Graded index fibers

Fig. 3. Types of optical fiber (a) multimode stepped index, (b) multimode graded index, and (c) single-mode stepped index.

Techniques for fabricating low-cost optical components such as graded index lenses, microlenses, couplers, splitters, and polarizers are needed to support optical fiber technology. Traditionally, amorphous inorganic materials have been nsed, bnt there are tremendons... 

Matejec V., Kasik I., Chomat M., Ctyroky J., Berkova D., Huttel I., Modified inverted graded-index fibers for evanescent-wave chemical sensing, Proc. SPIE 3860 (1999), Boston, pp.443-451. 

M. Chomat, D. Berkova, V. Matejec, I. Kasik, G. Kuncova, The effect of hydrodynamic conditions on the detection of aqueous solutions of toluene by means of an inverted graded-index fiber, Sensors Actuators B 2003 90 151-156. 

M. D. Felt, and J. A. Fleck, Light propagation in graded-index optical fibers, Applied Optics 17, 3990-3998 (1978). 

Figure 6.102 Schematic illustration of (a) step-index, (b) graded-index, and (c) single-mode optical fibers. Reprinted, by permission, from J. F. Shackelford, Introduction to Materials Science for Engineers, 5th ed., p. 611. Copyright 2000 by Prentice-Hall, Inc.

Single-mode fibers have many advantages over multimode fibers. See Fig. 3. Compared to the 50 or 62.5 micron core diameter of typical graded-index multimode fibers, some single-mode fibers have a core diameter near... 

Palais, J.C., (1980), Fiber coupling using graded-index rod lenses , Appl. Optics., 19(12), 2011-2018. 

Both step index and graded index fibers have been prepared by this process, using Ge02 und B203 as dopant materials. Deposition efficiencies of about 45% have been obtained. The deposition rate is typically between 0.4—1.6 g/min and blanks yielding 10 km fibers have been made. 

Fig. 17. Cross section of a fluorine doped graded index fiber etched with dilute HF14. Graded core of 35 pm diameter. (Reproduced by permission of The Electrochemical Society)...

Figure 7.9 Refractive index profiles of three common types of optical glass fiber multimode step index, multimode graded index, and single mode.

Step-index and graded-index fibers differ in their (radial) refractive index profiles. 

The bandwidth of graded index fiber is much higher (> 1000 MHz km) than of step index fibers (50 - 100 MHz km). 

Single Mode Fiber (SMF) Graded Index Fiber (GIF) Careless Fiber(CF) Multimode Fiber(MMF)... 

Fig. 3. Gold nanoparticles are formed on the surface of (A) A fused MMF-CF-MMF structure and a fused SMF-GIF- CF-MMF structure, (B) Ray Tracing schematic of Structure B, which is an in-line fiber structure consisting of single mode, graded index, coreless, and multimode fibers to expand the Gaussian beam to the surface of the coreless fiber.

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