Showing papers on "Step-index profile published in 1975"
TL;DR: Several methods that measure the refractive index pro file of a graded index fiber have been reported: an interferometric method, a far-field pattern meth od, and an electron beam microprobe method.
Abstract: Several methods that measure the refractive index pro file of a graded index fiber have been reported: for examFig. 1. The off-axis ray's path in an inhomogeneous medium. ple, an interferometric method, a far-field pattern meth od, and an electron beam microprobe method. This Let ter reports a simple and accurate reflection method. The reflected power from the surface of the sample is di rectly related to the refractive index of the sample. In the case of normal incidence, the reflectivity R is given as
74 citations
TL;DR: In this article, an interferometric method in conjunction with Abel inversion is used to precisely measure the index of refraction profile of clad optical fibers without perturbing them, and the sample is immersed in index matching fluid, so that fiber index variations cause only small phase shifts for rays propagating perpendicular to the axis.
Abstract: An interferometric method in conjunction with Abel inversion is used to precisely measure the index of refraction profile of clad optical fibers without perturbing them. The sample is immersed in index‐matching fluid, so that fiber index variations cause only small phase shifts for rays propagating perpendicular to the axis, making interferometric methods applicable.
64 citations
TL;DR: In this paper, a method for measuring the refractive index profile of optical glass fibres is described, which simply monitors the reflection of a focused laser beam from a polished fibre end face.
Abstract: A new method for measuring the refractive index profile of optical glass fibres is described. This simply monitors the reflection of a focused laser beam from a polished fibre end face. Detailed tests on the accuracy and resolution of the method are described and the index profiles of several fibres are given as an example of its feasibility.
55 citations
Patent•
12 Sep 1975TL;DR: In this paper, a multimode optical fiber waveguide with graded refractive index for lessening modal dispersion with the gradient produced at least in part by radially decreasing boron oxide content outwardly from the core center within a high silica glass core was proposed.
Abstract: A multimode optical fiber waveguide with graded refractive index for lessening modal dispersion with the gradient produced at least in part by radially decreasing boron oxide content outwardly from the core center within a high silica glass core minimizes modal dispersion by use of a non-parabolic grading function. The optimum gradient for a simple binary borosilicate system for a wavelength of from approximately 0.5 to 1.1 micrometers corresponds with α = 1.77 ± 10 percent in the equation n = n 1 [1-2Δ(r/a).sup.α] 1/2 , in which n 1 is the axial core index r is the distance from the fiber axis, a is the core radius, Δ is the relative index difference between core center and cladding and α is a power law exponent which characterizes the profile.
42 citations
TL;DR: In this article, a method to determine the refractive index and the thickness of thin films using them as leaky waveguides was proposed, where the propagation constants of two leaky modes of this waveguide were measured by means of synchronous angles.
40 citations
TL;DR: In this article, a low-loss graded-index optical fiber fabricated by a chemical vapor deposition technique was used to measure pulse dispersion, refractive-index profile, and loss measurements.
Abstract: Pulse dispersion, refractive−index profile, and loss measurements were made on a low−loss graded−index optical fiber fabricated by a chemical vapor deposition technique. The transmission loss spectra had a minimum value of 3.8 dB/km at 1.06−μm wavelength. The core refractive index had a power−law profile with an exponential coefficient of 2.2±0.1. Mode−mixing effects and the near−parabolic−index profile in a 5.6−km extrapolated fiber length (actual length =1.12 km) reduces modal dispersion by a factor of 17 from the result expected for an ungraded step−index fiber.
32 citations
TL;DR: In this article, an electronically scanned interference microscope has been used to measure the refractive index profile and its dispersion in optical fibres from these measurements, they find that the power-law profile that best equalises modal delays in GeO2-S1O2 fibres should have an exponent that varies between 19 and 25 in the wavelength range from 05 to 11 µm and is close to 2 at 09 µm.
Abstract: An electronically scanned interference microscope has been used to measure the refractive-index profile and its dispersion in optical fibres From these measurements, we find that the power-law profile that best equalises modal delays in GeO2-S1O2 fibres should have an exponent that varies between 19 and 25 in the wavelength range from 05 to 11 µm and is close to 2 at 09 µm
26 citations
TL;DR: This paper presents an approximate theory for determining the reflection losses in multimode fibers that terminate in end surfaces that are not strictly perpendicular to the fiber axis and is applicable to tilts and covers step index as well as parabolic index fibers.
Abstract: This paper presents an approximate theory for determining the reflection losses in multimode fibers that terminate in end surfaces that are not strictly perpendicular to the fiber axis. This theory is also applicable to tilts and covers step index as well as parabolic index fibers. The cross section of the step index fiber is assumed to have square geometry. This assumption simplifies the theory and is not expected to influence the obtained results.
22 citations
TL;DR: The refractive index of a small sphere and rod was measured by a method using the theory of rainbow that the minimum deviation angle of a single internally reflected ray from a sphere depends solely on the relative refractive Index of the sample to the medium.
Abstract: The refractive index of a small sphere and rod was measured by a method using the theory of rainbow that the minimum deviation angle of a single internally reflected ray from a sphere depends solely on the relative refractive index of the sample to the medium. Experimental results confirmed an accuracy of about 1%. This method is particularly suited to materials of high refractive index, because the conventional immersion method needs liquid of higher refractive index, which inevitably contains such poisonous elements as As.
14 citations
TL;DR: In this article, a new method was used in the determination of the refractive index of the active medium of a photodissociation laser at its emission wavelength and at the wavelength of a helium-neon laser.
Abstract: A new method was used in the determination of the refractive index of the active medium of a photodissociation laser at its emission wavelength and at the wavelength of a helium-neon laser. It was found that the refractive index increased with time and with the pressure of the active medium C3F7I. The measurement method could be employed in a study of the homogeneity of the active media of lasers at their emission wavelengths.
12 citations
TL;DR: In this paper, a simple formula was derived by means of a perturbation approach, yielding the cutoff values in an optical fiber with parabolic index profile in the core, and uniform cladding.
Abstract: A simple formula has been derived by means of a perturbation approach, yielding the cutoff ?-values in an optical fibre with parabolic index profile in the core, and uniform cladding. The corresponding count of propagating modes matches well with the law ?1/4, predicted by previous theories.
Patent•
24 Jul 1975
TL;DR: In this article, the authors established a given connection with distance from the center of a fiber to the maximum refractive index section of an O ring, the thickness of the O ring section and the refractive indices distribution of the ring section, an optical transmission fiber of which signal distortion is few.
Abstract: PURPOSE:By establishing a given connection with distance from the center of a fiber to the maximum refractive index section of an O ring, the thickness of the O ring section and the refractive index distribution of the ring section, an optical transmission fiber of which signal distortion is few shall be obtained.
TL;DR: A submitted manuscript is the author's version of the article upon submission and before peer-review as discussed by the authors, and the final published version features the final layout of the paper including the volume, issue and page numbers.
Abstract: • A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.
TL;DR: Time dependent boundary conditions are shown to result in considerably improved profiles, and optimum choices of diffusion parameters are chosen from minimum error in approximating focusing refractive index profiles.
Abstract: Refractive index profiles resulting from simple diffusion processes in glass are calculated, and optimum choices of diffusion parameters are chosen from minimum error in approximating focusing refractive index profiles. Time dependent boundary conditions are shown to result in considerably improved profiles.