In contrast to copper wire – which transmits electrical signals through the cable – fiber optic transmits signals in the form of light from point A to point B. As we’ve learned in fiber optic technician training, a fiber optic communication network is made up of transmitting and receiving circuitry, which is composed of a light source and detector devices.
With the help of a light source and transmitter circuitry, electrical signals are converted into light signals. The light beamed from the light source is transported by a fiber optic cable to the circuitry. From there, the info is beamed back to the electrical signal via a receiver circuit.
The receiver circuit is made of a light detector that comes with an appropriate electronic circuit, which measures the frequency, phase, and magnitude of the optic field. In this set up, laser and LED may be utilized as light sources based on what it will be used for.
The 3 Basic Components of a Fiber Optic Based Communications System:
The Source of Light
Your light source will depend on what you will use it for, whether for LAN or for long distance communication systems. The factors to be considered are speed, spectral line width, power, temperature, cost, and others. At the moment, there are two commonly used light sources: Laser and LEDs.
For short distances or low data applications, light emitting diodes (or LEDS) are used because of their low bandwidth and power capabilities. Two popular LED formats are edge emitting and surface systems. Design-wise, surface emitting diodes are simple and can be relied on; but, due to its bigger line width and higher limitations of modulation frequency, edge-emitting diode are more frequently used.
Laser Diodes are used for greater distances and high data rate transfer due to its capability to transmit high power and high speed despite of having a narrower spectral line width.
Today, many improvements and developments have made these sources more convenient to use. These two light sources are controlled using either external or direct modulation processes.
Fiber Optic Cable
Optical fiber is a type of cable, which is also identified as a cylinder-shaped dielectric waveguide consisting of low-loss material. An optical fiber functions based on the parameters, such as the location wherein it is being used, how strong it is against bending, how durable, or how rigid it is. A fiber optic cable is made using high quality glass or plastic; and it is highly flexible. The size of the fiber optic cable is slightly thicker than a piece of human hair.
Photo or Light Detectors
The purpose of light detectors is to change the light signal back to an electric signal. Optical receivers used in optical communications commonly use two types of photo detectors: avalanche photo diode and PN photo diode. The material composition required for these devices vary depending on the application’s wavelengths. The most commonly used materials are germanium, InGaAs, or silicone.
