(CT) Going Optical Lesson
Going Optical Lesson
Introduction
Optical communications were developed as the most economical and highest quality means to carry digital signals and the emerging features through the communications network. These systems not only have extremely higher capabilities for data rates, bandwidth, than physical cable or microwave radios, but they can effectively be used over very long distances. For example, communications from North American to parts of Europe was only available through the limited channels of satellite or submarine copper cables installed across the ocean floor. The first Trans-Atlantic submarine optical cable was initialized in 1988. Since then, all continents but Antarctica are connected through optical fibers.
Explore
Fiber Optics is the use of optical fiber (glass or plastic) and optoelectronic equipment to transmit and receive light signals used for communications, and other specific purposes. Optical fibers used in communications systems are pure glass fibers, about the width of a human hair, created through a specialized manufacturing process. Options exist for optical plastic cables, but glass is more often used for communications because it has greater reach without need for amplification. In other words, optical fibers have lower signal loss over distance than other cable technologies and thus can go further without signal regeneration. The fibers are flexible enough to be bundled with other fibers strands and embedded in cables for handling in a similar fashion as copper cables. These optical fibers are used to carry communication signals through transmission of pulses of light. This on/off pulsing is well suited for digital communications.
Fiber optics was initially used for long distance communications, but now fiber optic communications systems are used for local transmission within a community, connection to a home or structure from the distribution cable on the street, communications cables within a multistory building or office park, and data networks.
Transmitters and Receivers
Watch the following video, LED and Transmitter Characteristics, to see the basics and operation of electrical to optical signal conversion in a fiber optic communications system.
On the other end of the circuit is the optical receiver. The receiver must take the optical energy, photons or light emissions, and convert the optical energy to an electrical signal. This is done in a photo detector through a process called optical absorption. Optical absorption is the conversion of the light energy into an electrical signal.
Challenge
Take Away
So what is the composition of a fiber optic cable?
The image diagrams the construction of fiber strands. The core is the part of the cable which is the “light guide” or the path where the laser beam or LED light will be focused. The cladding acts to reflect the light and carry it forward.
The image shown, Cross-section of a Fiber Optic Submarine Cable, shows the composition of submarine fiber optic cable. The glass fibers are in the center (#8) while the remaining components are layered around the glass to provide protection for the cable. See the list below for a description of the other parts.
Labeled parts of submarine cable:
1. Polyethylene
2. “Mylar” tape
3. Stranded steel wires
4. Aluminum water barrier
5. Polycarbonate
6. Copper or Aluminum tubing
7. Petroleum Jelly
8. Optical fibers
IMAGES CREATED BY GAVS