Abstract
The purpose of the present work is to construct a reaction board based on fiber Bragg gratings (FBGs) that could be used for estimation of the 2D coordinates of the projection of center of gravity (CG) of an object. The apparatus is consisted of a rigid equilateral triangular board mounted on three supports at the vertices, two of which have cantilevers instrumented with FBGs. When an object of known weight is placed on the board, the bending strain of the cantilevers is measured by a proportional wavelength shift of the FBGs. Applying the equilibrium conditions of a rigid body and proper calibration procedures, the wavelength shift is used to estimate the vertical reaction forces and moments of force at the supports and the coordinates of the object's CG projection on the board. This method can be used on a regular basis to estimate the CG of the human body or objects with complex geometry and density distribution. An example is provided for the estimation of the CG projection coordinates of two orthopaedic femur bone models, one intact, and the other with a hip stem implant encased. The clinical implications of changing the normal CG location by means of a prosthesis have been discussed.

Abstract
A review in fiber post-processing for sensing applications is presented. The review is divided in three parts. Tapers devices, chemical etching for Fabry-Perot cavities and focused ion beam (FIB) as post-processing applied in optical fibers are considered. The most recent results as sensing elements are shown. © 2014 OSA.

Abstract
Distributed grating coupling of light pulses into planar waveguides, exhibiting third-order nonlinear-optical effects, is studied theoretically. The nonlinear interaction taking place between a beam that is Gaussian in time and space and one or more waveguide media with intensity-dependent refractive indexes or absorptions is analyzed, with emphasis on the different effects that result from the relative importance of two-photon absorption, dispersive index changes, and their saturation. Criteria for the evaluation of real and imaginary parts of chi-(3) by means of grating coupling are outlined.

Abstract
We report on the experimental evaluation of the intensity-dependent index of refraction of a new family of polymers, using guided-wave techniques. The materials are 'DANx-polymers', and the measurements were performed at 1.064 µm with 30 ps pulses employing nonlinear distributed grating coupling into spin coated planar waveguides. The analysis shows large electronic and nonresonant n2 coefficients. The examined materials have outstanding potentialities for all-optical signal processing in an integrated optics format.

Abstract
Optical third harmonic generation at 1.904, 1.579 and 1.064 µm experiments have been performed on thin films fabricated from side chain polymers containing effectively 4-dialkylamino-nitro-benzene, 4-dialkylamino-4'-nitro-stilbene, 4-dialkylamino-4'-nitro-diphenylbutadiene, 4-dialkylamino-4'-nitro-diphenylhexatriene as the side groups. We have measured values of ?(3) (-3?; ?, ?, ?) in the range of 0.54 × 10-12 to 7.42 × 10-12 esu, at 1.904 µm incident radiation, which are comparable to the nonresonant values found in fully conjugated back-bone polymers [1]. The values of ?(3) at both 1.904 and 1.579 µm change by a factor of 15 as the conjugation length is increased. © 1990.

Abstract
Nonlinear optical properties of conjugated polymers can be measured using various techniques, including third-harmonic generation, two-photon absorption, nonlinear grating coupling and interferometry. These methods will be compared with regard to their suitability for obtaining specific parameters. We illustrate the application of these techniques to the study of pi-conjugated polymeric systems, such as poly(4-BCMU), poly(3-decyl-thiophene) and 4-dialkylamino-4'-nitrostilbene (DANS) side-chain polymer, all of them regarded as candidates for the realization of all-optical switching devices, and outline relevance and limits of each technique.