graded-index fiber

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graded-index fiber

A multimode optical fiber in which the refractive index of the core declines from its highest value at the center of the core to a value at the edge of the core that equals the refractive index of the cladding. This design compensates for modal dispersion by allowing light rays in the outer zones of the core to travel faster than those in the center of core. It is typically used for transmitting distances of a couple of kilometers. Standard graded-index fibers typically have a core diameter of 50 or 62.5 µm and a cladding diameter of 125 µm. See step-index fiber and dispersion-shifted fiber.
References in periodicals archive ?
This pattern creates a continuously graded refractive index profile from air to the material's surface, which essentially provides a pathway for light rays to enter the material and prevents them from reflecting back out.
industry to come up with a practical cloaking device coating that uses graded refractive index nanocomposite materials to reduce an object's electromagnetic signature, making it appear flat.
Graded refractive index is of interest for both transformation optics including hyperlenses [17] and invisibility cloaks [18].
Instead of shaping the lens to aid eyesight, Isabelle Calderara, a chemist at the contact lens maker Essilor in Creteil, and her colleagues have made a lens that focuses light with a graded refractive index. In other words, the lens' power to bend light rays changes from the center to the edge, a technique that can potentially be used to make more practical corrective lenses for far-sightedness.
Recently, several continuous design methodologies and implementation by using nanoporous materials have been published on high-performance broadband graded refractive index AR coatings [2-5].
Significant research has focused on finding graded refractive index profiles which minimize reflection for a given AR coating thickness.
In order to answer the above-mentioned question, a systematic study on design of graded refractive index profile for broadband omnidirectional antireflection coatings is performed in this paper.
Using the concepts borrowed from biology, namely, selection, recombination and mutation, optimal graded refractive index profile can be obtained.
Therefore, in this paper, genetic programming algorithm is employed to design and optimize the graded refractive index profile for broadband omnidirectional antireflection coatings in order to decrease the average reflectance of AR coatings to the greatest extent.
The combination of step and graded refractive index profiles, such as in Figure 1(d), is considered in [12] for the design of dispersion compensating fibers.