A Novel Analytical Study of Anisotropic Multi-Layer Elliptical Structures Containing Graphene Layers

A general approach, which can derive dispersion relations efficiently and automatically for infinite layered structures with any number of piezoelectric and elastic layers, is proposed in this paper. Based on Stroh formalism and dual variable and position method, the general relationship between top and bottom variables of single layer is obtained firstly. Considering those different layups possibly appearing in multilayered structures, three base cases are presented in detail. By combing these base cases repeatedly from the bottom of the plates to the top, we can easily write programming codes to derive dispersion relations for any general multilayered structures automatically. The results show great conformity with the reported work and simultaneously prove the ability of our approach for complex and generally anisotropic multilayered structure. Above all, this general approach is efficient and superior to get the dispersion relations, which is convenient for further study of wave propagation characteristics in general multilayered structures.

This paper primarily explores the modeling method of n-level complex helical structures with coal mining machine cables as the research object. The paper first elaborately introduces the modeling method of n-level helix curves based on parametric equations and coordinate transformations, and compensates for the n-level helix curves with corrected pitch, which can obtain more accurate n-level helix curves and improve the accuracy of n-level helix curves modeling. Subsequently, based on this high-precision n-level helix curves modeling method, the paper elaborates on the method of solving pitch and twisting radius of multi-layer helical structure. Calculation scripts were written based on the above methods, which can be used to batch calculate the twisting radius and pitch of each layer structure in multi-layer structures when satisfying the conditions of in-layer tangency, inter-layer tangency, and extrusion deformation, and retain the actual results through logical judgment. Then, based on the above two methods, the paper developed a modeling method for braided structures based on piecewise functions containing fifth-order polynomials, which can effectively avoid the problem of insufficiently dense arrangement of braided lines and easy interference in traditional methods. Finally, a set of modeling tools was developed using C# and Python in Grasshopper to implement the modeling algorithm. Taking the MCPT-1.9/3.3 3120 + 170 + 4 * 10 coal mining machine cable as an example. The cable was modeled using both the method proposed in this paper and the traditional method. Comparative data shows that the method proposed in this paper can reduce errors by 3.31E6 times in the second-level and above helical structures. In addition this paper compares the standard line length, measured line length, and the line length established by the proposed model, showing that the relative errors are both less than 0.1941%. This paper provides a new, systematic, high-precision, and full-process cable modeling method, in which all parameters except the process parameters are accurately solved by equations. It lays a theoretical foundation for the high-precision simulation and intelligent sensing cables, which is of great significance for improving the safety, stability, and efficient development of the coal mining industry. The research results of the paper can not only be applied to the modeling of coal mining machine cables but also can be extended to the modeling of other complex multi-layer helical structures.

We report on a highly sensitive measurement of the relative humidity (RH) of moist air using both the surface plasmon resonance (SPR) and Bloch surface wave resonance (BSWR). Both resonances are resolved in the Kretschmann configuration when the wavelength interrogation method is utilized. The SPR is revealed for a multilayer plasmonic structure of SF10/Cr/Au, while the BSWR is resolved for a multilayer dielectric structure (MDS) comprising four bilayers of TiO/SiO with a rough termination layer of TiO. The SPR effect is manifested by a dip in the reflectance of a p-polarized wave, and a shift of the dip with the change in the RH, or equivalently with the change in the refractive index of moist air is revealed, giving a sensitivity in a range of 0.042–0.072 nm/%RH. The BSWR effect is manifested by a dip in the reflectance of the spectral interference of s- and p-polarized waves, which represents an effective approach in resolving the resonance with maximum depth. For the MDS under study, the BSWRs were resolved within two band gaps, and for moist air we obtained sensitivities of 0.021–0.038 nm/%RH and 0.046–0.065 nm/%RH, respectively. We also revealed that the SPR based RH measurement is with the figure of merit (FOM) up to 4.7 × 10−4 %RH, while BSWR based measurements have FOMs as high as 3.0 × 10 %RH and 1.1 × 10−3 %RH, respectively. The obtained spectral interferometry based results demonstrate that the BSWR based sensor employing the available MDS has a similar sensitivity as the SPR based sensor, but outperforms it in the FOM. BSW based sensors employing dielectrics thus represent an effective alternative with a number of advantages, including better mechanical and chemical stability than metal films used in SPR sensing.

We present a novel kind of optical sensor based on the electromagnetically induced transparency (EIT)-like effect in a Tamm plasmon multilayer structure, which consists of a metal film on a dielectric Bragg grating with alternatively stacked TiO2 and SiO2 layers and a defect layer. The defect layer can induce a refractive-index-sensitive ultranarrow peak in the broad Tamm plasmon reflection dip. This nonintuitive phenomenon in analogy to the EIT effect in atomic systems originates from the coupling and destructive interference between the defect and Tamm plasmon modes in the multilayer structure. Taking advantage of this EIT-like effect, we achieve an ultrahigh sensing performance with a sensitivity of 416nm/RIU and a figure of merit (FOM) of 682 RIU-1. The numerical simulations agree well with the theoretical calculations. Additionally, the spectral line shape can be effectively tailored by changing the defect layer thickness, significantly promoting the dimensionless FOM from 0.76×104 to more than 2.4×104. Our findings will facilitate the achievement of ultrasensitive optical sensors in multilayer structures and open up perspectives for practical applications, especially in gas, biochemical, and optofluidic sensing.

Ion Beam Assisted Deposition Enhanced Thermoelectric Properties (with Figure of Merit Above 3.0)

Graphene monolayer of sub-nanometer thickness shows strong metallic and plasmonic behavior in terahertz (THz) frequency range. This plasmonic effect varies considerably when graphene layer is placed under a magnetic field of appropriate strength. The strong adsorption characteristic of graphene layer is another advantage. In this work, a photonic spin Hall effect (PSHE)-based plasmonic sensor consisting of germanium prism, organic dielectric layer, and graphene monolayer is simulated and analyzed in THz aiming at highly sensitive and reliable sensing under variable magnetic field. Modified Otto configuration and magneto-optic effect in graphene are considered. The sensor’s performance is examined in terms of sensitivity, limit of detection (LOD), and figure of merit (FOM). The analysis indicates that LOD of the order of 10−5 RIU for gas sensing is achievable, which is finer than recently reported gas sensors based on different techniques. Further, the FOM improves when a larger magnitude of magnetic field is applied. The FOM is even greater for rarer gaseous media, which can make the sensor extremely useful in early detection of airborne viruses such as SARS-Cov-2 (while using appropriate specificity method) and to measure the concentration of a particular gas in a given gaseous mixture. The results further indicate that the same sensor design can be used for magnetic field detection while the FOM of magnetic field detection is significantly greater for rarer gaseous medium (e.g., air), which may enable the probe to be used in early detection of radiation leakage in nuclear reactors. For larger magnitudes of magnetic field, the corresponding LOD becomes finer.

During the development of ferrite-loaded accelerating cavities, the electromagnetic properties of the dispersive ferrite material need to be known. We describe a coaxial short-circuit measurement technique to measure the complex permeability of toroidal-shaped samples (127mm outer and 70mm inner diameter) that are exposed to an external magnetic bias field. The external magnetic bias field is applied perpendicular to the RF magnetic field. With this method it is possible to characterize the frequency dependence of the permeability for a frequency range of 1100MHz. The dependence of the permeability on the external magnetic bias is presented for the ferrite G-510 from Trans-Tech Inc. and the material characterization is shown in the same frequency range. The measurement results are verified by simulations of the measurement set-up.

In this paper, a general recipe is proposed to design an efficient graphene-integrated plasmonic structure for third harmonic generation. Specifically, the design procedure for an integrated graphene-based ultraviolet light generator is presented. In order to enhance the field intensity at the graphene layer, two distinct mechanisms are utilized. A multilayer Bragg structure is used as a perfect magnetic conductor to make a constructive interference between incident and reflected field at the graphene layer. A periodic array of shaped resonant gold nanoparticles is placed on top of the graphene sheet to enhance the field intensity due to the plasmonic resonance at the fundamental frequency. A hybrid and fast numerical method based on the scattering matrix of Floquet modes and the Generalized Multipole Technique is also proposed to analyze the periodic structure. This numerical method is used to optimize the dimensions of the multilayer structure and boost the nonlinear conversion efficiency by more than $10^6$ times.

Sandwich magnetoelectric composites of PZT/NFO/PZT (PNP) have been prepared by laminating PZT5, NiFe2O4, and PZT5 ceramics in turn with polyvinyl alcohol (PVA) paste. A systematic study of structural, magnetic and ferroelectric properties is undertaken. Structural studies carried out by X-ray diffraction indicate formation of cubic perovskite phase of PZT5 ceramic and cubic spinel phase of NiFe2O4 ceramic. As increasing the content of PZT5 phase, ferroelectric loops and magnetic loops of PNP composites showed increasing remnant electric polarizations and decreasing remnant magnetic moments separately. Both external magnetic fields and bias voltages could regulate the basal radial resonance frequency of the composites, which should be originated with the transformation and coupling of the stress between the piezoelectric phase and magnetostrictive phase. Such magnetoelectric composite provides great opportunities for electrostatically tunable devices.

Influence of geometric and material parameters on the damping properties of multilayer structures

We examine the efficacy of Dark-mode plasmonics as a platform for enhanced\nmagneto-optics. Dark-mode of a small particle consists of two co-existing\nequal-intensity and mutually opposing dipolar excitations. Each of these two\nopposing dipoles may even resonate at or near the dark-mode frequency, but the\nnet dipole moment vanishes due to the mutual cancelation between the opposing\ndipoles. We show that application of external magnetic bias may alleviate the\nintense destructive interference. Furthermore, under external magnetic bias the\nopposing dark-resonances of a plasmonic particle shift in opposite directions\nand create a region of extremely sensitive Faraday rotation. We show that the\nmagnetized dark resonance in lossless Ag-like particle may provide more than 20\ndegrees rotation under magnetic fields of the order of 1-2 Tesla, exhibiting\nmagneto-plasmonic activity that is 2-3 orders of magnitude larger than that\nobserved in conventional plasmonic particle of the same material.\n

The aim of this paper is to put forward a design model for multilayer free damping structures. It sets up a mathematical model and deduces the formula for its structural loss factor η and analyzes the change rules of η along with the change rate of the elastic modulus ratio q1, the change rate of the loss factors of damping materials q2, and the change rate of the layer thickness ratio q3 under the condition with the layer thickness ratio h2 = 1,3, 5,10 by software MATLAB. Based on three specific damping structures, the mathematical model is verified through ABAQUS. With the given structural loss factor (η ≥ 2) and the layer number (n = 3, 4,5, 6), 34 kinds of multilayer free damping structures are then presented. The study is meant to provide a more flexible and more diverse design solution for multilayer free damping structures.

Surface plasmon resonance (SPR) sensors are extensively employed for label-free, real-time monitoring of subtle refractive index variations at metal-dielectric interfaces, making them highly effective platforms for chemical and biochemical sensing. In this study, a numerically validated multilayer surface plasmon resonance (SPR) refractive index sensor is proposed composed of a silver (Ag) plasmonic layer integrated with methylammonium lead halide perovskite (MAPbX 3 ) and the low-dimensional material hafnium diselenide (HfSe 2 ) on a BK7 prism substrate. The hybrid heterostructure combines the excellent plasmonic characteristics of Ag, the variable optical absorption of MAPbX 3 , as well as the very high carrier mobility, and anisotropic optical characteristics of HfSe 2 to create greater confinement of the electromagnetic fields at the sensor interface. Electromagnetic modeling using the transfer matrix method and finite element simulations in COMSOL Multiphysics enabled optimization of layer thicknesses and evaluation of angular sensitivity, figure of merit (FOM), and detection limit. The Optimal Configuration is Ag: 56 nm; MAPbX 3 : 2.0 nm; HfSe 2 : 3.0 nm. This configuration provides an extremely high angular sensitivity of 320 ° /RIU at a wavelength of 633 nm. A strong linear relationship exists between resonance angle and refractive index variation within the range of 1.334 - 1.355 RIU (R 2 = 0.988). Machine learning models were employed to optimize computational efficiency and enable rapid prediction of sensor response, while maintaining a high level of accuracy (achieving an R 2 > 0.99). Electric field analysis confirms a maximum field strength of approximately 2.5 × 10 5 V/m when the angle of resonance is 76.6 ° as evidence of the strong plasmonic coupling in the multi-layer structure. Overall, the proposed design based on a perovskite-HfSe 2 heterostructure represents an adaptable, physics-based, high-sensitivity refractive index sensing platform for future chemically or biologically functionalized sensing applications.

Cavity enhancement of the magneto-optic Kerr effect in glass/Al/SnO 2/PtMnSb/SnO 2 structure

In the present work,a lithium niobate (LN) 43°Y cut LN filmis transferred onto a substrate with 11 layers of SiO2/Ta2O5 and solidly mounted resonators with a reflectorare successfully fabricated with the multilayer structure. The designmethod and fabrication process are demonstrated. The finite elementmodel and the Mason model are used. Scanning electron microscopy andatomic force microscopy are used to characterize film quality. Anoptimized design of a Bragg reflector to suppress the leakage of acousticenergy by thickness shear mode is proven to be effective. The influenceof the reflector on parasitic modes and filter out-of-band suppressionis analyzed. The resonator for 3.5 GHz shows an effective electromechanicalcoupling coefficient of 17.9%, and the figure of merit is 40.4, whichis suitable for band pass filter on the N78 band with high rejection.