Early Stages of Fiber Optic Communication

Laser is 56 years old this year, the age at which most women and men attain wisdom We are lucky to witness the developments in Laser market and its contribution to fiber optic communications. Laser has contributed heavily to the progress of human beings. Without laser it would have been almost impossible to transmit huge amount of data through optical fibers. The invention of laser in 1960 pushed for the researchers to find out a suitable medium for optical communication. It took another six more years for the inventors to demonstrate the capabilities of optical fiber to carry laser signals. In short, the invention of Laser and subsequent invention of optical fibers made today’s fiber optic communication possible.

In 1966, researchers suggested possible use of optical fibers to carry laser light and the propagation of laser light through optical fibers. Copper cables that carry communication signals in the form of electricity is in network even now. A new medium was proposed to carry laser light in a similar manner as the copper cables carry electrical signals. We can say in a broad sense, optical fibers are capable for guiding light through them in a manner similar ot the guiding of electrons in copper wires.

Researchers demonstrated the light guiding in optical fibers. First developed optical fibers had attenuation in the range of 1000 dB/km, but scientists were hopeful to reduce it make the optical fibers suitable for telecommunication. A major invention in the history of optical fibers happened when some researchers could reduce the attenuation to 20 dB/km at wavelength of 1000 n m. That was in 1970. Also researchers demonstrated the ability of GaAs (Gallium Arsenide) semiconductors to operate continuously at room temperature. Gallium Arsenide, Indium Phosphate, Gallium Antimonide and Gallium Nitride are semiconductor materials used in junction diodes to emit light.

The researches and developments in optical fiber manufacturing technology and light sources propelled the efforts for developing fully optical fiber based communication systems. The quest for more effective medium for transmission of communications signals is going on. It was almost 40 years before that the real progresses in optical communications had started. Though we can’t mark time periods for each phase of developments, the following could be justified to common reason. The progresses in optical communication have been driven by the bandwidth demand. As Moores law states the bandwidth demand doubles every 18 months. The demand for bandwidth marked the saturation of existing technology after a certain phase. For academic purpose we can describe those phases as below;

First optical fibers introduced were operated at 850 nm wavelength. For injection of light pulses, Gallium Arsenide semiconductor lasers were used. Commercial availability of such systems started in 1980s. Those transmission systems were able to operate at a few megabits per seconds which may seem negligible to consider as speed of optical communications systems from the current perspectives.The transmission speed was at around around 45 Mbps. A significant achievement was in the transmission span. A single span was up to 10 kilometers, which was ten times higher than the maximum span allowed by a coaxial system during 1980s. The advantage offered by optical transmission systems in reducing the number of joints by extending the span, thrilled system designers. The total project cost reduced drastically when optical transmission systems were employed.

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Author: Fiber

Chief Editor of Fiber Optic Mania Magazine

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