Science of the Rainbow

The spectrum depends upon light of different colours being slowed by different amounts: the refractive index of a given substance, say glass or water, is greater for blue light than for red. You could think of blue light as being a slower swimmer than red, getting tangled up in the undergrowth of atoms in glass or water because of its short wavelength. Light of all colours gets less tangled up among the sparser atoms of air, but blue still travels more slowly than red. In a vacuum, where ther...

 Overview of Optical Networks

Optical fibers can transmit digitized light signals over long distances because of the purity of glass fiber combined with improved electronics technology. With some acceptable transmission loss, low interference, and high-bandwidth potential, an optical fiber is almost an ideal transmission medium. Optical communication systems may sometimes be combined with electrical components. In such systems, electrical data bits are converted into light, using a certain wavelength; when the transmissio...