A System view of Optical Fiber Communication. Prepared by. Ismail Ali Al-Qaram. Zeyad Al-Qabbani. Ali Kamel Al-Awami. Overview:. An optical fiber is a glass or plastic fiber designed to guide light along its length by total internal reflection.
A System view of
Optical Fiber Communication
Ismail Ali Al-Qaram
Ali Kamel Al-Awami
An optical fiber is a glass or plastic fiber designed to guide light along its length by total internal reflection
Optical fibers are widely used in fiber-optic communication, which permits digital data transmission over longer distances and at higher data rates than electronic communication.
Optical fiber was developed in 1970 by Corning Glass Works with attenuation low enough for communication purposes (about 20dB/km)
Types of optical fiber:
- large core, diameter: 100 microns
- travel in direct route, other rays zigzag as they bounce off the cladding
- pulse, spread out, losing its well-defined shape
- core has refractive index that diminishes gradually from the center axis out toward the cladding.
- the light rays move down the axis advance more slowly than those near the cladding.
- light in the core curves helically.
- shortened path & higher speed less dispersion.
BASIC CABLE DESIGN
- holds up to 12 fibers per buffer tube.
- fibers are loosely packaged in gel filled buffer tubes to repel water.
- endure outside temperatures and high moisture.
- Typically, distance not to exceed 50 feet.
- often used for intra-building
- (Temperature rating -40ºC to +85ºC).
- Typically, long distance
Communication System Using Optical Fiber
- The most commonly used optical transmitters are semiconductor devices such as Light emitting diodes (LEDs) and laser diodes.
- A semiconductor laser emits light through stimulated emission rather than spontaneous emission
high output power (~100 mW)
- efficiency (~50%)
- wide spectral width of 30-60 nm
- Output power 100 microwatts
- efficiency (~1%)
- wide spectral width of0.81-0.87 µm
- High data rates, long distances
- Solution for fiber attenuation and fiber distortion.
- amplifies the optical signal directly without having to convert the signal
into the electrical domain.
- Made by doping a length of fiber with an rare-earth mineral (erbium), and pumping it with light from a laser with a shorter wavelength than the communications signal (typically 980 nm)
- The main component of an optical receiver is a photo detector that converts light into electricity through the photoelectric effect.
- detectors are also used due to their suitability for circuit integration in regenerators and wavelength-division multiplexers
Wavelength-Division Multiplexing (WDM) :
Comparison between electrical transmission
and fiber optics
Thanks for listening