Resonator Configuration Research Articles

Puzzling out the coexistence of terrestrial planets and giant exoplanets

Aims. Hundreds of giant planets have been discovered so far and the quest of exo-Earths in giant planet systems has become intriguing. In this work, we aim to address the question of the possible long-term coexistence of a terrestrial companion on an orbit interior to a giant planet, and explore the extent of the stability regions for both non-resonant and resonant configurations. Methods. Our study focuses on the restricted three-body problem, where an inner terrestrial planet (massless body) moves under the gravitational attraction of a star and an outer massive planet on a circular or elliptic orbit. Using the detrended fast Lyapunov indicator as a chaotic indicator, we constructed maps of dynamical stability by varying both the eccentricity of the outer giant planet and the semi-major axis of the inner terrestrial planet, and identify the boundaries of the stability domains. Guided by the computation of families of periodic orbits, the phase space is unravelled by meticulously chosen stable periodic orbits, which buttress the stability domains. Results. We provide all possible stability domains for coplanar symmetric configurations and show that a terrestrial planet, either in mean-motion resonance or not, can coexist with a giant planet, when the latter moves on either a circular or an (even highly) eccentric orbit. New families of symmetric and asymmetric periodic orbits are presented for the 2/1 resonance. It is shown that an inner terrestrial planet can survive long time spans with a giant eccentric outer planet on resonant symmetric orbits, even when both orbits are highly eccentric. For 22 detected single-planet systems consisting of a giant planet with high eccentricity, we discuss the possible existence of a terrestrial planet. This study is particularly suitable for the research of companions among the detected systems with giant planets, and could assist with refining observational data.

Label-free sensing of ultralow-weight molecules with all-dielectric metasurfaces supporting bound states in the continuum

The realization of an efficient optical sensor based on a photonic crystal metasurface supporting bound states in the continuum is reported. Liquids with different refractive indices, ranging from 1.4000 to 1.4480, are infiltrated in a microfluidic chamber bonded to the sensing dielectric metasurface. A bulk liquid sensitivity of 178 nm/RIU is achieved, while a Q-factor of about 2000 gives a sensor figure of merit up to 445 in air at both visible and infrared excitations. Furthermore, the detection of ultralow-molecular-weight (186 Da) molecules is demonstrated with a record resonance shift of 6 nm per less than a 1 nm thick single molecular layer. The system exploits a normal-to-the-surface optical launching scheme, with excellent interrogation stability and demonstrates alignment-free performances, overcoming the limits of standard photonic crystals and plasmonic resonant configurations.

HTS YBCO Resonator Configuration With a Coplanar Optimized Flux Concentrator Strongly Coupled to rf SQUID

We developed a novel magnetic coupling module formed of a monolayer superconducting flux concentrator, which is integrated with a coplanar resonator strongly coupled to HTS rf-SQUID. Three types of resonators, including a long stripline resonator between input loop and pick-up loop of the flux concentrator, a complementary split ring resonator (CSRR), and also a spiral shape inside the input loop are explored. The resonance quality factors as well as the coupling to the SQUID of different patterns of these three types of the resonators is evaluated using Finite Element Method (FEM) simulations. Several readout methods to couple the electronic system to the resonators are tested, including inductive (coil) and capacitive (transmission line) couplings, and the optimum readout is reported for each of the resonators. Among the evaluated resonator types, a spiral shape resonator with optimal design showing the highest quality factor (5900) together with the strongest coupling to the SQUID (-0.5 dB) at resonance frequency of 836 MHz, is fabricated using 200 nm thick superconducting YBCO on a 1 mm thick crystalline LaAlO3 substrate. The flux concentrator of the module is optimized by the variation of its linewidths and also its input loop radius to obtain maximum flux transformation efficiency.

Do Optomechanical Metasurfaces Run Out of Time?

Artificially structured metasurfaces make use of specific configurations of subwavelength resonators to efficiently manipulate electromagnetic waves. Additionally, optomechanical metasurfaces have the desired property that their actual configuration may be tuned by adjusting the power of a pump beam, as resonators move to balance pump-induced electromagnetic forces with forces due to elastic filaments or substrates. Although the reconfiguration time of optomechanical metasurfaces crucially determines their performance, the transient dynamics of unit cells from one equilibrium state to another is not understood. Here, we make use of tools from nonlinear dynamics to analyze the transient dynamics of generic optomechanical metasurfaces based on a damped-resonator model with one configuration parameter. We show that the reconfiguration time of optomechanical metasurfaces is not only limited by the elastic properties of the unit cell but also by the nonlinear dependence of equilibrium states on the pump power. For example, when switching is enabled by hysteresis phenomena, the reconfiguration time is seen to increase by over an order of magnitude. To illustrate these results, we analyze the nonlinear dynamics of a bilayer cross-wire metasurface whose optical activity is tuned by an electromagnetic torque. Moreover, we provide a lower bound for the configuration time of generic optomechanical metasurfaces. This lower bound shows that optomechanical metasurfaces cannot be faster than state-of-the-art switches at reasonable powers, even at optical frequencies.

An I/O Coupling Multiplier Circuit and Its Application to Wideband Filters and Diplexers

In this paper, a novel input/output (I/O) coupling multiplier circuit for conveniently increasing I/O coupling of a wideband coupled-resonator filter/diplexer is proposed. The multiplier circuit consists of a shunt capacitor and a negative phase shift. By appropriately shunt connecting a capacitor in the vicinity of an I/O port, the I/O coupling can be effectively increased. Compared to conventional approaches of increasing I/O coupling for a wideband application, using the multiplier circuit allows much less perturbing the resonant frequency of the first resonator. For many resonator configurations such as helical resonator, to which the tapping probe could not be adjusted continuously, the multiplier circuit provides a convenient way to control I/O coupling. In this paper, the working mechanism of the proposed circuit is well proved theoretically. The usefulness of the multiplier circuit has been demonstrated for coaxial combline cavity resonators and helical resonators, both for filter and diplexer applications. As a practical example, the multiplier circuit is applied to a wideband UHF helical resonator diplexer.

Formation of terrestrial planets in eccentric and inclined giant planet systems

Aims. Evidence of mutually inclined planetary orbits has been reported for giant planets in recent years. Here we aim to study the impact of eccentric and inclined massive giant planets on the terrestrial planet formation process, and investigate whether it can possibly lead to the formation of inclined terrestrial planets. Methods. We performed 126 simulations of the late-stage planetary accretion in eccentric and inclined giant planet systems. The physical and orbital parameters of the giant planet systems result from n-body simulations of three giant planets in the late stage of the gas disc, under the combined action of Type II migration and planet-planet scattering. Fourteen two- and three-planet configurations were selected, with diversified masses, semi-major axes (resonant configurations or not), eccentricities, and inclinations (including coplanar systems) at the dispersal of the gas disc. We then followed the gravitational interactions of these systems with an inner disc of planetesimals and embryos (nine runs per system), studying in detail the final configurations of the formed terrestrial planets. Results. In addition to the well-known secular and resonant interactions between the giant planets and the outer part of the disc, giant planets on inclined orbits also strongly excite the planetesimals and embryos in the inner part of the disc through the combined action of nodal resonance and the Lidov–Kozai mechanism. This has deep consequences on the formation of terrestrial planets. While coplanar giant systems harbour several terrestrial planets, generally as massive as the Earth and mainly on low-eccentric and low-inclined orbits, terrestrial planets formed in systems with mutually inclined giant planets are usually fewer, less massive (<0.5 M⊕), and with higher eccentricities and inclinations. This work shows that terrestrial planets can form on stable inclined orbits through the classical accretion theory, even in coplanar giant planet systems emerging from the disc phase.

Widely Wavelength-Tunable Mid-Infrared Fluoride Fiber Lasers

We demonstrate widely wavelength-tunable conti-nuous-wave (CW) and Q-switched Er3+-doped ZBLAN fluoride fiber lasers operating around 3 μm enabled by a volume Bragg grating (VBG). In the CW operation regime, a total wavelength tuning range of over 160-nm spanning from 2694 to 2854 nm has been achieved. For the Q-switched mode of operation, a slightly modified resonator configuration, incorporating a passive Q-switcher, topological insulator Bi2Te3 nanosheets, can produce stable pulse trains with a pulse width of 880 ns at a repetition rate of 81 kHz, while maintaining a wavelength tuning range of 62 nm from 2762 to 2824 nm through adjusting the VBG. In both operation regimes, the output spectral width is measured to be <0.3 nm (full-width at half-maximum) over the whole tuning range. Our work both demonstrates the great wavelength-tuning potential of the Er3+ -doped fluoride fiber laser, and also paves a way for the development of a range of high-performance midinfrared laser sources.

A novel photonic crystal ring resonator configuration for add/drop filtering

A novel compact photonic crystal ring resonator (PCRR) configuration is proposed to realize high-efficiency waveguided add-drop filtering. Its wavelength selection and dropping-direction exchange functions are demonstrated numerically. The working mechanism of this nested dual-loop resonant cavity structure is analyzed in detail.

Molecular Sensing and Color Manipulation Based on Dimension-Controlled Plasmon-Enhanced Silicon Nanotube SERS Substrates

The system of suspended gold nanoring on silicon nanotube substrate with enhanced light harvesting and electromagnetic field enhancements was proposed in the present study. The effects of outer/inner diameter (D/d) ratio of the ring and tube on the plasmonic behavior were studied by systemic simulations and experiments. In simulations, the high order quadrupole–dipole mode was also excited in addition to the typical dipole–dipole mode, and the resonant configurations were characterized by both electric field profile and resonant surface charge distribution. Experimentally, both dark-field and Raman microscopies were conducted to examine the plasmonic behavior. The plasmon-enhanced scattering could be controlled by tailoring the D/d ratio, and the dark-field image colors could be manipulated covering the visible range. Raman spectra using two excitation wavelengths were also recorded and showed good agreement with calculated enhancement factor which, in turn, provided the evidence of the evolution of reson...

Inclined asymmetric librations in exterior resonances

Librational motion in celestial mechanics is generally associated with the existence of stable resonant configurations and signified by the existence of stable periodic solutions and oscillation of critical (resonant) angles. When such an oscillation takes place around a value different than 0 or $\pi$, the libration is called asymmetric. In the context of the planar circular restricted three-body problem (CRTBP), asymmetric librations have been identified for the exterior mean-motion resonances (MMRs) 1:2, 1:3 etc. as well as for co-orbital motion (1:1). In exterior MMRs the massless body is the outer one. In this paper, we study asymmetric librations in the 3-dimensional space. We employ the computational approach of Markellos (1978) and compute families of asymmetric periodic orbits and their stability. Stable, asymmetric periodic orbits are surrounded in phase space by domains of initial conditions which correspond to stable evolution and librating resonant angles. Our computations were focused on the spatial circular restricted three-body model of the Sun-Neptune-TNO system (TNO= trans-Neptunian object). We compare our results with numerical integrations of observed TNOs, which reveal that some of them perform 1:2-resonant, inclined asymmetric librations. For the stable 1:2 TNOs librators, we find that their libration seems to be related with the vertically stable planar asymmetric orbits of our model, rather than the 3-dimensional ones found in the present study.

Neutron tunneling in nanostructured systems: isotopical effect

AbstractThis contribution reports, to the best of our knowledge, for the first time on the neutron tunneling phenomenon in nickel isotopes based nanostructured. More accurately, 58Ni-62Ni-58Ni thin films Fabry-Perot resonator configuration exhibited several tunneling resonances. In total, there were 7 tunneling resonances. These tunneling resonances manifest themselves via sharp dips in the total reflection plateau due to quasi-bound states in the nanostructured isotopic based nickel thin film Fabry-Perot resonator.

Design and implementation of optical switches based on nonlinear plasmonic ring resonators: Circular, square and octagon

In this paper, all-optical plasmonic switches (AOPS) based on various configurations of circular, square and octagon nonlinear plasmonic ring resonators (NPRR) were proposed and numerically investigated. Each of these configurations consisted of two metal-insulator-metal (MIM) waveguides coupled to each other by a ring resonator (RR). Nonlinear Kerr effect was used to show switching performance of the proposed NPRR. The result showed that the octagon switch structure had lower threshold power and higher transmission ratio than square and circular switch structures. The octagon switch structure had a low threshold power equal to 7.77 MW/cm2 and the high transmission ratio of approximately 0.6. Therefore, the octagon switch structure was an appropriate candidate to be applied in optical integration circuits as an AOPS.

Compact and intense parametric x-ray radiation source based on a linear accelerator with cryogenic accelerating and decelerating copper structures

This paper describes a proposal for a compact x-ray source based on parametric x-ray radiation (PXR). The PXR, which is produced when a single crystal is bombarded with relativistic electrons, has good monochromaticity and spatial coherence, and is expected to be well suited for imaging of low-Z materials and medical application. The proposed system employs a pair of copper accelerating structures which are operated at a cryogenic temperature of 20 K and arranged to form a resonant ring configuration. The electron beam is once accelerated up to 75 MeV in one of the structures, being decelerated down to lower than 7 MeV in the other structure after generating PXR at a single crystal, and then dumped. The expected x-ray yield is $1{0}^{9}\text{ }\text{ }\mathrm{photons}/\mathrm{s}$ at a center energy of 15 keV or higher.

Compact 2.45 GHz ECR Ion Source for generation of singly-charged ions

2.45 GHz ECR ion sources are widely used for production of protons, single charged heavy ions and secondary radioactive ion beams. This paper describes the development of a compact ECR ion source based on 2.45 GHz coaxial resonator. The first results of extracted current measurements at different resonator configuration as a function of UHF frequency, power and gas flow are presented.

The rectilinear three-body problem as a basis for studying highly eccentric systems

The rectilinear elliptic restricted Three Body Problem (TBP) is the limiting case of the elliptic restricted TBP when the motion of the primaries is described by a Keplerian ellipse with eccentricity $e'=1$, but the collision of the primaries is assumed to be a non-singular point. The rectilinear model has been proposed as a starting model for studying the dynamics of motion around highly eccentric binary systems. Broucke (1969) explored the rectilinear problem and obtained isolated periodic orbits for mass parameter $\mu=0.5$ (equal masses of the primaries). We found that all orbits obtained by Broucke are linearly unstable. We extend Broucke's computations by using a finer search for symmetric periodic orbits and computing their linear stability. We found a large number of periodic orbits, but only eight of them were found to be linearly stable and are associated with particular mean motion resonances. These stable orbits are used as generating orbits for continuation with respect to $\mu$ and $e'<1$. Also, continuation of periodic solutions with respect to the mass of the small body can be applied by using the general TBP. FLI maps of dynamical stability show that stable periodic orbits are surrounded in phase space with regions of regular orbits indicating that systems of very highly eccentric orbits can be found in stable resonant configurations. As an application we present a stability study for the planetary system HD7449.

Resonant inductive-coupling configurations with load-independent transfer-parameters for wireless power transfer – a perspective from the transformer equivalent-models

ABSTRACTIn inductive power transfer (IPT), the possibility of load regulation (voltage or current regulation) in some resonant configurations has been reported in previous works. However, the underlying formalism is still incomplete or too involved, obscuring the fundamental aspects. In this paper, the author exposes the causes and possibilities of load regulation from the perspective of some equivalent models of the linear transformer, in a unifying and systematic approach that eases the design process. The equivalent models of interest are based on two or three uncoupled inductors and on the ideal transformer or the ideal gyrator. Based on these models, the author presents several possible resonant configurations, some of them absent from the IPT literature. In all these configurations, the alignment concept is extensively used for a clear categorization of the related load-regulation phenomena. However, the main novelty of the paper is on the three-inductor models: the author demonstrates that there are an infinite number of such models, which enable an infinite number of load-regulation possibilities, opening new research paths. At last, the author presents an efficient 250 W contactless connector system with intrinsic voltage regulation as a practical application example of some of the principles exposed in this paper.

Preparation of Highly Conductive Yarns by an Optimized Impregnation Process

We report the development of the electrical conductivity in textile yarns through impregnation and post-treatment of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The conductive polymer is deposited on fibers, which fills the gap space within the hierarchical structure of the yarns. Organic nonpolar solvents act as reducing agent to increase the density of PEDOT moieties on the yarns, galvanizing increment in conductivity values. Post-treatment by ethylene glycol transforms the resonance configuration of the conductive moieties of conjugated polymer, which helps in further enhancement of electrical conductivity of the yarns. We have optimized the method in terms of loading and conformal change of the polymer to have a lesser resistance of the coated conductive yarns. The minimum resistance achieved has a value of 77 Ωcm−1. This technique of developing conductivity in conventional yarns enables retaining the flexibility of yarns and feeling of softness which would find suitable␣applications for wearable electronics.

Analysis of high-resolution electro-optical beam steering by long-range surface plasmon resonance using a ZnSe prism.

A proposal on high-resolution electro-optical beam steering is conceptualized analytically using a long-range surface plasmon resonance configuration comprising a liquid crystal layer of E44 for 1550nm wavelength. With the tuning of the refractive index of E44 through variations of applied voltage from 0 to 10V, an optical beam steering can be attained considering the composite effect of spatial and angular Goos-Hanchen and Imbert-Fedorov shifts. As compared with the existing beam shift processes in μrad by mechanical means, here, the computed angular resolution is 3.40nrad. The proposed idea finds a new avenue in the field of pulse generation, optical sensor applications, and atomic force microscopy, mitigating existing drawbacks.

Effect of muscle soft tissue on biomechanics of lumbar spine under whole body vibration

The object of this study was to simulate effect of muscle soft tissue on resonant frequencies and configuration (deformation and displacement) of lumbar spine in vivo under whole-body vibration (WBV). The three-dimensional (3D) finite element (FE) models of human body including skin, muscle soft tissue, viscera, ligaments, lumbar intervertebral disc (LID) and skeleton were created and validated. Modal analysis was performed by FE method. Results were that muscle soft tissue increased the resonant frequencies of lumbar spine. The first vertical resonant frequency (FVRF) changed greatly with the variation of Young’s modulus of muscle soft tissue in range of 0.01 MPa-0.15 MPa. Muscle soft tissue reduced the modal displacement of the lumbar spine. Especially the modal displacement in the anteroposterior direction was reduced by at least 40%. The risk injury area of lumbar was at low lumbar region under vertical WBV. The conclusions were that muscle soft tissue played a very important role in biomechanics of lumbar spine, and we could contract muscles of whole body for protection of lumbar spine under WBV with high vibration amplitude. The findings could be helpful in understanding the biomechanics of lumbar spine under WBV and offer potential references for spinal disease protection and orthopedics.

Robust highly stable multi-resonator refractive index sensor

Here we show that a serial array of three evanescently coupled microring resonators can achieve detection limits for refractive index changes in the surrounding environment that are more than 40% better than a single resonator. The improved performance of the three rings occurs when only the central resonator is exposed to the refractive index change and is due to the narrower linewidth that results from the off-resonant coupling to the adjacent resonators. Unlike a single resonator sensor that is usually operated close to critical coupling to maximize the sensitivity, the three resonator configuration is able to achieve superior detection limits over a wide range of inter-resonator couplings. We use this to show that random variations of the couplings resulting from manufacturing variations has a minimal impact on the performance of the three ring system.