What is fiber optics and how does it work?

WHAT IS FIBER OPTICS?

Fiber optics is a method of data transmission that consists of sending encoded information through a beam of light projected through a glass tube or pipe. It has its origins in the work of 19th-century scientists Jean-Daniel Colladon (a Swiss physicist who discovered that a continuous ray of light could shine through a water pipe through internal reflection) and John Tyndall (a physicist Irishman who formally demonstrated internal reflection to the Royal Society in London by illuminating the stream from a jug of water.)

AND HOW DO FIBER OPTIC CABLES WORK?

Fiber optic cables are made of very thin strands of glass or plastic, each of which is less than a tenth the thickness of a human hair. These threads are known as optical fibers, and each of them is capable of transmitting around 25,000 phone calls. Fiber optic cables typically range from a minimum of two to several hundred strands optical works corporation.

To ensure uninterrupted light transmission, the glass used in the manufacture of optical fibers must be very pure, so the core of a cable is usually made of silicon dioxide. Surrounding this core is a somewhat different layer or coating of glass, which is usually infused or "doped" with remnants of elements such as boron or germanium.

The core and cladding are covered with a plastic cladding and a Kevlar or metal fiber cladding, and the entire assembly is sealed against water and dirt by a protective outer layer.

A complete cable can only be a few centimeters in diameter, with a core of only five to ten millionths of a meter.

LIGHT BOUNCING AROUND

Transmission through fiber optics is achieved when the photons or light particles that form a beam hit the glass walls of a fiber optic at a very shallow angle (forty degrees or less), and are reflected back as if hitting a mirror. This is known as total internal reflection, and ensures that all transmitted light remains within the tube.

The physical structure of the cable contributes to this, since the doping applied to the coating reduces its refractive index with respect to that of the core (different reflection characteristics) and effectively limits the light beam to the core of the fiber.

Continuous lengths of cable up to 100 km (60 miles) are possible, with light bouncing off the walls and reflected in the mainstream at speeds of about two-thirds of the natural speed of light when empty (which is about 300,000 km or 186,000 miles per second).

That is why there is normally an equipment booth located 80 to 100 km (40 to 60 miles) away on long distance transmission lines, to augment or retransmit signals along the next section of cable.