Induced Transparency Resonance Research Articles

Stretchable kirigami mechanical metamaterial with tunable dual electromagnetically induced transparency resonances

Kirigami, i.e. paper cutting is nowadays widely investigated to design the mechanical structure that can be transformed with unique and programmable performances. When it is transformed, the components of the kirigami are also reconfigured and then provide tunable polarization-sensitive electromagnetic responses. In this study, we present a design of stretchable kirigami mechanical metamaterial (SKMM) with dual electromagnetically induced transparency (EIT) resonances. The proposed two designs of SKMM show two dual EIT resonances at 0.905 THz, 0.975 THz, and 0.449 THz, 0.558 THz, which can be switched to 0.964 THz, 1.042 THz and 0.433 THz, 0.532 THz by rotating kirigami cells in predestinated orientations, respectively. During the continuous modulations of transmission spectra by increasing the stretching force, the characteristics of resonant spectra maintain excellent with their corresponding averaged Q-factors as 33.19, 21.59 and 4.87, 17.31, respectively. The EIT resonances originating from the bright-bright mode could be explained with multipole scattering theory along with the three-dimensional schematic illustrations. These results prove the proposed SKMM possesses promising applications in slow light, optical data computing, quantum information technology, and sensing fields.

Impact of higher-order laguerre-gaussian modes on electromagnetically induced transparency resonances in $$^{87}$$Rb atomic vapor medium

Impact of higher-order laguerre-gaussian modes on electromagnetically induced transparency resonances in $$^{87}$$Rb atomic vapor medium

Electrically Injected Metamaterial Grating DFB Laser Exploiting an Ultra‐High Q Electromagnetic Induced Transparency Resonance for Spectral Selection

AbstractThe study shows that, in waveguide (WG) configuration, the coupling of a 2D plasmonic metamaterial grating (MMG) having a conventional Bragg period along the guide but a distinct period along the transverse axis can lead to Electromagnetically‐Induced‐Transparency (EIT) behavior. This epitomizes that metamaterials, as functional photonic building blocks, can lead to low losses in many standard devices if properly designed. The study reported the observation in passive WGs of a marked Fano‐type EIT resonance with record high‐quality factor: Q = 5000 and contrast >20 dB. Unlike any standard metal grating, MMG‐assisted waveguides exhibit strong grating coupling strength and low‐loss properties simultaneously. This concept is further applied to demonstrate single‐frequency‐emission electrically‐injected Distributed Feedback (DFB) lasers in the near‐infrared telecom domain. The key point is that laser emission occurs at the peak of EIT, i.e., the maximum in transmission. It therefore addresses one of the main critical issues of DFB lasers related to the single frequency yield. The laser performances are state‐of‐the‐art (Ith < 20 mA, Pmax > 20 mW at I = 200 mA, SMSR > 50 dB, optical feedback tolerance >−21 dB compliant with IEEE 802.3 standard). The presented approach, compatible with existing industrial technologies, is promising for real‐life telecom applications.

Metamaterials Photonic Filter Based on Electromagnetically Induced Transparency Resonance

Metamaterials Photonic Filter Based on Electromagnetically Induced Transparency Resonance

Coexistence of Fano and electromagnetically induced transparency resonance line shapes in photonic topological insulators

Due to the bending resistance and defect immunity of the topological optical structure, topological photonics is extended to researching Fano line shapes or electromagnetically induced transparency-like (EIT-like) line shapes. In this paper, two-dimensional photonic crystal with Kekule´ distortion is designed to realize quantum spin Hall effect and quantum valley Hall effect simultaneously. The stable topological corner states and edge states are obtained. Corner states as dark modes interfere with edge states as bright mode to induce Fano or EIT-like line shapes. As far as we know, we first realize the coexistence of Fano and EIT-like line shapes based on the coexistence of quantum spin Hall effect and quantum valley Hall effect. Our results provide a new way to realize multi-channel sensing technology.

MAPbI3 perovskite hybrid metasurface for agile, multidimensional THz wave modulation with 3D Dirac semimetal-like Fermi model optically induced by three wavelength bands

Organic–inorganic hybrid three-dimensional (3D) perovskite materials have emerged as potential candidates for terahertz (THz) modulators. In this study, the metasurface of electromagnetically induced transparency resonance was integrated with 3D perovskite to achieve a high-efficiency dynamic THz modulator. The integration was achieved by modulating the intrinsic optoelectronic properties of perovskite with three wavelengths of optical pump and external voltage excitation. The maximum modulation depth was 466.8 %, with a pump flux of 11.5 mW/cm2 and excitation at 532 nm. The Dirac-like semimetal-Fermi energy band model was proposed to explain the dynamic transitions of free carriers in perovskites and reveal the internal mechanism of the dynamic modulation. In addition, we verified our proposed theoretical model by simulation and theoretical fitting, and calculated the conductivity and number of free carriers of perovskite under different excitations. The system thoroughly explains the observed differences under three wavelengths of optical pump excitation. The active control of THz waves based on Dirac semimetal materials with optical and electrical inputs could have many potential applications that have been proposed by few studies.

Y-shaped phononic demultiplexer based on Fano and acoustically induced transparency resonances in one dimensional asymmetric/symmetric loops structure

In this work, we present an analytical demonstration of the possibility to realize a simple phononic demultiplexer based on Fano and Acoustically Induced Transparency (AIT) resonances. The demultiplexer is a Y-shaped waveguide with an input line and two output lines (called also channels). The first output line is composed of a segment (guide) of length d1 and two symmetric/asymmetric loops of lengths d2 and d3, the second output line contains a segment of length d4 and two symmetric/asymmetric loops of lengths d5 and d6. We derive the analytical expressions for a selective transfer of a single propagation mode through one line by keeping the other line unaffected. This AIT resonance is characterized by a maximum transmission peak wedged between two transmission zeros. The existence of a complete transmission beside a transmission zero (Fano resonance) enables the selection of a given frequency in the first output line, by canceling the transmission in the second output line and the reflection in the input line. The position and the quality factor of these resonances are sensitive to the geometrical parameters of the segments and loops which should be chosen appropriately. The effect of the symmetric and asymmetric loops on the transmission spectra of our proposed demultiplexer is also discussed. The theoretical results are obtained out using the continuous medium interface response theory, which makes it possible to calculate the Green function of any composite material. This allows us to determine the two transmission rates T1, T2 and the reflection rate R. This structure can be used as high performance and high transmittance acoustic guiding, demultiplexing and noise filtering.

Molecularization of meta-atoms for electromagnetically induced transparency resonance and quality-factor switching

Electromagnetically induced transparency (EIT) analogs in terahertz regimes have been actively tuned by hybridizing semiconductors into metasurfaces for effective terahertz manipulation. Although several multiple means have been adopted to modulate EIT, the active control of the EIT quality factor is less reported. Multifunctional EIT modulation should also be considered. In this study, we fabricated a terahertz metadevice by embedding Si bridges into a metasurface with optically controllable molecularization of terahertz meta-atoms and experimentally demonstrated dual-functional terahertz EIT modulation, including resonance amplitude modulation and quality-factor modulation. For a low-power pumping of 16 mW, ultrafast EIT resonance amplitude modulation can be achieved with a low-level molecularization, with a normalized amplitude modulation of up to 85%. Then, with a high-power pumping of 360 mW, we performed ultrafast EIT quality-factor switching, where the high Si-bridge conductivity altered the spatial interconnected structure and exhibited high-level molecularization. Both functions have a nanosecond-scale modulation speed. In addition, we numerically and theoretically explained the terahertz modulation and molecularization behaviors, which was consistent with the experimental results. Our proposed all-optical active terahertz metadevice with controllable molecularization provides a novel solution for multifunctional and ultrafast switchable terahertz modulators.

Analytical and numerical study of T-shaped plasmonic demultiplexer based on Fano and induced transparency resonances

We study analytically and numerically the design of plasmonic demultiplexers based on Fano and plasmonic induced transparency (PIT) resonances. The demultiplexers consist of T-shaped structures with an input waveguide and two output waveguides. Each output contains two waveguide stubs grafted either at the same position or at two different positions far from the input waveguide. We derive closed form analytical expressions of the geometrical parameters allowing a selective transfer of a single mode in one waveguide without affecting the other one. This is performed by implementing the Fano and PIT resonances which are characterized by a resonance placed near an antiresonance or placed between two antiresonances respectively. In particular, we show the possibility of trapped modes, also called bound in continuum (BIC) modes. These modes appear as resonances with zero width in the transmission spectra for appropriate lengths of the stubs. Then, by detuning slightly the stubs, BICs transform to PIT or Fano resonances. The existence of a full transmission besides a transmission zero, enables to filter a given wavelength on one output waveguide, by vanishing both the transmission on the second waveguide as well as the reflection in the input waveguide. The demultiplexer is capable to separate two fundamental optical windows (i.e. 1310 and 1550 nm). The performance of the demultiplexer platform is measured using the crosstalk of the two outputs and quality factor. The lowest value of the crosstalk −96.8 dB with an average of −84.7 dB is achieved and a maximum quality factor 45 is obtained. The maximum transmission reaches a high value of 85% despite the large metallic losses. These values are suitable for integrated photonic circuits in the optical communication. The analytical results are obtained by means of the Green’s function method which enables us to deduce the transmission and reflection coefficients, as well as the delay times and density of states. These results are confirmed by numerical simulations using a 2D finite element method. The analytical analysis developed in this work represent a predictive method to understand deeply different physical phenomena in more complex plasmonic devices.

Spatiotemporal Terahertz Metasurfaces for Ultrafast All‐Optical Switching with Electric‐Triggered Bistability

AbstractOptoelectronic terahertz switching achieved by dynamically tuning metamaterials is viewed as a major breakthrough in promoting the advancement of terahertz technology. However, the main thrust toward the development of ultrafast switchable components and optical logic operations is still in a catch‐up stage for progressively increasing information and communication demands. Here, a novel spatiotemporal metadevice is proposed for terahertz wave steering in multidimensional domains with ultrahigh spatial and ultrafast temporal manipulations. By spatially changing the interconnect architecture via the embedded vanadium dioxide bridges, the state of electromagnetically induced transparency resonance is switched between “1” and “0” states under electrical stimuli, exhibiting a typical 1 bit coding bistability with a long retention time. Furthermore, with the characteristic of writable/erasable logic operation, ultrafast photoswitching of each memorized state is manifested by delivering optical excitations. The high‐speed temporal response of terahertz radiation exhibits an on–off–on switching cycle within 16 ps, owing to the defect‐rich germanium photoactive layer. By leveraging both degrees of freedom in space and time domains, this multifunctional spatiotemporal metaphotonic device can upgrade and improve the current capabilities of optical computing, data storage, and ultrahigh‐speed information processing, paving the way for a highly unexplored territory toward manipulations of light.

Acoustic demultiplexer based on Fano and induced transparency resonances in slender tubes

We give an analytical demonstration of the possibility to realize a simple phononic demultiplexer based on Fano and acoustic induced transparency resonances. The demultiplexer consists of a Y-shaped waveguide with an input line and two output lines. Each output line contains two stubs grafted either at a given position or at two positions far from the input line. We derive in closed form the expressions for a selective transfer of a single propagating mode through one line keeping the other line unaffected.

Selective excitation of whispering-gallery modes and Fano resonance in a high-Q micro-capillary resonator with cleaned-up spectrum

We demonstrate, experimentally and theoretically, a micro-capillary resonator with surface nanoscale axial photonics for clean and nearly equidistant spectra, which belongs to a category of bottle-shaped optofluidic ring resonators. Selective excitation for the lowest five axial modes is achieved by changing the gap between the resonator and the taper and the coupling position along the micro-capillary. By scanning tapered fiber diameters carefully, the resonance state for converting a Lorentzian resonance to a Fano resonance and an electromagnetically induced transparency resonance is exhibited. The results obtained pave the way for an enhanced approach in sensing and, in particular, in microfluidic sensing.

A compact structure for realizing Lorentzian, Fano, and electromagnetically induced transparency resonance lineshapes in a microring resonator

Abstract Microring resonators, as a fundamental building block of photonic integrated circuits, are well developed into numerous functional devices, whose performances are strongly determined by microring’s resonance lineshapes. We propose a compact structure to reliably realize Lorentzian, Fano, and electromagnetically induced transparency (EIT) resonance lineshapes in a microring. By simply inserting two air-holes in the side-coupled waveguide of a microring, a Fabry-Perot (FP) resonance is involved to couple with microring’s resonant modes, showing Lorentzian, Fano, and EIT lineshapes over one free spectral range of the FP resonance. The quality factors, extinction ratios (ERs), and slope rates (SRs) in different lineshapes are discussed. At microring’s specific resonant wavelength, the lineshape could be tuned among these three types by controlling the FP cavity’s length. Experiment results verify the theoretical analysis well and represent Fano lineshapes with ERs of about 20 dB and SRs over 280 dB/nm. The reliably and flexibly tunable lineshapes in the compact structure have potentials to improve microring-based devices and expand their application scopes.

Y-shaped magnonic demultiplexer using induced transparency resonances

We give an analytical demonstration of the possibility to realize a simple magnonic demultiplexer based on induced transparency resonances. The demultiplexer consists on an Y-shaped waveguide with an input line and two output lines. Each line contains two grafted stubs at a given position far from the input line. We derive in closed form the analytical expressions for selective transfer of a single propagating mode through one line keeping the other line unaffected. This is performed through magnonic induced transparency resonances (MIT) characterized by a resonance squeezed between two transmission zeros. The existence of a complete transmission beside a zero transmission, enables to select a given frequency on one output line, by canceling the transmission on the second line as well as the reflection in the input line. Also, we show that despite the existence of a bifurcation of the input line on two output lines, the transmission through each line can be written following a Fano line shape. In addition, in order to understand better the scattering properties of the filtered resonances, we give the analytical expressions of Fano parameter q and quality factor Q of the MIT resonance in each line. The spatial distribution of the spin waves associated to different MIT resonances is performed through an analysis of the magnetization of these modes. Also, the effect of attenuation on the transmission spectra and the quality of demultiplexing is also discussed. The theoretical results are performed using the Green’s function approach which enables to deduce in closed form, the transmission and reflection coefficients as well as the densities of states.

Photonic demultiplexer based on electromagnetically induced transparency resonances

We give an analytical and experimental demonstration of the possibility to realize a simple photonic demultiplexer based on electromagnetically induced transparency resonances. The demultiplexer consists of a Y-shaped waveguide with an input line and two output lines. Each output line contains two grafted stubs at a given position far from the input line. We derive in closed form the expressions for a selective transfer of a single propagating mode through one line keeping the other line unaffected. We illustrate the analytical and numerical results by a simple experiment carried out using coaxial cables in the radio frequency domain.

Radio-over-fiber using an optical antenna based on Rydberg states of atoms

We provide an experimental demonstration of a direct fiber-optic link for RF transmission (“radio-over-fiber”) using a sensitive optical antenna based on a rubidium vapor cell. The scheme relies on measuring the transmission of laser light at an electromagnetically induced transparency resonance that involves highly excited Rydberg states. By dressing pairs of Rydberg states using microwave fields that act as local oscillators, we encoded RF signals in the optical frequency domain. The light carrying the information is linked via a virtually lossless optical fiber to a photodetector where the signal is retrieved. We demonstrate a signal bandwidth in excess of 1 MHz limited by the available coupling laser power and atomic optical density. Our sensitive, non-metallic and readily scalable optical antenna for microwaves allows extremely low-levels of optical power (∼1 μW) throughput in the fiber-optic link. It offers a promising future platform for emerging wireless network infrastructures.

Versatile, high-power 460 nm laser system for Rydberg excitation of ultracold potassium.

We present a versatile laser system which provides more than 1.5 W of narrowband light, tunable in the range from 455-463 nm. It consists of a commercial titanium-sapphire laser which is frequency doubled using resonant cavity second harmonic generation and stabilized to an external reference cavity. We demonstrate a wide wavelength tuning range combined with a narrow linewidth and low intensity noise. This laser system is ideally suited for atomic physics experiments such as two-photon excitation of Rydberg states of potassium atoms with principal quantum numbers n > 18. To demonstrate this we perform two-photon spectroscopy on ultracold potassium gases in which we observe an electromagnetically induced transparency resonance corresponding to the 35s1/2 state and verify the long-term stability of the laser system. Additionally, by performing spectroscopy in a magneto-optical trap we observe strong loss features corresponding to the excitation of s, p, d and higher-l states accessible due to a small electric field.

Electromagnetically induced transparency resonances inverted in magnetic field

The electromagnetically induced transparency (EIT) phenomenon has been investigated in a $\Lambda$-system of the $^{87}$Rb D$_1$ line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates $\gamma_{rel}$ are used: a Rb cell with antirelaxation coating ($L\sim$1 cm) and a Rb nanometric-thin cell (nano-cell) with thickness of the atomic vapor column $L$=795nm. For the EIT in the nano-cell, we have the usual EIT resonances characterized by a reduction in the absorption (i.e. dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (i.e. bright resonances). We suppose that such unusual behavior of the EIT resonances (i.e. the reversal of the sign from DR to BR) is caused by the influence of alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field.

Cooling of macroscopic mechanical resonators in hybrid atom-optomechanical systems

Cooling macroscopic objects is of importance for both fundamental and applied physics. Here we study the optomechanical cooling in a hybrid system which consists of a cloud of atoms coupled to a cavity optomechanical system. On one hand, the asymmetric Fano or electromagnetically induced transparency resonance is explored and the steady-state cooling limits of resonators with frequency ${\ensuremath{\omega}}_{\mathrm{m}}$ are analytically obtained, permitting ground-state cooling of massive low-frequency resonators beyond the resolved sideband limit. On the other hand, due to the excitation-saturation effect, the validity of cooling requires the number of atoms to be much larger than the number of steady-state excitations, which is proportional to ${\ensuremath{\omega}}_{\mathrm{m}}^{\ensuremath{-}2}$. Thus, this limitation plays a minor role in cooling higher-frequency resonators, but becomes important for macroscopic lower-frequency resonators. Under such limitation on the number of atoms, the optimal parameters are quantified. Our study can be a guideline for both theoretical and experimental study of cooling macroscopic objects in atom-optomechanical hybrid systems.

Theoretical and experimental evidence of Fano-like resonances in simple monomode photonic circuits

A simple photonic device consisting of two dangling side resonators grafted at two sites on a waveguide is designed in order to obtain sharp resonant states inside the transmission gaps without introducing any defects in the structure. This results from an internal resonance of the structure when such a resonance is situated in the vicinity of a zero of transmission or placed between two zeros of transmission, the so-called Fano resonances. A general analytical expression for the transmission coefficient is given for various systems of this kind. The amplitude of the transmission is obtained following the Fano form. The full width at half maximum of the resonances as well as the asymmetric Fano parameter are discussed explicitly as function of the geometrical parameters of the system. In addition to the usual asymmetric Fano resonance, we show that this system may exhibit an electromagnetic induced transparency resonance as well as well as a particular case where such resonances collapse in the transmission coefficient. Also, we give a comparison between the phase of the determinant of the scattering matrix, the so-called Friedel phase, and the phase of the transmission amplitude. The analytical results are obtained by means of the Green's function method, whereas the experiments are carried out using coaxial cables in the radio-frequency regime. These results should have important consequences for designing integrated devices such as narrow-frequency optical or microwave filters and high-speed switches. This system is proposed as a simpler alternative to coupled-micoresonators.