The ability to achieve quantum-limited amplification of optical signals contained in optical fibers is arguably among the most important technological advances that are underlying our modern information society. In optical telecommunications, the choice of 1550 nm wavelength band is motivated not only by loss minima of silica optical fibers (a development recognized with the 2008 Nobel Prize in Physics), but equally by the existence of ways to amplify these signals, crucial to achieve trans-oceanic fiber optical communication.