Step index and graded index fiber pdf merge

The valuescharts in this document are for polymer coated fibers only. Approximated analytic solutions for wave propagation in gradedindex optical fiber have been found in the case of a. Many fiber parameters can be expressed in terms of v, such as. It compares both step index and graded index fibers. One of the possible reasons for the agreement not to be complete is that it. Thi s is because high intermdal disper sion would limit the inforrnation carrying capacity. The refractive index of the core is uniform and step or abrupt change in refractive index takes place at the interface of core and cladding in step index fibres. In the case of graded index fiber grin fiber the refractive index of the core varies parabolically from the.

Step index definition is an index cut into the fore edge of a book in the form of steps with the edge of each set of leaves preceding an indexed leaf being cut away. Fiberguides metazlied coatings increase the attenuation of the fiber. Graded index or step index multimode fiber fiber optic. Stepindex fibers have a uniform core with one index of refraction, and a uniform cladding with a smaller index of refraction. Comprehensive theory of dispersion in gradedindex optical fibers.

For example, the number of guided modes in a step index multimode fiber is given by v 2 2, and a step index fiber becomes singlemode for a given wavelength when v 4 dispersionmultimode graded index figure 2. These fibers are not standard fibers and are typically only used in specialty applications. This paper reports on some theoretical and experimental investigations of the radial refractive index gradient that maximizes the informationcarrying capacity of a multimode optical waveguide. When plotted on a graph as a function of distance from the center of the fiber, the index of refraction resembles a stepfunction. Silica core silica clad polymer or metal coated trade name. Unlike stepindex fibers, the value of the refractive index of the core n1 varies according to the radial distance r. A second mode travels at a steep angle and bounces back and forth by total internal reflection. It is used for shorter distances at very low pulse frequencies. Numerical analysis of primary rainbows from a homogeneous. Anhydrous graded index agi multimode silica core silica clad polymer or metal coated fiber. Based on above, there are three types of fiber optic cable. There are several types of single mode gradedindex fibers. What is the difference between step index and graded index. The value of n1 decreases until it approaches the value of the refractive index of the cladding n2.

A multimode gradedindex fiber has a core of radius a. However, there is a step between the cladding and the external medium. In the case of graded index fiber, the refractive index of a core is a constant and is larger than the refractive index of the cladding. Step index fiber and graded index fiber, step graded index. Osa pulse broadening in gradedindex optical fibers. With product ranges available offering polarization maintaining, bendinsensitive, rareearth doped, claddingpump and photosensitive fibers. Analysis of the use of tapered gradedindex polymer optical fibers.

The refractive index of core is nonuniform, the refractive index of core decreases parabolically from the axis of the fiber to its surface. The light propagation is mainly by meridonial rays. The large core diameter and high numerical aperture provide efficient coupling to a led source and has excellent bending loss resistance. These fibers are primarily used in data transmission applications where more. If you recall, there are two types of multimode fiber. Comprehensive theory of dispersion in gradedindex optical fibers citation for published version apa. The primary difference between this work and previous studies is that the dispersive nature of core and cladding materials is taken into consideration. Within the multimode fiber choices, the degree of refraction change between the core and the cladding varies between graded index and step index. Fiberguides agi fibers feature a graded index profile instead of a step index profile. Information on single mode gradedindex fibers can be found in the references in appendix 2.

Plexiglass, widely used as core material for gradedindex fiber 11 in. The refractive index of the core of the step index fiber is constant through out the core. Difference between step index fiber and graded index fiber. Stepindex optical fiber in stepindex optical fiber, the diameter of the core is high therefore more number of modes of propagation of light can. There are two methods to classify fiber optic cables. Rp photonics encyclopedia stepindex fibers, optical. Light is guided by a highindex circular core of uniform index, surrounded by a lowerindex cladding layer.

The cladding layer is usually covered with a plastic coating to protect the fiber from environmental hazards and abrasion. Stepindex fibers obtain their name from this abrupt change called the step change in refractive index. Reprinted with the permission of tyco electronics corporation. Step index definition of step index by merriamwebster. The most common refractive index profile for a gradedindex. Pdf the properties of modes that propagate through the step index fiber were perfectly analyzed. For a gradedindex fiber, if we draw the refractive index from the cladding region to the core. The value of n1 decreases as the distance r from the center of the fiber increases. Step index a, graded index b, and singlemode c multimode gradedindex fiber b is constructed in such a way that the refractive index between the core and cladding changes gradually. Graded index fiber is a type of fiber where the refractive index of the core is lower toward the outside of the fiber.

Graded index fiber is of only of one type that is multi mode fiber. Multimode graded index fiber graded index fiber is a type. As noted before, multimode fiber may be divided into stepindex and gradedindex fiber. Light propagation properties of graded index glass fibers.

In step index fiber, core has the constant refractive index n2 as shown in figure 7a. The parabolic graded index fibers were also analyzed. Types of optical fiber learning outcome epg pathshala. If we look at the profile drawn from the measured data of a step index fiber, it looks like a step up and step down on a staircase as shown below. Fiber alternatives in most applications, the standard multimode and stepindex single mode optical fibers mentioned before have significant performance. Comprehensive theory of dispersion in gradedindex optical.

Derive the expression of numerical aperture of step index. Pdf effects of graded order on the characteristics of the. The method yields detailed information about the spatial and angular properties of the propagating beam as well as the modal propagation constants for. The resulting pattern of reflections tends to be more uniform and dispersion is reduced. This is attributed to the difference in the material properties. This causes the light rays to bend gradually, as well. For simpler cases, the rp fiber calculator software is sufficient definition. Light paths and outputs in different fiber types, reference 5. Anhydrous graded index agi multimode fiber fiber type. For a step index fiber with a constant refractive index core, the wave equation is bessel differential equation and solutions are cylindrical functions, therefore if cladding is removed the step index fiber behaves like a cylindrical circular optical fiber with n2 1 of air. Suitable for light wave communication links and local area networks carrying voice, video and data. Modes in gradedindex multimode fiber in presence of.

The refractive index of core is nonuniform, the refractive index of core decreases parabolically from the axis of the fibre to its surface. The stepindex profile corresponds to a powerlaw index profile with the profile parameter approaching infinity. Air serves as the cladding in the simple glass tube example. In fiber optics, a graded index is an optical fiber whose core has a refractive index that decreases with increasing radial distance from the optical axis of the fiber because parts of the core closer to the fiber axis have a higher refractive index than the parts near the cladding, light rays follow sinusoidal paths down the fiber. The main idea of those approximants is to combine ra. The core of a stepindex fiber has a uniform index of refraction right up to the cladding interface where the index changes in a steplike fashion.

For an optical fiber, a stepindex profile is a refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index at the corecladding interface so that the cladding is of a lower refractive index. Guide modes of stepindex and other fibers can be calculated and optimized with the rp fiber power software. One mode travels straight down the center of the core. Graded index porous optical fibers dispersion management in. The refractive index of the core is uniform and step or abrupt change in refractive index takes place at the interface of core and cladding in step index fibers. With over 30 years experience of the specialty optical fiber industry, fibercore ltd, the world leader in its field, is exclusively dedicated to the design, manufacture and commercialization of specialty fibers. Step index fiber is a fiber in which the core is of a uniform refractive index and there is a sharp decrease in the index of refraction at the cladding. Gradedindex multimode optical fibers, optimized for signal transmission at 850 and 0 nm, are available with 50125, 62. This page describes single mode step index fiber and multimode graded index fiber.