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Step-index profile
About: Step-index profile is a research topic. Over the lifetime, 3104 publications have been published within this topic receiving 53199 citations.
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TL;DR: In this article, a closed-form characteristic equation was derived from the variational formulation of the wave propagation in an optical fiber, provided that the permittivity in the core is proportional to r/sup alpha, where r is the radial coordinate and 1 < alpha < /spl infin/, and the cladding is uniform.
Abstract: This paper describes first that a simple closed-form characteristic equation can be derived from the variational formulation of the wave propagation in an optical fiber, provided that 1) the permittivity in the core is proportional to r/sup alpha/, where r is the radial coordinate and 1 < alpha < /spl infin/, and 2) the cladding is uniform. The obtained equation is then solved for various permittivity (or refractive-index) profiles. The results obtained are useful both for the understanding of the dispersion characteristics and for the design of inhomogeneous optical fibers. The optimum profile for a multimode fiber is derived and discussed
85 citations
Patent•
23 Sep 2002
TL;DR: In this paper, a non-contact, non-destructive measuring apparatus that measures thickness profile and refractive index distribution of a single or multiple layers of thin films by means of the principle of reflectometry is presented.
Abstract: The present invention relates to a non-contact, non-destructive measuring apparatus that measures thickness profile and refractive index distribution of a single or multiple layers of thin films by means of the principle of reflectometry. According to the present invention, by employing more than one narrow band-pass optical filters and a two-dimensional array of CCD sensors, and by finding an optimal solution for the nonlinear functional relationship between the thickness of said thin film or thin films and the corresponding refractive indexes by using an iterative numerical computation method, said apparatus simultaneously measures local area-wise thickness profile and refractive index distribution among others of said a single layer or multiple layers of thin films on a substrate.
84 citations
TL;DR: The dependence of the nonlinear refractive index n2 on glass compositions for optical fibers is clarified and the relation between n2 and germanium- or fluorine-doped SiO2 is calculated on the basis of the measurement of n2 at 1.55 μm with the improved cross-phase-modulation method.
Abstract: The dependence of the nonlinear refractive index n2 on glass compositions for optical fibers is clarified. The relation between n2 and germanium- or fluorine-doped SiO2 is calculated on the basis of the measurement of n2 at 1.55 μm with the improved cross-phase-modulation method, taking into account the radial distribution of the optical power in the fibers.
84 citations
TL;DR: In all cases, the variation in refractive index with increasing wavelength was found to be a smooth monotonically decreasing function that could be accurately fitted by the Cauchy formula.
Abstract: Refractive-index measurements of ten liquids were made at nine discrete wavelengths over the 589–1674-nm spectral range using a Hilger-Chance refractometer with a modified viewing system. The total error in refractive-index measurement was considered to be ±3 × 10−4. In all cases, the variation in refractive index with increasing wavelength was found to be a smooth monotonically decreasing function that could be accurately fitted by the Cauchy formula. Constants for the latter have been given.
84 citations
TL;DR: In this paper, the authors reported laser oscillation in what appears to be a single transverse mode with very large mode area in optical fibers having heavily Nd-doped 100μm diameter cores with refractive index significantly lower in the core than in the surrounding cladding.
Abstract: The authors report laser oscillation in what appears to be a single transverse mode with very large mode area in optical fibers having heavily Nd-doped 100μm diameter cores with refractive index significantly lower in the core than in the surrounding cladding. Since fibers of this type cannot support conventional index-guided modes, their results appear to confirm a recent analysis which predicts gain-guided single-mode propagation in index antiguided fibers, provided the gain coefficient in the core exceeds a threshold value. Fibers of this type may be of significant interest for amplifiers and oscillators having large power outputs and/or small nonlinear pulse distortion.
82 citations