Abstract
An investigation is performed of the characteristics of the self-referencing intensity based Q-type fibre optic sensor using a recirculation loop structure. Both transmissive and reflective configurations are analysed. Via the definition of the measurement parameter (the R parameter) the linearity and sensitivity of the sensor are addressed. Theoretical and experimental results are compared, considering the problem of sensor design and optimization.

Abstract

Abstract
Faraday rotator mirror elements have been used in a number of applications as compensators for induced birefringence in retracing paths. In interferometric systems, such as the fiber-optic Michelson interferometer, this approach proved to be useful in providing maximum fringe visibility and insensitivity to the polarization state of light injected into the interferometer. However, it is found that, when the characteristics of the fiber coupler depend on the polarization state of the input beam, the efficiency of the Faraday mirror elements is limited. Theoretical analysis and experimental results in support of this statement are presented.

Abstract
A theory based on the Kukhtarev-Vinetskii model is developed that provides the evolution equation of one-dimensional optical spatial solitons in photorefractive media. In the steady-state regime and under appropriate external bias conditions, our analysis indicates that the underlying wave equation can exhibit bright and dark as well as gray spatial soliton states. The characteristics of these self-trapped optical beams are discussed in detail. (C) 1995 Optical Society of America

Abstract
The self-bending process of steady-state bright spatial solitons in biased photorefractive media is investigated by taking into account diffusion effects. By integrating numerically the nonlinear propagation equation, it is found that the soliton beam evolution is approximately adiabatic. The self-deflection process is further studied using perturbation analysis, which predicts that the center of the optical beam moves on a parabolic trajectory and, moreover, that the central spatial frequency component shifts linearly with the propagation distance. Relevant examples are provided.

Abstract
We derive vector soliton solutions for photorefractive media in which the refractive-index perturbations must be treated as tensors. The two polarizations of the vector solitons may be coupled through the space-charge field alone and/or through cross terms in the electro-optic tenser, which requires phase matching and specific configurations. We analyze bright planar vector solitons and verify their stability. (C) 1995 Optical Society of America