Propagation of acoustic wave’s motion in orthotropic Cylinders of infinite length

We report, in the present work, a numerical method for investigating guided waves propagation in a homogeneous infinite cylinder composed of elastic material. This method makes use of Legendre polynomials series and harmonic function to express different displacement components which are introduced into the equation of motion. The advantage of this method is the possibility to incorporate the stress-free boundary conditions directly into the equations of motion by assuming position-dependent elastic constants and mass density. The solution of the wave equations can be reduced to an eigenvalue problem. Numerical results are presented and compared with those published earlier in order to validate our polynomial approach. For certain specific modes, dispersion curves and field profiles such as mechanical displacements, normal stresses are presented. The developed software is capable of dealing efficiently and accurately with a variety of homogeneous and inhomogeneous cylinders

Acoustically driven storage of light in a quantum well

The strong piezoelectric fields accompanying a surface acoustic wave on a semiconductor quantum well structure are employed to dissociate optically generated excitons and efficiently trap the created electron hole pairs in the moving lateral potential superlattice of the sound wave. The resulting spatial separation of the photogenerated ambipolar charges leads to an increase of the radiative lifetime by orders of magnitude as compared to the unperturbed excitons. External and deliberate screening of the lateral piezoelectric fields triggers radiative recombination after very long storage times at a remote location on the sample.Comment: 4 PostScript figures included, Physical Review Letters, in pres

MODULATEURS ACOUSTO-OPTIQUES À PUITS QUANTIQUES MULTIPLES

GaAsIAlGaAs Multiple Quantum Well acoustooptic modulator is presented. The method of the device analysis is proposed SAW induced elechic field magnitudes and the absorption coefficient are calculated

Mapped orthogonal functions method applied to acoustic waves-based devices

This work presents the modelling of acoustic wave-based devices of various geometries through a mapped orthogonal functions method. A specificity of the method, namely the automatic incorporation of boundary conditions into equations of motion through position-dependent physical constants, is presented in detail. Formulations are given for two classes of problems: (i) problems with guided mode propagation and (ii) problems with stationary waves. The method’s interest is demonstrated by several examples, a seven-layered plate, a 2D rectangular resonator and a 3D cylindrical resonator, showing how it is easy to obtain either dispersion curves and field profiles for devices with guided mode propagation or electrical response for devices with stationary waves. Extensions and possible further developments are also given