Abstract
We describe and demonstrate a new hybrid current sensor system which uses a novel time division multiplexed fiber network for the measurement of three-phase currents at high potential. The sensor arrangement combines a conventional current transformer with a fiber-optic interferometer such that the signal is transmitted optically to ground. Sensitivities of ~0.5 A/vHz are obtained in each phase at the line frequency of 50 Hz. The sensitivity and dynamic range of each sensor can be tailored for a specific level of current or according to an individual application.

Abstract
A detailed comparison between a low-finesse Fabry-Perot cavity and a typical two-beam interferometer is developed and checked experimentally. The consequences of approximating the true Fabry-Perot function by the two-beam function are evaluated for commonly used signal-processing schemes in order to quantify the final error introduced in various fiber sensing schemes employing this configuration.

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.

Abstract

Abstract
We investigate the third-order nonlinearity of DANS and DAN2 side-chain polymers by tunable third-harmonic generation and nonlinear distributed coupling. The large third-order susceptibility can be interpreted in terms of microscopic cascading of second-order hyperpolarizabilities.

Abstract
A scheme to frequency multiplex a group of sensors based on all-fiber Michelson interferometers is presented. Lead insensitivity is obtained by using the two fiber leads of the configuration as an extra Michelson interferometer whose differential phase is kept constant by active compensation. Topics concerning the system design, sensor sensitivity, and crosstalk between sensors are investigated. Experimental and numerical computational results are presented.