Fiber-optic communication

Fiber-optic communication transmits information as modulated light through optical fibers. It carries data over distances from a few meters to transoceanic spans with low signal loss.

Optical fiber: A flexible strand of glass or plastic that guides light along its length. Its core and cladding confine the light that carries the signal.
Refractive index: A measure of how much light slows and bends in a material. The index difference between fiber core and cladding helps guide light.
Submarine communications cable: A cable laid on the seabed that carries telecommunications signals between land stations. Optical fibers in these cables carry most intercontinental internet traffic.
Copper cable: An electrical cable that carries signals through conductive metal wires. It offers a familiar alternative, but fiber avoids electrical interference and often supports longer, faster links.
Claude Chappe: A French engineer who developed the semaphore telegraph network in the late eighteenth century. His optical telegraph was an earlier system for transmitting information with visible signals.
Total internal reflection: The complete reflection of light at a boundary when it strikes from a higher-index medium beyond the critical angle. It is the basic ray-optics account of light confinement in fiber.
Single-mode optical fiber: An optical fiber designed to carry light in one spatial propagation mode. It limits modal spreading and supports high-capacity transmission over long distances.
Fiber to the premises: A broadband architecture that extends optical fiber to homes or businesses. It brings high-capacity optical links close to end users.
Radio communication: The transmission of information using radio waves through space or other media. It carries data wirelessly, while fiber confines optical signals to a physical path.
Daniel Colladon: A Swiss physicist who demonstrated light guiding in a curved stream of water in 1841. His experiment showed that light could follow a bent path through a medium.

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