Unit 9 Assignment
Transmitters
The purpose of this paper is to provide a comparative study and discussion of LED and laser transmitters. To begin, the definition of the terms LED and transmitter must be given.
What is a transmitter? – This device converts and electrical signal into light energy. The light energy is sent through the optical fiber. These signals have multiple sources from the human voice, to computers, to data from an industrial sensor.
What is LED? – Light emitting diodes are semiconductor light source technology. What is a laser? – This is the acronym that stands for light amplification by stimulated emission of radiation. This is also a semiconductor light source like LED. The components that make up the LED are quite different from those of Laser transmitters. LED wavelengths depend on materials that are used to make up the semiconductor, like Aluminum, gallium and arsenic. The Laser wavelength is dependent on Indium, gallium, arsenic, phosphorus. The spectral width is an important factor in determining the wavelength between LED and laser transmitters. LED spectral width is much wider than laser spectral width. Laser transmitters are considered to function at the highest level of performance, because a laser transmitter’s spectral width is much narrower than that of LED transmitters. Another comparative factor of laser and LED transmitters is the power output. The power output of a laser transmitter far exceeds LED by about 20dB. This distinction allows lasers to transmit signal further than LED transmitters. The LED transmitters are designed to support multimode optical fibers with cores sizes ranging from as little as 50um to as large as 1mm. LED transmitters are directly modulated. While laser transmitters are designed to support either single-mode optical fiber systems or multimode optical fiber systems.