A new 900-kilometer fiber-optic link between Paris and Frankfurt is the first step to creating a high-speed Internet backbone with enough capacity to satisfy bandwidth demands well into the future.
The new 100-gigabit technology uses phases of light waves instead of the older off-and-on switching laser technology. The simplest method shifts a phase by 90 degrees, one-quarter of a wavelength, to distinguish a 1 from a 0. Higher data rates require quadrature phase-shift keying, which has four possible shifts, each representing a different pair of bits.
To achieve 100 gigabits, researchers used signals with two different polarizations, which are separated at the receiver, each carrying 50 gigabits. After passing through hundreds of kilometers of fiber optics, the signal must be processed by powerful electronic circuits, says Ciena's Dimple Amin.
From New Scientist
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