics. However, the incident fields are often confined within dielectric nanoparticles, which results in poor optical interactions with external environment. Near-field enhancements can be extended outside of dielectric nanostructures with proper design, but the Q-factor is often reduced caused by additional radiation losses. This paper shows that the obstacles to achieve high Q-factor, that is, the radiative losses can be effectively suppressed by using dielectric nanodisk arrays, where the Q-factor is about one order larger than that of the single disks associated with the nonradiating anapole modes and the collective oscillations of the arrays. When the resonance energies of the electric dipole mode and the subradiant mode are degenerate with each other, the destructive interference produces an effect analogous to electromagnetically induced transparency. Furthermore, the Q-factor can be extremely enlarged with dielectric split nanodisk arrays, where the present of the split gap does not induce additional losses. Instead, the coupling between the two interfering modes is modified by adjusting the gap width, which makes it possible to achieve high Q-factor and strong near-field enhancements around and inside of the split disks simultaneously. It is shown that the Q-factor is approaching to 106 when the gap width is about 110 nm, and the near-field enhancements around and inside of the split disks are about two orders stronger than that of the single disk.
92 citations
TL;DR: A terahertz electromagnetically induced transparency (EIT) metamaterial, consisting of single-layer graphene cut wire resonator arrays with closely placed graphene closed ring resonator array, was designed and numerically investigated in this paper.
92 citations
TL;DR: Details of the physical principle and theory of quantum memory based specifically on EIT are provided and important milestones from the first experimental demonstration to current applications in quantum information systems are reviewed.
Abstract: Electromagnetically induced transparency (EIT) is a promising approach to implement quantum memory in quantum communication and quantum computing applications. In this paper, following a brief overview of the main approaches to quantum memory, we provide details of the physical principle and theory of quantum memory based specifically on EIT. We discuss the key technologies for implementing quantum memory based on EIT and review important milestones, from the first experimental demonstration to current applications in quantum information systems.
TL;DR: In this article, the authors employ the phenomena of electromagnetically induced transparency (EIT) and Autler-Townes splitting to measure the electric field strength (V/m) in the near field.
Abstract: We discuss a fundamentally new method for electric (E) field strength (V/m) metrology applicable to the near-field. This new approach is significantly different from currently used field measurement techniques in that it is based on the interaction of radio-frequency (RF) E-fields with Rydberg atoms (alkali atoms placed in a glass vapor cell that are excited optically to Rydberg states). The applied RF E-field alters the state of the atoms. The Rydberg atoms act like an RF-to-optical transducer, converting an RF E-field strength to an optical-frequency response. In this new approach, we employ the phenomena of electromagnetically induced transparency (EIT) and Autler-Townes splitting. The RF transition in the four-level atomic system causes a split of the EIT transmission spectrum of a probe laser into two peaks. This splitting is easily measured and is directly proportional to the applied RF E-field amplitude. The significant dipole response of Rydberg atoms enables this technique to make self-calibrating measurements over a large frequency band including 500 MHz to 500 GHz (and possibly up to 1 THz and down to 10s of megahertz). In this paper, we report on our results in the development of this metrology approach, including the first fiber-coupled vapor-cell for E-field measurements. We also discuss key applications, including self-calibrated measurements, millimeter-wave and sub-THz measurements, field mapping, and sub-wavelength and near-field imaging. We show results for mapping the fields inside vapor cells, for measuring the E-field distribution along the surface of a circuit board, and for measuring the near-field at the aperture in a cavity. We also discuss the uncertainties of this measurement technique.
TL;DR: In this article, the authors demonstrated a low-loss and high-transmission analogy of electromagnetically induced transparency based on all-dieletric metasurface.
Abstract: In this paper, we demonstrated a low-loss and high-transmission analogy of electromagnetically induced transparency based on all-dieletric metasurface. The metamaterial unit cell structure is composed of two mutually perpendicular silicon nanoscale bars. Under the joint effects of the neighboring meta-atoms’ coherent interaction and significant low absorption loss, the transmission and the Q-factor can reach up to 93 % and 139, respectively. Moreover, we use the coupled harmonic oscillator model to analyze the near field interaction between the two elements in the electromagnetically induced transparency (EIT) metamaterial unit cell qualitatively and the effects of parameters on EIT. The figure-of-merit of 42 and the group delay of 0.65 ps are obtained. These characteristics make the metamaterial structure with potential to apply for ultrafast switches, sensor, and slow-light devices.
TL;DR: A suitable theoretical model is established to study spectral features in the plasmonic graphene system, and the theoretical results agree well with the simulations, and may provide guidance for fundamental research of highly tunable optoelectronic devices.
Abstract: A graphene plasmonic structure consists of three graphene layers mingled with a silicon–air grating is proposed. We theoretically predict and numerically simulate the plasmon-induced transparency effect in this system at terahertz wavelengths, and a dual plasmon-induced transparency peaks can be successfully tuned by virtually shifting the desired Fermi energy on graphene layers. We investigate the surface plasmon dispersion relation by means of analytic calculations, and we can achieve the numerical solution of propagation constant got by the dispersion relation. A suitable theoretical model is established to study spectral features in the plasmonic graphene system, and the theoretical results agree well with the simulations. The proposed model and findings may provide guidance for fundamental research of highly tunable optoelectronic devices.
TL;DR: An experiment demonstrating the generation of directional thermal radiation with a spectral brightness that is about 9 times greater than that of the ambient pumping reservoir is reported.
Abstract: We report an experiment demonstrating the generation of directional thermal radiation with a spectral brightness that is about 9 times greater than that of the ambient pumping reservoir. The experiment is based on the recent proposal for a nontraditional quantum heat engine and uses cold Rb atoms, electromagnetically induced transparency, and photon correlation spectroscopy [Phys. Rev. A 94, 053859 (2016)PLRAAN2469-992610.1103/PhysRevA.94.053859].
TL;DR: The PIT effect is explored in a metamaterial comprising of a cross like structure and four C-shaped resonators, and it is observed that such a structure exhibits equally strong PIT effects for both the incident polarizations, indicating a polarization independent response to the incident terahertz radiation.
Abstract: We analyze plasmon induced transparency (PIT) in a planar terahertz metamaterial comprising of two C-shaped resonators and a cut-wire. The two C-shaped resonators are placed alternately on both sides of the cut-wire such that it exhibits a PIT effect when coupled with the cut wire. We have further shown that the PIT window is modulated by displacing the C-shaped resonators w.r.t. the cut-wire. A lumped element equivalent circuit model is reported to explain the numerical observations for different coupling configurations. The PIT effect is further explored in a metamaterial comprising of a cross like structure and four C-shaped resonators. For this configuration, the PIT effect is studied for the incident light polarized in both x and y directions. It is observed that such a structure exhibits equally strong PIT effects for both the incident polarizations, indicating a polarization independent response to the incident terahertz radiation. Our study could be significant in the development of slow light devices and polarization independent sensing applications.
TL;DR: In this article, the authors show that the Autler-Townes splitting (ATS) phenomenon can be used for coherent storage and manipulation of light with matter in the ATS regime, which is suitable for efficient broadband quantum memory and processing devices.
Abstract: The coherent control of light with matter, enabling storage and manipulation of optical signals, was revolutionized by electromagnetically induced transparency (EIT), which is a quantum interference effect. For strong electromagnetic fields that induce a wide transparency band, this quantum interference vanishes, giving rise to the well-known phenomenon of Autler-Townes splitting (ATS). To date, it is an open question whether ATS can be directly leveraged for coherent control as more than just a case of "bad" EIT. Here, we establish a protocol showing that dynamically controlled absorption of light in the ATS regime mediates coherent storage and manipulation that is inherently suitable for efficient broadband quantum memory and processing devices. We experimentally demonstrate this protocol by storing and manipulating nanoseconds-long optical pulses through a collective spin state of laser-cooled Rb atoms for up to a microsecond. Furthermore, we show that our approach substantially relaxes the technical requirements intrinsic to established memory schemes, rendering it suitable for broad range of platforms with applications to quantum information processing, high-precision spectroscopy, and metrology.
TL;DR: In this article, a new graphene-based metamaterial biosensor was proposed to achieve tunable plasmon-induced transparency in the mid-infrared (mid-IR) regime.
Abstract: We propose a new graphene-based metamaterial biosensor to achieve tunable plasmon-induced transparency in the mid-infrared (mid-IR) regime. The structure consists of a graphene sheet with three cut-out strips that has been located on a substrate. It is shown that the plasmonically induced transparency (PIT) can be realized by breaking the symmetry of the structure in the normal incidence and also changing the polarization of the incident light in the symmetric case. By optimizing the physical parameters of the antennas, an extremely strong optical sensing coefficient (about 99%) is observed in the mid-IR frequency range based on the PIT effect, which is much larger than that of related previous studies. More importantly, we observed a blueshift in the transparency window through the increase of the gate voltage of the graphene’s chemical potential. The transparency window strongly depends on the physical parameters of the substrate and filling material. Furthermore, it is found that the biosensing application of the proposed structure is highly dependent on inserting an ultra-thin buffer layer between the graphene and substrate layer, leading to a tunable PIT in the mid-IR regime.
TL;DR: 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.
Abstract: 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.
TL;DR: It is demonstrated that an ultrathin water-based metasurface capable of coherent perfect absorption (CPA) at radio frequencies can almost completely absorb two symmetrically incident waves within four frequency bands, each having its own modulation depth of metAsurface absorptivity.
Abstract: We design an ultrathin water-based metasurface capable of coherent perfect absorption (CPA) at radio frequencies. It is demonstrated that such a metasurface can almost completely absorb two symmetrically incident waves within four frequency bands, each having its own modulation depth of metasurface absorptivity. Specifically, the absorptivity at 557.2 MHz can be changed between 0.59% and 99.99% via the adjustment of the phase difference between the waves. The high angular tolerance of our metasurface is shown to enable strong CPA at oblique incidence, with the CPA frequency almost independent of the incident angle for TE waves and varying from 557.2 up to 584.2 MHz for TM waves. One can also reduce this frequency from 712.0 to 493.3 MHz while retaining strong coherent absorption by varying the water layer thickness. It is also show that the coherent absorption performance can be flexibly controlled by adjusting the temperature of water. The proposed metasurface is low-cost, biocompatible, and useful for electromagnetic modulation and switching.
TL;DR: A plasmonic refractive index sensor based on electromagnetically induced transparency (EIT) composed of a metal-insulator-metal (MIM) waveguide with stub resonators and a ring resonator is presented in this article.
Abstract: A plasmonic refractive index sensor based on electromagnetically induced transparency (EIT) composed of a metal-insulator-metal (MIM) waveguide with stub resonators and a ring resonator is presented. The transmission properties and the refractive index sensitivity are numerically studied with the finite element method (FEM). The results revealed an EIT-like transmission spectrum with an asymmetric line profile and a refractive index sensitivity of 1057 nm/RIU are obtained. The coupled mode theory (CMT) based on transmission line theory is adopted to illustrate the EIT-like phenomenon. Multiple EIT-like peaks are observed in the transmission spectrum of the derived structures based on the MIM waveguide with stub resonator coupled ring resonator. To analyze the multiple EIT-like modes of the derived structures, the H
z field distribution is calculated. In addition, the effect of the structural parameters on the EIT-like effect is also studied. These results provide a new method for the dynamic control of light in the nanoscale.
TL;DR: A tunable dual-band plasmonically induced transparency (PIT) device based on hybrid metal-graphene nanostructures is proposed theoretically and numerically at mid-infrared frequencies, which is composed of two kinds of gold dolmen-like structures placed on separate graphene interdigitated finger sets respectively.
Abstract: A tunable dual-band plasmonically induced transparency (PIT) device based on hybrid metal-graphene nanostructures is proposed theoretically and numerically at mid-infrared frequencies, which is composed of two kinds of gold dolmen-like structures with different sizes placed on separate graphene interdigitated finger sets respectively. The coupled Lorentz oscillator model is used to explain the physical mechanism of the PIT effect at multiple frequency domains. The finite-difference time-domain (FDTD) solutions are employed to simulate the characteristics of the hybrid metal-graphene dual-band PIT device. The simulated spectral locations of multiple transparency peaks are separately and dynamically modulated by varying the Fermi energy of corresponding graphene finger set, which is in good accordance with the theoretical analysis. Distinguished from the conventional metallic PIT devices, multiple PIT resonances in the hybrid metal-graphene PIT device are independently modulated by electrostatically changing bias voltages applied on corresponding graphene fingers, which can be widely applied in optical information processing as tunable sensors, switches, and filters.
TL;DR: This approach separates the single-polariton EIT physics from Rydberg-Rydberg interactions in a serialized manner while using a hard-sphere model for the latter, thus capturing the dualistic particle-wave nature of light as it manifests itself in dissipative Ryd Berg-EIT media.
Abstract: Rydberg blockade physics in optically dense atomic media under the conditions of electromagnetically induced transparency (EIT) leads to strong dissipative interactions between single photons. We introduce a new approach to analyzing this challenging many-body problem in the limit of a large optical depth per blockade radius. In our approach, we separate the single-polariton EIT physics from Rydberg-Rydberg interactions in a serialized manner while using a hard-sphere model for the latter, thus capturing the dualistic particle-wave nature of light as it manifests itself in dissipative Rydberg-EIT media. Using this approach, we analyze the saturation behavior of the transmission through one-dimensional Rydberg-EIT media in the regime of nonperturbative dissipative interactions relevant to current experiments. Our model is able to capture the many-body dynamics of bright, coherent pulses through these strongly interacting media. We compare our model with available experimental data in this regime and find good agreement. We also analyze a scheme for generating regular trains of single photons from continuous-wave input and derive its scaling behavior in the presence of imperfect single-photon EIT.
TL;DR: In this article, a 3D planar nano-structure metamaterial exhibiting classical electromagnetically induced transparency (Cl-EIT) was proposed and the interaction between two different plasmonic modes of the unit cell, induced directly or indirectly by the incident electromagnetic wave, leads to a transparent window, resembling the Cl- EIT.
Abstract: We report on our numerical work concerning a 3D planar nano-structure metamaterial exhibiting classical electromagnetically induced transparency (Cl-EIT). The interaction between two different plasmonic modes of the unit cell, induced directly or indirectly by the incident electromagnetic wave, leads to a transparent window, resembling the Cl-EIT. Their interactions and coupling between plasmonic modes are investigated in detail by analyzing magnetic field distributions and spectral responses. Simply by introducing of symmetry broken of the proposed nano-structure, the Cl-EIT can be dynamically tuned. At one special asymmetric case, a sharp transparency window with the bandwidth of about 2.96 nm (corresponding to 0.6 THz in frequency regime) is obtained at 246.3 THz (corresponding to 1.218 μm). The corresponding quality factor (Q-factor) is 411. Also, we show that the Cl-EIT frequency position depended very sensitively on the used metal in the metamaterial. Furthermore, we demonstrate numerically that tunable slow light can be realized in our planar nano-structure metamaterial with the unit cell composed of dark and bright plasmonic modes in a broad terahertz regime. It is demonstrated that the increased Q-factor leads to large group index (of the order of 620), which is promising for efficient plasmonic sensing, optical switching, and slow-light devices design.
TL;DR: In this paper, a classical analogue of electromagnetically induced transparency (EIT) metamaterial is numerically and experimentally demonstrated, where the unit cell of the proposed structure is composed of two identical and orthogonal double-end fork (DEF) metallic resonators.
Abstract: In this paper, a classical analogue of electromagnetically induced transparency (EIT) metamaterial is numerically and experimentally demonstrated. The unit cell of our proposed structure is composed of two identical and orthogonal double-end fork (DEF) metallic resonators. Under the excitation of the normally incident waves, each of the two DEFs exhibits different frequency of electric dipole response, which leads to the ultra-broadband and polarization-independent EIT-like effect. The resonant feature of the EIT-like effect has been qualitatively analyzed from the surface current distributions and quantitatively by the “two-oscillator” coupling model. In addition, the large group index is extracted to verify the slow light property within the transmission window. The EIT metamaterial structure with the above-mentioned characteristics may have potential applications in some areas, such as sensing, slow light, and filtering devices.
TL;DR: In this paper, a Doppler-broadened hot rubidium atomic vapor cell was used to generate biphotons with spectral brightness as high as 14'000's−1'1'MHz−1.
Abstract: We demonstrate the generation of high-quality narrowband biphotons from a Doppler-broadened hot rubidium atomic vapor cell. Choosing a double-Λ atomic energy level scheme for optimizing both spontaneous four-wave mixing nonlinear parametric interaction and electromagnetically induced transparency (EIT), we achieve a biphoton spectral brightness as high as 14 000 s−1 MHz−1. Meanwhile, we apply a spatially tailored optical pumping beam for reduction of the Raman noise and obtain a violation of the Cauchy-Schwarz inequality by a factor of 1023.
TL;DR: An on-chip coupling resonant system to generate electromagnetically induced transparency (EIT)-like effect and Fano resonance on silicon platform and results show Fano resonances with maximum extinction ratio (ER) of 23.22 dB and maximum slope rate (SR) of 252 dB/nm.
Abstract: We propose and demonstrate an on-chip coupling resonant system to generate electromagnetically induced transparency (EIT)-like effect and Fano resonance on silicon platform. It is composed of a microring resonator (MRR) and two cascaded Sagnac-loop mirrors (SLMs) assisted Fabry-Perot (FP) cavity on silicon-on-insulator. According to the coupling conditions of the MRR, two cases are studied theoretically. When the MRR is over coupling, EIT-like transmission can be observed. In contrast, Fano resonances can be generated by the condition of under coupling. In the experiment, the add-drop MRR is under coupling, leading to a sharp asymmetric line shape for Fano resonance. The resonance wavelength of the MRR can be dynamically tuned based on thermal-optic effects by tuning the micro-heater. The experiment results show Fano resonances with maximum extinction ratio (ER) of 23.22 dB and maximum slope rate (SR) of 252 dB/nm. Moreover, the wavelength of Fano resonance can be shifted widely with a tuning efficiency of 0.2335 nm/mW.
TL;DR: In this paper, a hyperbolic metamaterial (HMM) was used to convert the near fields into high-k propagating waves to overcome the problem of weak coupling at long distance.
Abstract: Near-field coupling is a fundamental physical effect, which plays an important role in the establishment of classical analog of electromagnetically induced transparency (EIT). However, in a normal environment the coupling length between the bright and dark artificial atoms is very short and far less than one wavelength, owing to the exponentially decaying property of near fields. In this work, we report the realization of a long range EIT, by using a hyperbolic metamaterial (HMM) which can convert the near fields into high-k propagating waves to overcome the problem of weak coupling at long distance. Both simulation and experiment show that the coupling length can be enhanced by nearly two orders of magnitude with the aid of a HMM. This long range EIT might be very useful in a variety of applications including sensors, detectors, switch, long-range energy transfer, etc.
TL;DR: In this paper, the authors proposed a novel beamforming scheme based on three vertically placed split ring resonators (SRRs) working at terahertz frequencies, with a typical EIT-like transmission, couples to both the electric and magnetic fields of the normally incident wave.
Abstract: Plasmon-induced transparency (PIT) is a key addition to mimicking the quantum phenomena of electromagnetically induced transparency (EIT) in atomic systems. So far, various metamaterial structures have been proposed to excite and manipulate the PIT effect. However, most of the reported works were based on 2-D metal structures, and consequently, the PIT phenomena often arise from their electric responses. Here, we propose a novel PIT metamaterial scheme based on three vertically placed split ring resonators (SRRs) working at terahertz frequencies. This stereo structure, with a typical EIT-like transmission, couples to both the electric and magnetic fields of the normally incident wave. We numerically demonstrate that the coupling between the radiative and subradiative elements can be modulated not only by their mutual separation but also by the vertical height of the SRRs. In addition, a classical Fano resonance model is applied to explain the coupling effects of EIT-like transmission spectra, which is in good accordance with the numerical results. Considering the higher design freedom of the stereo metamaterials, our work provides a promising way for PIT metamaterial and terahertz slow light device research.
TL;DR: In this article, a dynamically tunable electromagnetically induced transparency (EIT) system consisting of two coupled micro-ring resonators, one of which is embedded with a graphene layer, is proposed and numerically demonstrated.
Abstract: A dynamically tunable electromagnetically induced transparency (EIT) system consisting of two coupled micro-ring resonators, one of which is embedded with a graphene layer, is proposed and numerically demonstrated. The effective refractive index of the graphene-based micro-ring resonator can be significantly tuned by varying the gate voltage applied on graphene, inducing significant modulation of the resonant wavelength of EIT transparency window over a wide spectral bandwidth. Typical tunability of the EIT resonance is approximately 1.62 nm/V around 1550 nm, which is much better than that based on a nanoelectromechanical EIT system. Such a configuration implies the possibility of constructing various optical devices toward realization of photon pulse trapping, optical modulation, and filtering on a chip.