Gradient-index fibers

Figure 12.8. Transmission characteristics of some commonly used optical fibers, (a) glass fiber (b) gradient-index fiber (c) plastic-clad silica fiber (d) plastic fiber. (Reproduced with permission from the Ealing Corporation.)...

Oguara Y. / Application of gradient index fiber array to copying machine. // 1981. Kogaku, 10, pp. 111-117. 

We mentioned above three types of optical fibers step index single mode, step index multimode, and gradient index multimode. The last two types can carry more light that the step index single mode fiber. Lightness is a very important feature. Among the important features for such a system are the following (Oare, 1995) ... 

FIGURE 4-1 Refractivity and core diameter ranges for three types of optic fibers, (a) Multi-mode step-index optic fiber, (b) Multi-mode gradient-index optic fiber, (c) Single model step-index optic fiber. 

Gradient-index (GRIN) polymer fibers with a quadratic distribution of the refractive index are prepared by a novel closed extrusion process. The effects of the die geometry and the length of the diffusion zone on the refractive index distribution of the polymer fibers are studied. The results show that the non-quadratic refractive index portion of the GRIN polymer fiber can be removed by a coreshell separation die design. Also, the spatial refractive index... 

Figure 12.7 shows a schematic diagram of the LC-based VGA, where two polarization beam displacers and an LC ceU are sandwiched between two identical fiber collimators with an 80 mm working distance. The light from the input fiber is collimated by the first gradient index... 

For optical fibers, improved control over the stracture of the thin films in the preform will lead to fibers with improved radial gradients of refractive index. A particnlar challenge is to achieve this sort of control in preforms created by sol-gel or related processes. 

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