The introduction to EDFA(Erbium-Doped Fiber Amplifier)

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EDFA is an optical repeater device that is used to boost the intensity of optical signals being carried through a fiber optic communications system.It was invented in 1987, EDFA exhibits its gain in the C-band and L-band, where telecomputer optical fibers show its lowest loss in the entire optical telecommunication wavelength bands.

What does Erbium-Doped Fiber Amplifier (EDFA) mean?

EDFAs are used as a booster, inline, and pre-amplifier in an optical transmission line, as schematically shown in Figure 1. The booster amplifier is placed just after the transmitter to increase the optical power launched to the transmission line. The inline amplifiers are placed in the transmission line, compensating the attenuation induced by the optical fiber. The pre-amplifier is placed just before the receiver, such that sufficient optical power is launched to the receiver.

Figure 1

It is used in the telecommunications field and in various types of research fields .An EDFA is “doped” with a material called erbium. The term “doping” refers to the process of using chemical elements to facilitate results through the manipulation of electrons.

How it Works

An optical fiber is doped with the rare earth element erbium so that the glass fiber can absorb light at one frequency and emit light at another frequency. An external semiconductor laser couples light into the fiber at infrared wavelengths of either 980 or 1480 nanometers. This action excites the erbium atoms. Additional optical signals at wavelengths between 1530 and 1620 nanometers enter the fiber and stimulate the excited erbium atoms to emit photons at the same wavelength as the incoming signal. This action amplifies a weak optical signal to a higher power, effecting a boost in the signal strength.

Before the invention of EDFA, a long optical fiber transmission line required a complicated optical-to-electrical (O-E) and E-O converter for signal regeneration. The use of EDFA has eliminated the need for such O-E and E-O conversion, significantly simplifying the system. This is especially of use in a submarine optical transmission, where more than a hundred repeaters may be needed to construct one link. The TPC-5CN (Trans-Pacific Cable 5 Cable Network), started its operation in 1996, is the first submarine optical fiber network which employed EDFA.

The EDFA rate, or amplification window, is based on the optical wavelength range of amplification and is determined by the dopant ions’ spectroscopic properties, the optical fiber glass structure and the pump laser wavelength and power. As ions are sent into the optical fiber glass, energy levels broaden, which results in amplification window broadening and a light spectrum with a broad gain bandwidth of fiber optic amplifiers used for wavelength division multiplex communications. This single amplifier may be used with all optic fiber channel signals when signal wavelengths are in the amplification window. Optical isolator devices are placed on either side of the EDFA and serve as diodes, which prevent signals from traveling in more than one direction.

EDFAs are usually limited to no more than 10 spans covering a maximum distance of approximately 800 kilometers (km). Longer distances require an intermediate line repeater to retime and reshape the signal and filter accumulated noise from various light dispersion forms from bends in the optical fiber. In addition, EDFAs cannot amplify wavelengths shorter than 1525 nanometers (nm).

Fiber-MART Optical Amplifier & EDFA

Optical Amplifiers provided by Fiber-Mart are designed for all network segments (access, metro, regional and long haul) and applications (telecom, cable and enterprise). We have a series of Erbium-Doped Fiber Amplifier (EDFA) optical amplifiers, including DWDM EDFA for DWDM systems, CATV EDFA for CATV applications, SDH EDFA for SDH networks. In addition, we can also provide Raman Fiber Amplifiers, DCM EDFA with mid-stage access, and high power amplifiers such as EYDFA.

In a word , Optical Amplifier & EDFA enables the optical transmission over long distance by amplifying signals. For more information, please visit Fiber-MART.COM .pls not hesitate to contact us for any requirements :


Optical Amplifier & EDFA
Optical Amplifier & EDFA

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