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In this study, we investigate acoustic wave propagation in 3 D phononic crystal (PnC) slabs wherein scatterers have different cross sections by using the finite-element method. The PnC consists of scatterers embedded in the host material arranged in a square lattice and honeycomb lattice in different patterns (bathroom and ladybug tiling in Archimedean-like tiling). By determining the eigenmodes and band gaps, complete and accurate band structures and transmission spectra are obtained. Compared to traditional square lattice PnCs, it has been observed that the bands obtained in pattern structures may have some advantages in terms of width and position. It was also shown that the low-frequency response of two Archimedean-like structures was similar with respect to the traditional square lattice.

The goal of the work presented in this investigation is to achieve the efficient parametric interaction of narrow beams (in particular second harmonic generation) using a nonlinear (ferroelectric-LiTaO3) photonic crystal tuned to self-collimation (nondiffractive) regimes. A numerical study of second harmonic generation (SHG) in one-dimensional nonlinear photonic crystals based on a full nonlinear system of equations, implemented by a combination of the method of finite elements and fixed-point iterations, is reported. This model is derived from a nonlinear system of Maxwell’s equations that partly overcomes the known shortcoming of some existing models that rely on the undepleted pump approximation. We derive a general solution of SHG in one-dimensional nonlinear photonic crystals structures. Numerical simulations also show that the conversion efficiency of SHG can be significantly enhanced when the frequencies of the fundamental wave are located at the photonic band edges or are assigned to the designed defect states.

In this report, we present an investigation of the dispersion properties of the phononic crystal in different lattice, geometries for various piezoelectric materials. We study dispersion pr...

In this study, the band structure and transmission spectra in multiferroic based Sierpinski-carpet phononic crystal are investigated based on finite element simulation. In order to obtain the band structure of the phononic crystal (PnC), the Floquet periodicity conditions were applied to the sides of unit cell. The square lattice PnC consists of various piezoelectric inclusion in a rubber matrix with circular and triangular cross section.

Temporally periodic photonic crystals develop an ω-k dispersion relation with momentum band gaps. While conventional photonic crystals induce forbidden bands in the frequency spectrum of photons, photonic time crystals create forbidden regions in the momentum spectrum of photons. This effect allows for enhanced control over many optical processes that require both photonic energy and momentum conservations such as nonlinear harmonic generation. The simulation results show that more intensive scatter fields can obtained in photonic space time crystal. Also, we investigate topological phase transitions of photonic time crystals systems.

In the present work the acoustic band structure of a two-dimensional phononic crystal containing an organic ferroelectric (PVDF- polyvinylidene fluoride) and muliferroic material (LiVCuO4) were investigated by the plane-wave-expansion method. A two-dimensional PC with square lattices composed of LiVCuO4 cylindrical rods embedded in the PVDF matrix are studied to find the existence of stop bands for the waves of certain energy. This phononic bandgap - forbidden frequency range - allows sound to be controlled in many useful ways in structures that can act as sonic filters, waveguides or resonant cavities. Phononic band diagram omega = omega(k) for a 2D PC, in which non-dimensional frequencies omega a/2 pi c (c-velocity of wave) were plotted versus the wavevector k along the Gamma-X-M-Gamma path in the square Brillouin zone show four stop bands in the frequency range 0.01-8.0 kHz. The ferroelectric properties of PVDF and unusual properties of multiferroic LiVCuO4 give us the ability to control the wave propagation through the PC in over a wide frequency range.

In the present work, the acoustic band structure of a two-dimensional (2D) phononic crystal containing a multiferroic and liquid were investigated by the plane-wave-expansion method. 2D PnC with triangular and honeycomb lattices composed of LiCu2O4 cylindrical rods embedded in the seawater matrix are studied to find the existence of stop bands for the waves of certain energy. Phononic band diagram ω=ω(k) for a 2D PC, in which nondimensional frequencies ωa/2πc (c-velocity of wave) were plotted versus the wavevector k along the г-X-M-г path in the Brillouin zone show few stop bands in the frequency range between 10 and 110 kHz.

This paper presents the design, modeling and finite element model simulation of a micro-electromechanical system based on the ternary ferroelectric compounds and paratellurite. The dynamic behavior of the sensor structure is described by the super position of its dominant vibration mode shapes. The resulting model still considers all the physical domains and is even able to capture nonlinear phenomena, such as the stress stiffening of constraint structures or frequency and stiffening caused by squeezed gas in the sensor cell. Process induced and thermally induced residual stresses and the resulting deformation of the transducer elements are considered. © 2016, © Taylor & Francis Group, LLC.

This paper presents the design and modeling of micro-electromechanical systems (MEMS) on the ternary ferroelectric compounds (PZT) based by using finite element model (FEM) simulation. The conceptual framework establishes five steps to perform the critical analysis: design a novel structure, define the failure mechanisms under the given conditions, analyze different vibrations, analyze the operation principle, and detect resonance modes. In addition, MEMS failure modes were analyzed under different scenarios and the obtained results discussed. Copyright © Taylor & Francis Group, LLC.