Enormous Bandwidth

For glass fibers, there are two "optical windows" where the fiber is most transparent and efficient. The centers of these windows are 1300 nm and 1550 nm, providing approximately 18,000 GHz and 12,000 GHz respectively, for a total of 30,000 GHz. This enormous bandwidth is potentially usable in one fiber. The only limitation is the electronic circuits that modulate the light waves to represent the data. Electronic ciruits have yet to come close to the frequencies of light.Plastic is also used for short-distance fiber runs, and their transparent windows are typically 650 nm and in the 750-900 nm range.