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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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Journal ArticleDOI
TL;DR: In this article, an optical fiber, partially stripped of its cladding is shown to sense refractive index of a liquid in which the uncladded sensing region is immersed, to a high degree of precision and over a wide range of refractive indices.
Abstract: An optical fiber, partially stripped of its cladding is shown to sense refractive index of a liquid in which the uncladded sensing region is immersed, to a high degree of precision and over a wide range of refractive index. The slope of sensor response is found to be non linear, can have either sign and can change sign at around refractive index of the fiber. The sensitivity of the sensor to refractive index change is dependent on cladding thickness and is a maximum at an intermediate thickness value. It is insensitive to the presence of absorption at the wavelength at which refractive index is being measured and to the chemical nature of the solute. Experiments designed to show that cladding modes are responsible for sensing are described.

109 citations

Journal ArticleDOI
TL;DR: In this paper, the dispersion of a sample of commoner gases has been determined with some accuracy by measuring the refraction for different wave-lengths, and the dielectric coefficient at different temperatures.
Abstract: In recent years, values of the refractive index of liquids, and sometimes of gases, have been extensively used for determining dipole-moments. Measurements of dielectric coefficients give the sum of the orientation, electronic and atomic polarizations P + Pe +Pa, while the electronic polarization Pe can be calculated approximately from the refractive index. If the dispersion is known, Pe should be given with some accuracy by calculating the refractive index at zero frequency. In order to obtain P, it is necessary to know Pa, a quantity which has only been determined for a few substances, the infra-red spectrum of which has been examined in detail. It is, however, often assumed that Pa is negligible or, at least, small in comparison with Pe. In some cases, an approximation on an empirical basis has been made by assuming that Pa is proportional to Pe, or that Pa + Pe is equal to the value of Pe when calculated from the refractive index for the yellow sodium line. Such assumptions can hardly be regarded as satisfactory. In liquids, determination of the polarization is complicated by the necessity of employing a solvent, but, with gases, no such difficulty exists. Pa can therefore be determined with some accuracy by measuring the refraction for different wave-lengths, and the dielectric coefficient at different temperatures. Numerous measurements of the refractive index of the commoner gases have been made, but the results of different observers are not always in agreement and frequently the dispersion has not been determined. The dielectric coefficient of the same sample of gas seems never to have been measured.

107 citations

Journal ArticleDOI
James William Fleming1
TL;DR: In this article, material and mode dispersion in fibers made from glasses in the system GeO2-B2O,3-SiO2 have been calculated using refractive index dispersion results for these glasses.
Abstract: Material and mode dispersion in fibers made from glasses in the system GeO2-B2O,3-SiO2 have been calculated using refractive index dispersion results for these glasses. Refractive indices were measured on bulk glass specimens using the minimum deviation method at wavelengths from 0.4358 to 1.0830 μm. The resultant data were then fitted to a 3-term Sellmeier dispersion relation for each glass composition. The fitted equations and a recent theory on the relation of the optimum index profile in a graded index optical waveguide to pulse dispersion were used to calculate the exponent α, which characterizes the shape of the profile, for several practical fiber models. The most effective profile shape for reducing pulse dispersion is a function of wavelength, composition, and fictive temperature. The present data were used elsewhere to predict accurately the optimum profile for minimization of pulse dispersion in several fiber systems consisting of germanium borosilicate glasses.

107 citations

Journal ArticleDOI
TL;DR: In this paper, a periodic array of gold nanorod pairs demonstrate its unique optical properties, including a negative refractive index in the optical range, which is the first known property of a gold nanoprocessor.
Abstract: Comprehensive studies for a periodic array of gold nanorod pairs demonstrate its unique optical properties, including a negative refractive index in the optical range.

107 citations

Patent
16 Feb 1994
TL;DR: In this article, a power law core refractive index profile is proposed for the optical fiber that can advantageously be used to compensate chromatic dispersion in an optical fiber communication system, typically a system that is upgraded from 1.3 μm to 1.55 μm operating wavelength.
Abstract: Disclosed is optical fiber that can advantageously be used to compensate chromatic dispersion in an optical fiber communication system, typically a system that is upgraded from 1.3 μm to 1.55 μm operating wavelength (λ op ). The fiber typically has a power law core refractive index profile, a refractive index "trench" surrounding the core, and a refractive index "ridge" surrounding the trench. The refractive index profile of the fiber preferably is designed such that the fiber supports the fundamental mode (LP 01 ), does not support the LP 11 mode but does support the LP 02 mode, all at λ op . At λ op , LP 01 has dispersion more negative than -150 ps/nm·km and, in a preferred embodiment, LP 01 also has negative dispersion slope at λ op . In a further embodiment of the invention the refractive index profile is designed such that the cut-off wavelength of the LP 11 mode is less than that of the higher order mode, typically LP 02 , and less than λ op , such that the fiber does not support propagation of the LP 11 mode. In some preferred embodiments the fiber is designed to have dispersion more negative than about -90 ps/nm·km and loss less than about 0.5 dB/km at λ op ˜1.55 μm.

107 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202318
202236
20219
202011
201913
201814