|
 |
 |
What is “fiber optics?
 Fiber-optic lines are strands of optically pure glass as thin as a human hair, which carries digital information over long distances.
Fiber optics is sending signals down hair-thin strands of glass or plastic fiber. The light is guided down the center of the fiber called the “core”. The “core” is surrounded by an optical material called the cladding that traps the light in the “core” using the optical technique called “total internal reflection”. The “core” and cladding are usually made of ultra-pure glass, although some fibers are all plastic or glass core and plastic cladding. The fiber is coated with a protective buffer coating that protects it from moisture and other damage.
How Does an Optical Fiber Transmit Light?
 Suppose you want to shine a flashlight beam down a long, straight hallway. Just point the beam straight down the hallway -- light travels in straight lines, so it is no problem. What if the hallway has a bend in it? You could place a mirror at the bend to reflect the light beam around the corner. What if the hallway is very winding with multiple bends? You might line the walls with mirrors and angle the beam so that it bounces from side-to-side all along the hallway. This is exactly what happens in an optical fiber.
The light in a fiber-optic cable travels through the core (hallway) by constantly bouncing from the cladding (mirror-lined walls), a principle called total internal reflection. Because the cladding does not absorb any light from the core, the light wave can travel great distances.
to impurities in the glass. The extent that the signal degrades depends on the purity of the glass and the wavelength of the transmitted light (for example, 850 nm = 60 to 75 percent/km; 1,300 nm = 50 to 60 percent/km; 1,550 nm is greater than 50 percent/km). Some premium optical fibers show much less signal degradation -- less than 10 percent/km at 1,550 nm.
The light in a fiber-optic cable travels through the core (hallway) by constantly bouncing from the cladding (mirror-lined walls), a principle called total internal reflection. Because the cladding does not absorb any light from the core, the light wave can travel great distances.
Advantages of Fiber Optics
Why are fiber-optic systems revolutionizing telecommunications? Compared to conventional metal wire (copper wire), optical fibers are:
- Less expensive - Several miles of optical cable can be made cheaper than equivalent lengths of copper wire. This saves your provider (cable TV, Internet) and you money.
- Thinner - Optical fibers can be drawn to smaller diameters than copper wire.
- Higher carrying capacity - Because optical fibers are thinner than copper wires, more fibers can be bundled into a given-diameter cable than copper wires. This allows more phone lines to go over the same cable or more channels to come through the cable into your cable TV box.
- Less signal degradation - The loss of signal in optical fiber is less than in copper wire.
- Light signals - Unlike electrical signals in copper wires, light signals from one fiber do not interfere with those of other fibers in the same cable. This means clearer phone conversations or TV reception
- Low power - Because signals in optical fibers degrade less, lower-power transmitters can be used instead of the high-voltage electrical transmitters needed for copper wires. Again, this saves your provider and you money.
- Digital signals - Optical fibers are ideally suited for carrying digital information, which is especially useful in computer networks.
- Non-flammable - Because no electricity is passed through optical fibers, there is no fire hazard.
- Lightweight - An optical cable weighs less than a comparable copper wire cable. Fiber-optic cables take up less space in the ground.
- Flexible - Because fiber optics are so flexible and can transmit and receive light, they are used in many flexible digital cameras for the following purposes:
- Medical imaging - in bronchoscopes, endoscopes, laparoscopes
- Mechanical imaging - inspecting mechanical welds in pipes and engines (in airplanes, rockets, space shuttles, cars)
- Plumbing - to inspect sewer lines
- Attuned with existing CCTV Systems
- Archive backup to CD or DVD
Because of these advantages, you see fiber optics in many industries, most notably telecommunications and computer networks
|
|
|
|
|
|
