A new equivalent -stepindex (E S I) method using the waveguide dispersion and modified spot size for obtaining the Gaussian deviation has been proposed. Numerical results for three different profiles have been obtained and discussed.

No abstract

The chemical surface structure in perovskite oxides has been identified by monitoring the oscillation intensity of reflection high energy electron diffraction patterns during initial growth of MO (M=Sr, Ba) films on the perovskite substrate. This successful analysis technique is demonstrated for the film growth on A and B-site oxides terminated ABO 3 substrates. Epitaxial growth of MO thin films is dominated by chemical interaction between the growing lattice and the underlying atomic layer to follow the crystal habit of forming a more stable layer unit cell. This simple technique can be used as a substitute to relevant physical techniques such as coaxial impact-collision ion scattering spectroscopy and friction force microscopy that are currently used techniques to determine the termination layer.

The geometric theory of Lie systems will be used to establish integrability conditions for several systems of differential equations, in particular Riccati equations and Ermakov systems. Many different integrability criteria in the literature will be analysed from this new perspective, and some applications in physics will be given.

An approach to optimization of a W single mode optical fiber, combining the Finite Element method (FEM), the Design of Experiments (DOE) method and the Sequential Quadratic Programming (SQP) method for constrained optimization, is presented. A global objective function (GOF) for multiresponse optimization is used, in which the partial objective functions (POP), i. e., the mode field diameters (MFDs), are multiplied by relevant weighting factors. The paper outlines the basic features of this approach, its advantages and its applicability in real practical work.