Dr Hess envisages a ray of light travelling down an optical fibre made from two materials: a core with a negative refractive index and an outer sheath with a positive one.

赫斯博士构想出一个画面，即一道光正穿越于一个由两种材料制作的光导纤维，一种是具有正折射指数的纤维核，另一种则是具有正折射指数的外围。

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The deceleration gives the new medium a different refractive index.

减速使新介质获得不同的折射率。

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In natural materials, light waves entering at an Angle always bend to plunge more steeply into the material-the hallmark of a refractive index greater than 1.

在自然物质中，以一定角度进入的光波，进入物质后的角度更小——标志着折射率大于1。

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Dr Feld also has plans to use beams of different colours, since each colour has a slightly different refractive index in a given material.

ECONOMIST: Microscopy

Shining an appropriate light on such a wire from the outside would alter its refractive index (a measure of how fast light travelling inside the wire can move).

ECONOMIST: New-age crystals

When light travels through glass, it slows down (the amount it slows is measured by a number called the refractive index).

ECONOMIST: A way to detect Earth-sized planets around other stars