International Journal of Modern Physics B

Photonic Crystal Fiber (PCF) constructions, controlled light propagation for measuring amplitude, phase, polarization and wavelength of the spectrum, and PCF-incorporated interferometry techniques are the foundations upon which sensors operate. But the existing PCF techniques have very large stretching that tends to be difficult to align due to the cross-polarization mode of the optical fiber structure. Hence, the novel Polymer graphene-based Hexagonal cladding is designed by using a hexagonal hollowed core and a cladding material of Polymethyl methacrylate reinforced with gyroidal graphene which increases confinement strength. Once the crystal structure is designed, normally the presence of substrate the Q-factors is degraded. On substrates, Q-factors are enhanced by fine-tuning the position of the neighboring holes. Hence, the novel Bilayer Grating Stratum solves the degrading issues in Q-factors, which utilizes a Silicon polyamide-coated FBG in the crystal that is incorporated using the Femto-laser technique thereby increasing the wavelength tenability. To identify the electric field pattern, the designed structure is simulated in COMSOL software. Thus, the proposed system has a high sensitivity of 22 with a low material loss of 0.1% and a low response time of 0.2s.

This work focuses on the electrical transport and conduction mechanisms — inside a sprayed — made zinc oxide-on-p-type silicon junction device. A fabricated Al/ZnO/Si/Al heterojunction is characterized at 300 and 380K in the dark. The aforementioned theories predict that the current density (J) is an exponential function of measured voltage (V) and work temperature (T). Exponential equations are linearized as a result of a current conduction mechanism (CCM) kind. Useful parameters like barrier height ${\phi }_t$ of trap are extracted from the slope B. Ohmic and space charge limited current (SCLC) regimes inside are studied at 300 and 380K recording a shift in exponent as a result of temperature. Fowler–Nordheim (FN) conduction mechanism inside Al/ZnO/Si/Al device is considered slope and ${\varphi }_b$ values are determined for two cited work temperatures. Our device presents a thermionic emission (TE) and exhibits an effect of temperature on slope and intercept values of (ln$J_{TE}$/A*$T^2$) function. The Poole–Frenkel (PF) emission in terms of 1/V data are presented for 300 and 380K. Besides, PF emission mechanism in terms of 1/$T^2$ is exhibited and parameters are influenced by temperature. Behavior of conductance as a result of temperature is detailed and evidenced.

In this paper, the multi-objective optimization problem (MOOP) of selecting suitable materials from four materials for phononic crystals layouts is investigated based on an optimization method combined nondominated sorting-based genetic algorithm II (NSGA-II) and finite element method (FEM). Driven by different optimization objectives, the changes in the optimized structure compared to the seed structure are the change of the bandgap mechanism from a local resonance mechanism to a Bragg scattering mechanism, the change of the included materials from four to three, and the significant change in the location and extent of the pores and other materials, respectively. The obtained nondominated Pareto solution of MOOP can balance the bandgap and the structural mass, which provides the decision-maker trade-off to select the appropriate optimized solution. Compared with the single-objective optimization problem (SOOP), the MOOP not only obtains a nondominated solution close to the result of SOOP, but also obtains other nondominated solutions of MOOP, which proves the effectiveness of the optimization algorithm in this paper. The design method in this paper can be easily extended to select suitable materials from a wider variety of materials for bandgap optimization design of PnCs, which has very promising applications.

Acoustic black hole (ABH) is a technique capable of manipulating the propagation of flexural wave, and the sonic black hole (SBH) is a kind of ABH which is used to manipulate sound wave in a fluid medium. In this paper, we propose an SBH structure with labyrinthine units and combine with micro-perforated panel (MPP) to form a composite sound absorption structure. The sound absorption mechanism of the absorption structure is deeply investigated using numerical and simulation methods. The simulation reveals the sound absorption mechanism by acoustic streaming effects of composite sound absorption structure. We analyze the flow characteristics of the acoustic medium under acoustic excitation, and the effect of the flow field on the distribution of the acoustic field, and the energy dissipation distribution. Our theoretical results show that the sound absorption is attributed to the effects of sound energy focusing of ABH, the local resonance of MPP, and the acoustic energy localization and dissipation effect of labyrinthine units caused by large flow velocity gradients. Finally, the proposed composite sound absorption structure has good sound absorption performance, which is also confirmed by impedance tube experiments. It can provide a new way of thinking for the design and optimization of the SBH structure.

Based on density functional theory, structural, electronic, magneto-optic, and thermoelectric properties of RbCaN₂ and RbCaO₂, Heuslerene compounds have been calculated. These compounds have the ground state points with total magnetic moment of 1.0${\mu }_B$, which represents their ferromagnetic behavior. The RbCaN₂ Heuslerene has the half-metallic nature and RbCaO₂ case is a magnetic semiconductor. The Kerr angle of the RbCaN₂ Heuslerene has two relatively peaks at the energies of 5.5eV to 7.0eV, but for the RbCaO₂ compound, this diagram is wider in a larger energy range. Faraday angle peaks occurred at 6.2eV and 6.8eV for RbCaN₂ and RbCaO₂ compounds, which indicates the polarization of the light irradiated to them at these energies. It was observed that both compounds show high thermoelectric quality at temperatures higher than the room-temperature, and both compounds are suitable for power generator applications.

An asymmetric system consisting of two coupled radio frequency superconducting quantum interference devices (RF-SQUIDs) with general geometry as nonlinear macroscopic system with mutual inductance under the influence of a time-dependent external field has been investigated numerically. Due to the importance of mutual induction in the construction of such nonlinear asymmetric systems, the dependence of coupling coefficient on the frequency changes, the primary and secondary resonance amplitudes and also the anti-resonances in both squids have been investigated. By changing the geometry of the arrangement of squids, the dynamic behavior parameters of the system have been studied. The eigenvalues of this system have been found and by changing frequency, the stable and unstable states have been studied.

In this paper, the thin-film ferroelectric material equation (TFFME) which enables the propagation of solitary polarization in thin-film ferroelectric materials is investigated, and also illustrated through the nonlinear evolution equations. Ferroelectrics are dielectric materials that exhibit nonlinear behaviors in wave propagation. Thin films constructed from the ferroelectric materials are utilized in different modern electronic devices. To investigate the characteristics of new waves, the solitary wave dynamics of the mentioned equation is used in the generalized trial equation scheme. The bright and periodic solutions are obtained by semi-inverse variational principle scheme. Many alternative responses may be obtained through different formulae; each of these solutions offers a distinct graph. The validity of such methods and solutions may be demonstrated by assessing how well the relevant techniques and solutions match up. The effects of free variables on the behavior of few achieved solutions for nonlinear rational exact cases are also plotted and explored depending upon the nature of nonlinearities. The dynamic properties of the obtained results are shown and analyzed by some density, two- and three-dimensional images. The results provide a way for future research on generating optical memories based on the nonlinear solitons.

The squeezing and statistical features of the intracavity field produced by a three-level laser coupled to a vacuum reservoir with input coherent field are studied in this paper. Employing the propagator method, we determine the Q-function for the cavity field produced by a driven three-level laser. Using this Q-function, we have calculated the mean intensity, the quadrature variance, and the squeezing spectrum of the cavity field. It has been discovered that, despite the fact that the input coherent field improves the mean intensity of the cavity field, it has no effect on the quadrature squeezing of the cavity field. The degree of squeezing increases with the rate at which atoms are injected into a cavity and a substantial degree of squeezing is found close to the maximum initial injected atomic coherence.

In solid-state systems, spin squeezing states have acquired much interest in quantum information processing since they are not only essential from a basic physics standpoint but also have many applications, notably reducing noise in interferometry. This paper addresses the study of quantum nonlocality as examined by the violation of the Bell and Clauser–Horne–Shimony–Holt (CHSH) inequality in two classes of spin squeezing states and how this relates to the quantum-memory-assisted entropic uncertainty relation (QMA–EUR). The spin squeezing states in the two classes are systematically generated by two twisting nonlinear interactions. These separately describe two spin-$\frac{1}{2}$ interaction mechanisms that undergo one-axis twisting (OAT) and two-axis countertwisting (TAC). We investigate each spin squeezing mechanism in a thermal bath ($k_{B}T$) with a transverse magnetic field. Our main results indicate that the degree of violation of the Bell-CHSH inequality and the entropic uncertainty relation (EUR) is typically anticorrelated in both mechanisms. We demonstrate that the spin squeezing states in the OAT mechanism violate the Bell-CHSH inequality and thus exhibit Bell nonlocality only at low temperatures ($k_{B}T\to 0$), whereas in the TAC mechanism, increasing the strength of the spin squeezing interaction leads to a violation of the Bell-CHSH inequality even at finite temperatures. We have also shown that there is always an expansion of the EUR and a decrease in the degree of violation of the Bell-CHSH inequality in the high-temperature regime. In addition, the transverse magnetic field exhibits different behavior under the considered temperature regimes in the two classes of spin squeezing states. Other results will also be discussed.

We consider two recent solutions of the generalized Faddeev–Volkov model, which is an exactly solvable Ising-type lattice spin model. The first solution is obtained by using the noncompact quantum dilogarithm, and the second one is constructed in a recent study via the gauge/YBE correspondence. We show that the weight functions of these models obtained by different techniques are the same upto a constant.

Nanotwin strengthening mechanism has been successfully applied to a variety of metallic materials. The strengthening originates from the hindering effect of twin-boundary (TB) on dislocations, and the formation of twin is greatly determined by the magnitude of the TB energy (TBE). In this work, the TBEs of three face-centered-cubic (FCC) metals were calculated by first-principles, the effect of the supercell size (the TB spacing and TB area) on the TBE was investigated, and the relationship between the TBE and the twinning formation mechanism was discussed. The results show that the TBEs calculated in this paper are in good agreement with the experimental values. Meanwhile, the magnitude of the TBE explains reasonably the twinning formation ability of these FCC metals in experiments.

A numerical algorithm based on the probabilistic path integral approach for solving Schrödinger equation has been devised to treat molecular systems without Born–Oppenheimer approximation in the nonrelativistic limit at zero temperature as an alternative to conventional variational and perturbation methods. Using high-quality variational trial functions and path integral method based on generalized Feynman–Kac method, we have been able to calculate the non-Born–Oppenheimer energy for hydrogen molecule for the $X^1{\mathrm{\Sigma }}_g^1$ state and hydrogen molecular ion. Combining these values and the value for ionization potential for atomic hydrogen, the dissociation energy and ionization potential for hydrogen molecules have been determined to be 36 113.672(3)cm${}^{-1}$ and 124 446.066(10)cm${}^{-1}$, respectively. Our results favorably compare with other theoretical and experimental results and thus show the promise of being a nonperturbative alternative for testing fundamental physical theories.

In the existing investigation, impacts of slip and chemical reactions on mass and heat exchange on an incompressible and electrically conducting micropolar fluid past a porous wedge within the sight of Hall and ion slip are examined. By employing similarity conversion, the relevant highly nonlinear PDEs are reformed into a collection of nonlinear linked ODEs. The equations framed in this manner have been resolved by using the bvp5c, the in-build MATLAB. Examination of magneto-hydrodynamic micropolar fluid on stagnation point flow is significant due to its uses in the production of plastic substances, polymer extrusion, lubricants, etc. The influence of the magnetic field, heat generation, microrotation, along with Hall and ion slip on the liquid flow is analyzed. Examination with prior published research papers is performed and the outcomes are compared with each other. Numerical simulations for shear stress coefficients, Sherwood and Nusselt numbers are provided in tabular form, and in addition, the variations in axial and microrotation velocities, temperature and solutal profiles are evaluated visually for various parameters in detail. The ion slip and slip velocity both slow down the shear rate, whereas the elevated values of the Hall and magnetic parameters show an opposite trend. The profile shows thinning of the bounding surface and offers its greatest magnitude in the case of a Newtonian liquid.

With a classical trajectory Monte Carlo model, we systematically study the laser intensity and field amplitude ratio dependence of nonsequential double ionization by counter-rotating two-color circularly polarized fields (800 and 1600nm). The results show that the optimized field amplitude ratio changes with the laser intensity, which is attributed to the shift of the most probable amplitude ratio of electron returning with the laser intensity. Moreover, the laser intensity-dependent double ionization probability curve shows a remarkable dip in the transition region between the nonsequential and sequential channels. It can be well explained by the reduction of the probability of electron returning with the increase of the laser intensity.

In view of the problem of heavy weight of the low-frequency band metamaterial absorber, the weight of the metamaterial absorber is mainly concentrated in the medium dielectric substrate. Different from the previous metamaterial absorbers based on continuous dielectric substrate, a new lightweight metamaterial absorber based on discontinuous dielectric medium is proposed and verified in the L-band (1–2GHz). Compared with metamaterial absorber based on the continuous dielectric substrate, the weight of the metamaterial absorber designed based on discontinuous media is reduced by 42.58%. The dual-peak reflection losses of −17.29dB and −15.99dB are obtained at 1.23GHz and 1.72GHz, respectively. Our work provides a new method for constructing light dual-peak metamaterial absorbers in the L-band.