الفهرس 
Introduction
Two and multiple -beam interferometryOnly 14 pages are availabe for public view
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Abstract
The theory of measurements of the refractive index profiles n(r) of optical fibres utilizing using the multiple beam fringes and the twobeam fringes methods are described in details in chapter I. In this chapter two methods for measuring the refractive index profiles of the optical fibres are presented. The first method used is the interference fringe shift to measure the refractive index profile n(r). The second method used when the fibre under study has irregular transverse sectional shape, the area enclosed under the fringe shift is considered to represent the optical path difference integrated across the whole cross sectional area of the fibre. This method is more suitable for determining its refractive index profile n(r) of this fibre. In chapter II the corecladding refractive index difference (SE(Bn and the index gradient profile parameter ga sof the graded index optical fibre has been determined. The optical path difference ((Se? (Bcan be determined using the interference pattern. The optical path difference ((Se? (Bis determined by analyzing the microinterferogram. The curve representing the real path due to refraction of the beam, in the core region is considered. Multiple beam Fizeau fringes and two beam interference Pluta polarizing interference microscope is used for this investigation. A new method based on the proposed theory is used with a prepared computer program, to estimate the fringe shift. The estimated and experimental values of the fringe shift, along the core radius are used to obtain the refractive index profile of the optical fibre. The fabrication method and theory of measurements of the refractive index profiles of the waveguides fabricated by UVexcimer laser is described in details in chapter III. Two beam interference MachZehnder technique is used to measure these profiles. In this method we used the interference fringe shifts to measure the refractive index profile n(r) against the depth. In chapter IV the refractive index profiles of the waveguides fabricated by UVexcimer laser at different doses has been determined. The optical path difference ((Se? (Bcan be determined using the interferograms. The optical path difference ((Se? (Bis determined by analyzing the magnified pattern. The curves representing the refractive index profiles from the photochemical reaction point of view is considered. A suggested method based on the proposed theory is used. The experimental values of the fringe shift, along the depth, are used to obtain the refractive index profile of the waveguide. Microinterferograms are given for illustrations. In chapter V the fitting functions of the refractive index profiles of the waveguides fabricated by UVexcimer laser at different doses have been determined. These functions are exponential functions for some samples and gaussian functions for other samples. We used here two models; the first one represents the exact solution for waveguides which have exponential profiles. The electric field distribution for the modes resulted has been determined. The second model is a numerical solution for waveguides, which have a gaussian profile. The WKB approximation, which used in quantum mechanics, is used here. The modes numbers have been determined in both cases. In chapter VI the refractive indices profiles of the waveguide fabricated by UVexcimer laser at different doses (fluence = 100 mJ/cm2) have been determined. The first region fitted by a polynomial function while the second region fitted by gaussian function. The modes analyses for the two regions have been performed. The field distribution for every mode for each sample has been determined.