Sunday, March 30, 2014

Optical Fiber Amplifiers



However, this is an inconvenient and expensive process and so it is replaced by the new optical fiber amplifier technology.

An optical fiber amplifier is an all-optical device . It is not to convert the incoming optical signal to electronic signal . Basically, you can call it an in-line laser . And an optical fiber amplifier simultaneously amplify dozens of optical channels , since they do not need to convert into electronic signals for each channel separately.

What are optical fiber amplifiers , and how do they work?

An optical fiber amplifier is a portion of an optical fiber doped with a rare earth element such as erbium or praseodymium .

The atoms of erbium or praseodymium , by high-power light ( pump laser ) are pumped into the excited state. But they are not stable in the excited state . If the optical signals are amplified by, even though the fiber , they stimulate the excited erbium atoms. The erbium atoms are excited by the high level of performance state to low power levels to jump stable state and release energy in the form of photons emitted light at the same time . The emitted photon has the same phase and wavelength of the optical input signal, thereby to amplify the optical signal.

This is a very convenient form of the amplifier for an optical fiber communication system , because an in-line amplifier , thus eliminating the need to do the optical-electrical and electrical-optical conversion process.

The pump laser wavelength and the relevant optical signal wavelengths are important parameters for the operation of fiber amplifiers . These wavelengths depend on the type of the rare - earth element is doped in the fiber , and also on the composition of the glass in the fiber.

Another important concept in the understanding of fiber amplifiers is the "profit" . Measuring the increase in gain per unit length of the fiber. Gain depends on both the materials and the operating conditions , and it varies with the wavelength for all materials.

For low input power , the output power is proportional to the reinforcement times the length of the fiber. Thus , P ( outlet) = P ( input) x gain x length

For high input powers , the gain saturation effect comes into play. To increase the input power produces less and less power , which essentially means , the amplifier of the power it needs to run to generate more power.

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