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The field equations governing the plane harmonic elastic motions of anisotropic stratified media are written in the form of a matrix system of differential equations, where the dependent variables are the displacements and tractions acting across planes normal to the direction of stratification. In the case of periodically layered media, Floquet’s theorem and the propagator matrix method can be applied to solve the governing sextic matrix equation. In the absence of sources or body forces, the general motion of the layered medium is described by a combination of six partial waves (Floquet waves). A closed-form algebraic solution for the dispersion equation of such waves is derived. Numerical results describing the dispersion spectrum of a cross-ply periodic laminated are discussed in detail.

In this article we introduce a systematic methodology to investigate wave propagation in piezoelectric layered media. It is based on a matrix formalism and the con cept of the surface impedance tensor which relates the components of particle displace ment and the normal component of the electric displacement along a surface to the electric potential and the components of traction acting along the same surface. Once the surface impedance tensor for a single layer is calculated, a simple recursive algorithm allows the evaluation of the surface impedance tensor for any number of layers. As an example, the surface impedance tensor is used to find the dispersion curves for a bilaminated piezoelec tric plate. Also the dispersion curves for the subsonic interfacial waves when the plate is in contact with a nonconducting acoustic fluid is investigated. Floquet theory is also ap plied to study wave propagation when the layered medium is periodic.

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In this paper we discuss the results obtained with an in-fiber Fabry-Perot interferometer (FPI) used in strain and magnetic field (or force) sensing. The intrinsic FPI was constructed by splicing a small section of a capillary optical fiber between two pieces of standard telecommunication fiber. The sensor was built by attaching the FPI to a magnetostrictive alloy in one configuration and also by attaching the FPI to a small magnet in another. Our sensors were found to be over 4 times more sensitive to magnetic fields and around 10 times less sensitive to temperature when compared to sensors constructed with Fiber Bragg Grating (FBG).