An EDFA works by adding erbium ions to a short piece of fiber and exciting them with a small pump laser at 980 or 1480 nm. When the telecom signal (around 1550 nm) passes through, the excited erbium atoms boost its intensity without converting it to electricity. Erbium-doped fiber amplifiers (EDFAs) are the most important fiber amplifiers for long-range optical fiber communications, efficiently amplifying signals in the 1. After the first demonstration of the laser in 1960, researchers explored rare-earth–doped materials as gain media. This is enabled by utilizing a 4C-EDF with a minimal core-dependent absorption coefficient and passive devices with low. Passive optical amplifiers are now used instead of repeaters. There are several different optical amplifiers with which to passively amplify an optical signal:. Erbium Doped Fiber IsoGain – With industry-leading efficiency, this family of fibers is used in EDFA's, Lidar units, OCT, and other applications where amplification is needed. Typical power levels that can be achieved is up to.