Showing papers on "Resonance published in 2022"

Steady-state response of an axially moving circular cylindrical panel with internal resonance

Abstract: With the 3:1 internal resonance , the primary and secondary resonances of an axially moving thin circular cylindrical panel are investigated in the present work. The governing equation and the compatibility equation are established based on the Donnell's nonlinear shell theory and solved to obtain the nonlinear steady-state responses by combining the Galerkin method and the method of multiple scales. The analytical solutions are verified by numerical solutions based on the Runge-Kutta Method. The governing equation includes both the quadratic nonlinearity and the cubic nonlinearity, so the perturbation solutions need to consider three time scales. The quadratic nonlinearity causes the softening behavior of the system. Natural frequencies and the 3:1 internal resonance condition are obtained by the linear analysis. Under the primary resonance , the internal resonance causes the coupling of the first two modes to complicate the nonlinear dynamic response. The response for the second mode possesses an extra bulge or peak due to the internal resonance. The quadratic nonlinearity results in the zero frequency drift and the second-order harmonic. Under the secondary resonance, the exciting force only arouses the second mode. Results are shown to examine the effects of the internal resonance, the exciting force and viscous damping coefficients on the nonlinear dynamic response of an axially moving thin circular cylindrical panel.

Multiphonon-resonance quantum Rabi model and adiabatic passage in a cavity-optomechanical system

Abstract: In this paper, we propose a scheme to achieve a multiphonon-resonance quantum Rabi model and adiabatic passage in a strong-coupling cavity optomechanical system. In the scheme, when the driving bichromatic laser beam is adjusted to the off-resonant j-order red- and blue-sideband, the interaction between the cavity and mechanical oscillator leads to a j-phonon resonance quantum Rabi model. Moreover, we show that there exists a resonant multi-phonon coupling via intermediate states connected by counter-rotating processes when the frequency of the simulated bosonic mode is near a fraction of the transition frequency of the simulated two-level system. As a typical example, we theoretically analyze the two-phonon resonance quantum Rabi model, and derive an effective Hamiltonian of the six-phonon coupling. Finally, we present a method of six-phonon generation based on adiabatic passage across the resonance. Numerical simulations confirm the validity of the proposed scheme. Theoretically, the proposed scheme can be extended to the realization of 3j-phonon state.

Ferromagnetic resonance modes of a synthetic antiferromagnet at low magnetic fields.

Abstract: One key advantage of antiferromagnets over ferromagnets is the high magnetic resonance frequencies that enable ultrafast magnetization switching and oscillations. Among a variety of antiferromagnets, the synthetic antiferromagnet (SAF) is a promising candidate for high-speed spintronic devices design. In this paper, micromagnetic simulations are employed to study the resonance modes in an SAF structure consisting of two identical CoFeB ferromagnetic (FM) layers that are antiferromagnetically coupled via interlayer exchange coupling. When the external bias magnetic field is small enough to ensure the magnetizations of two FM sublayers remain antiparallel alignments, we find that there exist two resonance modes with different precession chirality, namelyy-component synchronized mode andz-component synchronized mode, respectively. These two resonance modes show different features from the conventional in-phase acoustic mode and out-of-phase optic mode. The simulation results are in good agreement with our theoretical analyses.

Experimentally Investigating the Resonance of the Vibration of Two Masses One Spring System Under Different Friction Conditions

Abstract: This report presents some experimental results of the effect of the Coulomb friction on the resonant frequency of the two-mass system connected by a nonlinear leaf spring. The experimental apparatus designed and built has an ability to vary the excitation frequency, the excitation force and friction force. Experimental data show that the resonance frequency of the system tends to decrease when increasing the friction force. The resonant frequency of the system can be expressed as the functions depending both on the amplitude of excitation force and on the Coulomb friction force. The experimental results serve as the basic premise for the development of studies applied in self-movement structure operating under different resistant environments.

Analysis and Design of Surface Plasmon Resonance Waveguide for Sensing Application

Abstract: A surface plasmon resonance waveguide sensor operating in the visible wavelength range is presented for refractive index-based sensing. The silver material is used because of its chemical stability and its strong electromagnetic fields on surface of the nanoparticle. The simulation and modeling of surface plasmon resonance sensor are discussed. The aluminum oxide surface coating material improves the resonance of the sensor because of its stable material properties in optical and chemical application. The three modes of the sensor discussed here are transfer electric, transfer magnetic and the surface plasmon waveguide mode. The effective index value of 1.5178 is observed for the surface plasmon mode of the SPR waveguide sensor. The attenuation loss of 21 dB/cm is obtained at visible wavelength. The sensitivity when averaged for two analyte refractive index is 354 nm/refractive index unit (RIU). The proposed surface plasmons resonance sensor is used as refractive index-based sensor for environmental and chemical monitoring. This proposed work can be used to sense analyte refractive index based on the variation of the change in the resonant wavelength.

Terahertz monolayer metamaterials modulated by high power THz lasers

Abstract: The Terahertz laser modulating processes of monolayers of spheres have been theoretically investigated by using density functional and electromagnetic scattering method. The introduced free energy including static energy, electronic excitations and atomic vibrations was calculated by the density functional method. Thus, the heat capacity, the coefficient of thermal expansion and dielectric constant of materials could be obtained at various temperatures. When the high power THz laser passes through a CdTe sphere, the temperature traces can be changed and calculated by setting any laser waveforms. At a special frequency point, the real parts of permittivity could exhibit an oscillation with double modulation frequency. Furthermore, it was found that the resonance of monolayers could be dynamically tuned, and the oscillation behaviors of transmission are consistent with the modulation waveform. Finally, the resonant frequencies at Terahertz regions could be shifted to a given frequency by adjusting the lattice constants of monolayers.

The multi-RF photon transition driven by strong RF field in optical magnetic resonance of atoms

Abstract: The multiple radio frequency (RF) photon transitions of optical magnetic resonance of 133 Cs atoms are demonstrated theoretically and experimentally. In the presence of a static magnetic field with a fixed direction, the atomic resonance absorption signals irradiated by a circularly polarized light are observed under the condition of different intensities and directions of RF field in our experiment. We find that both the RF intensity and direction can modify the character of the observed signals. If the RF intensity is strong enough, when the RF field is perpendicular to the static magnetic field, only odd number RF photon resonance transitions can be observed. When the RF field is parallel to the static field, no resonance occurs in the experiment. However, if it is between the two cases, all positive integer resonance transitions will be recorded completely. Furthermore, both the analytical solution based on Floquet perturbation theory and the numerical simulation based on Liouville equation strongly support the experimental results. These phenomena enable us to reveal the optical magnetic resonance dynamics more deeply.

The performance of surface enhanced Raman scattering and spatial resolution with triangular plate dimer from ultra-ultraviolet to near-infrared range.

Abstract: The theoretical research on surface enhanced Raman spectroscopy (SERS) of triangular plate dimer (TPD) is of great significance for the design of experimental substrates. In this paper, the SERS properties of the TPD with Au, Ag, Al and Cu have been theoretical investigated in the ultra-ultraviolet, visible and near-infrared region. The influence of the TPD configuration, including the tip radian, the dimer distance and the aspect ratio on the electric field, Raman enhancement and spatial resolution are studied by the finite element method. The results show that there are dipole resonance band and quadruple dipole resonance band in the surface plasmon resonance band of TPD. The tip radian and dimer distance play the dominant role in the electric field enhancement, and the aspect ratio can be mainly used to tune the peak position of the electric field. The smaller tip radian and dimer distance will produce a stronger localized electric field and a small red shift of the peak position. Adjusting the aspect ratio can tune the position of electric field peak from ultraviolet (UV) to near-infrared without changing the peak value of the electric field significantly, especially for Al TPD. The maximum Raman enhancement factor of Au, Ag and Cu all reach 11 orders of magnitude, and 9 orders of magnitude for Al. The spatial resolution changes linearly with the gap distance, and the maximum spatial distributions of Au, Ag, Al and Cu achieve 0.65 nm, 0.67 nm, 0.69 nm and 0.70 nm with the dimer distance of 1 nm. Our results not only provide a better theoretical guidance for the optimization of TPD substrates in the SERS experiment, but also extend its application scope from ultra-UV to near-infrared range.