Showing papers on "Resonance published in 2019"

Aeroacoustic resonance and self-excitation in screeching and impinging supersonic jets – A review:

Abstract: Supersonic jets, particularly shock-containing jets, often exhibit high-intensity, discrete-frequency acoustic tones. These tones are the signature of an aeroacoustic resonance loop established by ...

Gigahertz Frequency Antiferromagnetic Resonance and Strong Magnon-Magnon Coupling in the Layered Crystal CrCl 3

Abstract: We report broadband microwave absorption spectroscopy of the layered antiferromagnet ${\mathrm{CrCl}}_{3}$. We observe a rich structure of resonances arising from quasi-two-dimensional antiferromagnetic dynamics. Because of the weak interlayer magnetic coupling in this material, we are able to observe both optical and acoustic branches of antiferromagnetic resonance in the GHz frequency range and a symmetry-protected crossing between them. By breaking rotational symmetry, we further show that strong magnon-magnon coupling with large tunable gaps can be induced between the two resonant modes.

5 GHz laterally-excited bulk-wave resonators (XBARs) based on thin platelets of lithium niobate

Abstract: In a free-standing 400-nm-thick platelet of crystalline ZY-LiNbO 3 , narrow electrodes (500 nm) placed periodically with a pitch of a few microns can eXcite standing shear-wave bulk acoustic resonances (XBARs), by utilising lateral electric fields oriented parallel to the crystalline Y -axis and parallel to the plane of the platelet. The resonance frequency of ~4800 MHz is determined mainly by the platelet thickness and only weakly depends on the electrode width and the pitch. Simulations show quality-factors ( Q ) at resonance and anti-resonance higher than 1000. Measurements of the first fabricated devices show a resonance Q -factor ~300, strong piezoelectric coupling ~25%, (indicated by the large Resonance-antiResonance frequency spacing, ~11%) and an impedance at resonance of a few ohms. The static capacitance of the devices, corresponds to the imaginary part of the impedance ~100 Ω. This device opens the possibility for the development of low-loss, wide band, RF filters in the 3-6 GHz range for 4th and 5th generation (4G/5G) mobile phones. XBARs can be produced using standard optical photolithography and MEMS processes. The 3rd, 5th, 7th, and 9th harmonics were observed, up to 38 GHz, and are also promising for high frequency filter design.

Nanoribbon-ring cross perfect metamaterial graphene multi-band absorber in THz range and the sensing application

Abstract: In this paper, we propose a graphene nanoribbon-ring cross structure. A multi-band absorber is obtained by a simple combination of graphene nanoribbons and and graphene ring. We obtain that the theoretical absorption of three resonance wavelengths are 99.8%, 98.4% and 65.7%, respectively. We carefully analyzed each resonance wavelength, and the compact structure makes that small changes in the position of graphene nanoribbons and graphene ring have a great influence on the number of resonance wavelength. Meanwhile, the small changes in the chemical potential of graphene can tune the position of resonance wavelengths in the spectrum. At last, we discuss the sensing properties of this structure. The FoM (figure of merit) values of the three resonance wavelengths are high, and the FoM of the three peaks can reach 4.1, 3.679 and 12.66. The absorbers have great adjustability and great application potential in sensing.

Wide range refractive index sensor based on a coupled structure of Au nanocubes and Au film

Abstract: We report a plasmonic refractive index sensor with a wide measurement range based on periodic gold nanocubes coupled with a gold film. The theoretical sensing range is 1.0–1.8. The structure consists of two-dimensional gratings composed of periodic nanocubes that both excite local surface plasmon resonance and stimulate propagating surface plasmon resonance. The strong resonance of the multiple surface plasmons is suitable for use in refractive index sensing and effectively reduces the full width at half maximum of the resonance peak. The sensing performance of each resonant mode in the reflected spectrum is discussed in detail. The highest sensitivity and figure of merit of the proposed sensor are 1002 nm per refractive index units (RIU) and 417 RIU−1, respectively. The proposed sensor will be useful for bio-chemical sensing applications such as measuring changes in the refractive index of gases or liquids.

Strong frequency conversion in heterogeneously integrated GaAs resonators

Abstract: In this contribution, we demonstrate the first integrated gallium arsenide (GaAs) ring resonator for second harmonic generation (SHG) on a GaAs-on-insulator platform. Such resonators exhibit high nonlinear optical coefficients, a strong optical confinement, and intrinsic quality factors exceeding 2.6 × 105, which makes them very attractive for nonlinear optical applications. The fabricated resonators exhibit a great potential for frequency conversion: when 61 μW of pump power at 2 μm wavelength is coupled into the cavity, the absolute internal conversion efficiency is 4%. We predict an external SHG efficiency beyond 1 000 000%/W based on the GaAs resonance devices. Such nonlinear resonant devices of GaAs and its aluminum GaAs alloy can be directly integrated with active components in nonlinear photonic integrated circuits (PICs). This work paves a way for ultra-high efficient and compact frequency conversion elements in PICs.

Resonance Coupling in Heterostructures Composed of Silicon Nanosphere and Monolayer WS2: A Magnetic-Dipole-Mediated Energy Transfer Process.

Abstract: Light-matter resonance coupling is a long-studied topic for both fundamental research and photonic and optoelectronic applications. Here we investigated the resonance coupling between the magnetic dipole mode of a dielectric nanosphere and 2D excitons in a monolayer semiconductor. By coating an individual silicon nanosphere with a monolayer of WS2, we theoretically demonstrated that, because of the strong energy transfer between the magnetic dipole mode of the nanosphere and the A-exciton in WS2, resonance coupling evidenced by anticrossing behavior in the scattering energy diagram was observed, with a mode splitting of 43 meV. In contrast to plexcitons, which involve plasmonic nanocavities, the resonance coupling in this all-dielectric heterostructure was insensitive to the spacing between the silicon nanosphere core and the WS2 shell. Additionally, the two split modes exhibited distinct light-scattering directionality. We further experimentally demonstrated the resonance coupling effect by depositing silicon nanospheres with different diameters onto a WS2 monolayer and collecting the scattering spectra of the resulting heterostructures under ambient conditions. We further demonstrated active control of the resonance coupling by temperature scanning. Our findings highlighted the potential of our all-dielectric heterostructure as a solid platform for studying strong light-matter interactions at the nanoscale.

Chirped Large Mode Area Photonic Crystal Modal Fibers and its Resonance Modes Based on Finite Element Technique

Abstract: The study has outlined the finite element technique used for the fiber modal analysis of photonic crystal fiber (PCF) structure with a hexagonal/circular air holes arrangement on the cladding of pure fiber-optic silica. The used fibers that are namely highly nonlinear fiber (HNLF), single model silica fiber (SMSF) are combined with PCFs with different dopants concentration. Leakage loss, number of guided resonant modes, fiber birefringence, effective refractive index and cross-section areas and nonlinear coefficient parameters are measured inaccurate estimation. The optimum resonant guided modes are also estimated for different lattice infrastructure in circular PCFs.

Tunable hybrid silicon nitride and thin-film lithium niobate electro-optic microresonator.

Abstract: This Letter presents, to the best of our knowledge, the first hybrid Si3N4-LiNbO3-based tunable microring resonator where the waveguide is formed by loading a Si3N4 strip on an electro-optic (EO) material of X-cut thin-film LiNbO3. The developed hybrid Si3N4-LiNbO3 microring exhibits a high intrinsic quality factor of 1.85×105, with a ring propagation loss of 0.32 dB/cm, resulting in a spectral linewidth of 13 pm, and a resonance extinction ratio of ∼27 dB within the optical C-band for the transverse electric mode. Using the EO effect of LiNbO3, a 1.78 pm/V resonance tunability near 1550 nm wavelength is demonstrated.

Fano Resonance in an Asymmetric MIM Waveguide Structure and Its Application in a Refractive Index Nanosensor.

Abstract: Herein, the design for a tunable plasmonic refractive index nanosensor is presented. The sensor is composed of a metal–insulator–metal waveguide with a baffle and a circular split-ring resonator cavity. Analysis of transmission characteristics of the sensor structures was performed using the finite element method, and the influence of the structure parameters on the sensing characteristics of the sensor is studied in detail. The calculation results show that the structure can realize dual Fano resonance, and the structural parameters of the sensor have different effects on Fano resonance. The peak position and the line shape of the resonance can be adjusted by altering the sensitive parameters. The maximum value of structural sensitivity was found to be 1114.3 nm/RIU, with a figure of merit of 55.71. The results indicate that the proposed structure can be applied to optical integrated circuits, particularly in high sensitivity nanosensors.

Space‐Confined Seeded Growth of Cu Nanorods with Strong Surface Plasmon Resonance for Photothermal Actuation

Abstract: Herein, we show that copper nanostructures, if made anisotropic, can exhibit strong surface plasmon resonance comparable to that of gold and silver counterparts in the near-infrared spectrum. Further, we demonstrate that a robust confined seeded growth strategy allows the production of high-quality samples with excellent control over their size, morphology, and plasmon resonance frequency. As an example, copper nanorods (CuNRs) are successfully grown in a limited space of preformed rod-shaped polymer nanocapsules, thereby avoiding the complex nucleation kinetics involved in the conventional synthesis. The method is unique in that it enables the flexible control and fine-tuning of the aspect ratio and the plasmonic resonance. We also show the high efficiency and stability of the as-synthesized CuNRs in photothermal conversion and demonstrate their incorporation into nanocomposite polymer films that can be used as active components for constructing light-responsive actuators and microrobots.

Colored Radiative Cooler under Optical Tamm Resonance

Abstract: We propose a colored radiative cooler assisted by optical Tamm resonance, which features the high-performance cooling effect and high-purity subtractive primary colors (CMY) simultaneously. By deve...

Empowered Layer Effects and Prominent Properties in Few-Layer Metasurfaces

Abstract: DOI: 10.1002/adom.201801477 applications have been realized based on the metamaterials, such as negative index materials,[3] invisibility cloaks,[4] and zeroindex materials.[5] Nevertheless, metamaterials are usually bulky, difficult to be fabricated, and suffer from high energy losses, which hinder their practical applications in modern photonic systems. In recent years, planar metasurfaces, the 2D equivalents of metamaterials, have attracted plenty of attentions due to their extraordinary abilities in controlling the polarization, amplitude, phase, and dispersion of electromagnetic waves.[6–8] Compared with bulk metamaterials, the metasurfaces have many advantages, such as ultrathin thicknesses, low losses, ease of fabrication and integration. Over the past years, single-layer metasurfaces have been widely applied in realizing polarization conversion,[9] beam deflectors,[10,11] metalenses,[12,13] holograms,[14] coding,[15] structural colors,[16,17] nonlinear metasurfaces,[18] and some other applications. Nevertheless, the interactions between lights and ultrathin single-layer metasurfaces are usually limited, resulting in low efficiency and limited controllability in some applications.[19] Moreover, the degrees of freedom for light manipulation provided by a single-layer metasurface are usually not enough in realizing multifunctional devices and some other sophisticated photonic systems. Few-layer metasurface that contains more than one functional layer provides an effective method to overcome the drawbacks of both bulk metamaterials and single-layer metasurfaces. Cheng et al. employed the concept of few-layer metasurfaces to discuss the advantages and emergent functionalities of them in ref. [20]. Few-layer metasurfaces retain the advantages of single-layer metasurfaces and can provide more degrees of freedom to manipulate electromagnetic waves. More importantly, the abundant layer effects, such as the multiple wave interference between layers and the near-field coupling effects, can enhance the interactions between lights and structures and improve the efficiency of few-layer systems. In addition, the combination of different functional layers can produce novel functions that single-layer metasurfaces can hardly realize. For example, by breaking the mirror symmetry along the propagation direction, few-layer metasurfaces can realize asymmetric transmission of linearly polarized lights.[21] By vertically integrating different metasurfaces on one substrate, optical systems with different functions can be miniaturization and integration. Recently, the few-layer metasurfaces have also been extended in the acoustic fields to realize some novel applications, such Metamaterials are 3D artificial structures proposed to surpass conventional natural materials and realize novel functions beyond traditional optical elements. Nevertheless, they are usually bulky and difficult to be fabricated. As 2D equivalents of metamaterials, metasurfaces have been proposed to overcome the drawbacks of metamaterials and fully control the polarization, amplitude, phase, and dispersion of electromagnetic waves. Relative to singlelayer metasurfaces that have limited controllability and functionality, few-layer metasurfaces have more degrees of freedom and abundant layer effects to design novel devices and achieve high-efficiency applications. This review is focused on the empowered layer effects and prominent properties in few-layer metasurfaces, and some distinctive applications proposed in recent years are discussed. It is expected that few-layer metasurfaces will provide a promising road toward the novel intelligent photonic devices, multifunctional devices, and integrated photonic devices.

Evidence of a resonant structure in the $e^+e^-\to \pi^+D^0D^{*-}$ cross section between 4.05 and 4.60 GeV

Abstract: The cross section of the process e^{+}e^{-}→π^{+}D^{0}D^{*-} for center-of-mass energies from 4.05 to 4.60 GeV is measured precisely using data samples collected with the BESIII detector operating at the BEPCII storage ring. Two enhancements are clearly visible in the cross section around 4.23 and 4.40 GeV. Using several models to describe the dressed cross section yields stable parameters for the first enhancement, which has a mass of 4228.6±4.1±6.3 MeV/c^{2} and a width of 77.0±6.8±6.3 MeV, where the first uncertainties are statistical and the second ones are systematic. Our resonant mass is consistent with previous observations of the Y(4220) state and the theoretical prediction of a DD[over ¯]_{1}(2420) molecule. This result is the first observation of Y(4220) associated with an open-charm final state. Fits with three resonance functions with additional Y(4260), Y(4320), Y(4360), ψ(4415), or a new resonance do not show significant contributions from either of these resonances. The second enhancement is not from a single known resonance. It could contain contributions from ψ(4415) and other resonances, and a detailed amplitude analysis is required to better understand this enhancement.

Harmonic Resonance Investigation of a Multi-Inverter Grid-Connected System Using Resonance Modal Analysis

Abstract: This paper addresses the resonance problem in a parallel-inverter-based grid-connected system. Harmonic interactions between inverters and the grid exhibit various number of complicated characteristics that threatens the system stability and power quality. In this paper, a method of harmonic resonance analysis is proposed to investigate the resonance problem in a multi-inverter grid-connected system based on resonance modal analysis (RMA) and participation factor (PF) calculations. Initially, an impedance-based analytical approach is employed and expanded to an electricity distribution network that is dominated by multiple inverters with LCL filters and proportional resonant controllers. Then, the RMA is introduced to investigate the resonant interactions among inverters and the grid. Specifically, harmonic resonance characteristics are addressed through transfer functions and the proposed method considering variation of inverter number, different inverter combinations, and critical system components. Finally, time domain simulations on the PSCAD/EMTDC platform are presented. The case study results validate the effectiveness of the proposed method.

Bragg scattering based acoustic topological transition controlled by local resonance

Abstract: Topological metamaterials offer new routes for control of waves, which are widely realized by Bragg scattering and/or local resonance. Understanding of topological transition by the interaction between these mechanisms is strongly desired to extend the design degrees of freedom for intriguing wave phenomena. Here, we demonstrate a phononic metamaterial consisting of C-shaped elements that enables us to investigate interaction between Bragg scattering and local resonance. We show that by adding resonance scattering a topological band gap is opened from a Bragg scattering based Dirac cone, and its band gap is controlled by the resonance frequency of the cavities relative to the Dirac cone frequency. In addition, we show that topological band-gap opening induced by the Bragg scattering can be reversed into an ordinary state or vice versa by judicious inclusion of the local resonance. Scattering cross-section analysis elaborates the combined effect of the two mechanisms on topological states. By employing lossy resonant elements, we further demonstrate a lossy topological insulator capable of one-way sound propagation immune to sharp corners, potentially leading to an energy-harvesting topological insulator. Our results provide a critical understanding of topological phenomena involving coupled scattering mechanisms.

Langevin Approach to Quantum Optics with Molecules

Abstract: We investigate the interaction between light and molecular systems modeled as quantum emitters coupled to a multitude of vibrational modes via a Holstein-type interaction. We follow a quantum Langevin equations approach that allows for analytical derivations of absorption and fluorescence profiles of molecules driven by classical fields or coupled to quantized optical modes. We retrieve analytical expressions for the modification of the radiative emission branching ratio in the Purcell regime and for the asymmetric cavity transmission associated with dissipative cross talk between upper and lower polaritons in the strong coupling regime. We also characterize the F\"orster resonance energy transfer process between donor-acceptor molecules mediated by the vacuum or by a cavity mode.

Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources.

Abstract: We analyse the resonant mode structure and local density of states in high-Q hybrid plasmonic-photonic resonators composed of dielectric microdisks hybridized with pairs of plasmon antennas that are systematically swept in position through the cavity mode. On the one hand, this system is a classical realization of the cooperative resonant dipole–dipole interaction through a cavity mode, as is evident through predicted and measured resonance linewidths and shifts. At the same time, our work introduces the notion of ‘phased array’ antenna physics into plasmonic-photonic resonators. We predict that one may construct large local density of states (LDOS) enhancements exceeding those given by a single antenna, which are ‘chiral’ in the sense of correlating with the unidirectional injection of fluorescence into the cavity. We report an experiment probing the resonances of silicon nitride microdisks decorated with aluminium antenna dimers. Measurements directly confirm the predicted cooperative effects of the coupled dipole antennas as a function of the antenna spacing on the hybrid mode quality factors and resonance conditions.

Theoretical Investigation of a Highly Sensitive Refractive-Index Sensor Based on TM₀ Waveguide Mode Resonance Excited in an Asymmetric Metal-Cladding Dielectric Waveguide Structure.

Abstract: This study proposes a highly sensitive refractive-index (RI) sensor based on a TM₀ waveguide mode resonance excited in an asymmetric metal-cladding dielectric waveguide structure, where the analyte serves as the guiding layer. By scanning the wavelength at fixed angles of incidence, the reflection spectra of the sensor were obtained. The results showed that the resonance wavelength redshifted dramatically with increases in the analyte RI, which indicates that this approach can be used to sense both the resonance wavelength and the analyte RI. Based on this approach, we investigated the sensing properties, including the sensitivity and figure of merit, at fixed incident angles of 60° and 45°, at which the sensitivity of the sensor reached 7724.9 nm/RIU (refractive index units) and 1339 nm/RIU, respectively. Compared with surface plasmon resonance sensors, which are based on a similar structure, the proposed sensor can accept a more flexible range of incident angles and a wider sensing range of analyte RI. This approach thus has tremendous potential for use in numerous sensing domains, such as biochemical and medical analyses.

Soliton and quasi-soliton frequency combs due to second harmonic generation in microresonators

Abstract: We report how a doublet of the symmetric oppositely tilted bistable resonance peaks in a microring resonator with quadratic nonlinearity set for generation of the second harmonic can transform into a Kerr-like peak on one side of the linear cavity resonance and into a closed loop structure disconnected from the quasi-linear resonance on the other. Both types of the nonlinear resonances are associated with the formation of the soliton combs for dispersion profiles of a typical LiNbO 3 microring. We report bright quasi-solitons propagating on a weakly modulated low intensity background when the group velocity dispersions have the opposite signs for the fundamental and second harmonic. We also show exponentially localized solitons when the dispersion signsare the same. Finally, we demonstrate that the transition between these two types of soliton states is associated with the closure of the forbidden gap in the spectrum of quasi-linear waves.

Photonic Microcavity-Enhanced Magnetic Plasmon Resonance of Metamaterials for Sensing Applications

Abstract: We first investigate numerically photonic microcavity-enhanced magnetic plasmon (MP) resonance in metamaterials for high-quality refractive index sensing. The metamaterials consist of a top periodic array of U-shaped metallic split-ring resonators (SRRs), a middle dielectric layer, and a bottom metallic backed plate. The top metallic SRRs that are placed at about Bragg distance above the bottom metallic plate constitute a photonic microcavity. Because the MP resonance excited in metallic SRRs is coupled to the photonic microcavity mode supported by the photonic microcavity, the radiative damping of the MP resonance is strongly reduced, and consequently, its linewidth is decreased dramatically. Benefiting from the narrow linewidth, large modulation depth, and giant magnetic field enhancement at the MP resonance, the cavity-coupled metamaterial sensor has very high sensitivity ( $\text {S}= 400$ nm/RIU and $\text {S}^{\ast } = 26$ /RIU) and figure of merit ( $\text {FOM}= 33$ and FOM* = 4215), which suggests that the proposed metamaterials have potential in applications of plasmonic biosensors.

Strong and tunable plasmonic field coupling and enhancement generating from the protruded metal nanorods and dielectric cores

Abstract: Numerical investigation of resonant peak by modifying the number of protruded metal nanorods (MNRDs) and the core material in metal nanoshells for near field intensity are explored by means of the finite element method. The surface plasmon effect arising from the core cases with/without the protruded MNRDs was compared along with that arose from their solid counterparts. A strong and tunable field coupling and enhancement effects corresponding to the transverse surface plasmon resonance (SPR) and cavity plasmon resonance (CPR) modes are observed. It is found that the near field intensity spectra obtained from the silver and silver-shell nanorods with the protruded silver nanorods is approximately 2.5–3.0 times larger than that of the silver nanorods without the protruded silver nanorods. The peak resonance wavelength shows a red shift as the increasing of the permittivity in the core regions and the number of the protruded MNRDs. This indicates that the core regions and the protruded MNRDs can significantly mediate the EM waves coupling and enhancing the plasmonic effects and play a key role to tune the peak resonance wavelengths position. The investigated nanostructures offer multiple design freedoms to modulate the peak resonant wavelength and electromagnetic wave properties.

A fully coupled subwavelength resonance approach to filtering auditory signals

Abstract: The aim of this paper is to understand the behaviour of a large number of coupled subwavelength resonators. We use layer potential techniques in combination with numerical computations to study an ...