Features and Principle of Operation of Fiber Lasers based on Active Fiber Doped with Rare-Earth Ions

A review of the results of studies of fiber lasers, as well as methods for improving the spectral characteristics of fiber-optic communication systems, has been carried out. The principles of operation of fiber lasers and optical transitions between meltiplets of the ground and excited states of rare-earth elements are considered. It is shown that each radiative transition corresponds to a certain wavelength, as well as the wavelength of the radiation of which depends on the type of rare-earth ions doped with impurities.