Erbium-doped Waveguide Amplifier - Laser Amplifiers - Doped Fiber Amplifiers

Doped fiber amplifiers (DFAs) are optical amplifiers that use a doped optical fiber as a gain medium to amplify an optical signal. They are related to fiber lasers. The signal to be amplified and a pump laser are multiplexed into the doped fiber, and the signal is amplified through interaction with the doping ions. The most common example is the Erbium Doped Fiber Amplifier (EDFA), where the core of a silica fiber is doped with trivalent Erbium ions and can be efficiently pumped with a laser at a wavelength of 980 nm or 1,480 nm, and exhibits gain in the 1,550 nm region.

An erbium-doped waveguide amplifier (EDWA) is an optical amplifier that uses a waveguide to boost an optical signal.

Amplification is achieved by stimulated emission of photons from dopant ions in the doped fiber. The pump laser excites ions into a higher energy from where they can decay via stimulated emission of a photon at the signal wavelength back to a lower energy level. The excited ions can also decay spontaneously (spontaneous emission) or even through nonradiative processes involving interactions with phonons of the glass matrix. These last two decay mechanisms compete with stimulated emission reducing the efficiency of light amplification.

The amplification window of an optical amplifier is the range of optical wavelengths for which the amplifier yields a usable gain. The amplification window is determined by the spectroscopic properties of the dopant ions, the glass structure of the optical fiber, and the wavelength and power of the pump laser.

Although the electronic transitions of an isolated ion are very well defined, broadening of the energy levels occurs when the ions are incorporated into the glass of the optical fiber and thus the amplification window is also broadened. This broadening is both homogeneous (all ions exhibit the same broadened spectrum) and inhomogeneous (different ions in different glass locations exhibit different spectra). Homogeneous broadening arises from the interactions with phonons of the glass, while inhomogeneous broadening is caused by differences in the glass sites where different ions are hosted. Different sites expose ions to different local electric fields, which shifts the energy levels via the Stark effect. In addition, the Stark effect also removes the degeneracy of energy states having the same total angular momentum (specified by the quantum number J). Thus, for example, the trivalent Erbium ion (Er+3) has a ground state with J = 15/2, and in the presence of an electric field splits into J + 1/2 = 8 sublevels with slightly different energies. The first excited state has J = 13/2 and therefore a Stark manifold with 7 sublevels. Transitions from the J = 13/2 excited state to the J= 15/2 ground state are responsible for the gain at 1.5 ┬Ám wavelength. The gain spectrum of the EDFA has several peaks that are smeared by the above broadening mechanisms. The net result is a very broad spectrum (30 nm in silica, typically). The broad gain-bandwidth of fiber amplifiers make them particularly useful in wavelength-division multiplexed communications systems as a single amplifier can be utilized to amplify all signals being carried on a fiber and whose wavelengths fall within the gain window.

Read more about this topic:  Erbium-doped Waveguide Amplifier, Laser Amplifiers

Other articles related to "fiber, fibers":

Synthetic Fibers - Microfibers
... Microfibers in textiles refer to sub-denier fiber (such as polyester drawn to 0.5 dn) ... Denier and Detex are two measurements of fiber yield based on weight and length ... If the fiber density is known you also have a fiber diameter, otherwise it is simpler to measure diameters in micrometers ...
ANTILLAS I
... ANTILLAS I is a fiber optic submarine communications cable that extends between the Dominican Republic and Puerto Rico ... It consists of six working optical fiber pairs with each fiber pair carrying four 155 Mbit/s Basic System Modules (BSMs), with each BSM containing sixty-three Minimum Investment Units (MIUs), for a total capacity ...
Corchorus - Uses - Fiber
... The fibers from Corchorus (known as jute) are the most widely cultivated vegetable fiber after cotton ...
Buffer (optical Fiber)
... In a fiber optic cable, a buffer is one type of component used to encapsulate one or more optical fibers for the purpose of providing such functions as mechanical isolation ... A loose buffer may contain more than one fiber, and sometimes contains a lubricating gel ... consists of a polymer coating in intimate contact with the primary coating applied to the fiber during manufacture ...

Famous quotes containing the word fiber:

    I taught school in the early days of my manhood and I think I know something about mothers. There is a thread of aspiration that runs strong in them. It is the fiber that has formed the most unselfish creatures who inhabit this earth. They want three things only; for their children to be fed, to be healthy, and to make the most of themselves.
    Lyndon Baines Johnson (1908–1973)