ABSTRACT
Superfluorescent fiber sources (SFS) first appeared in 1987, shortly after the advent of low-loss rare earth doped silica fibers. Similar to a laser, an SFS relies on the amplification of stimulated emission, but it differs from a laser in that it does not utilize an optical resonator. Its output is simply the superfluorescence, or amplified spontaneous emission (ASE), generated by the optically pumped laser ions of the doped fiber. Because this ASE has not been spectrally filtered by a resonator, it covers a sizable fraction of the bandwidth of the laser transition, which is generally quite broad for rare earth ions in a glass host. Thus, unlike most lasers, an SFS emits a broadband signal, typically a few to a few tens of nanometers. It is this unique property that spells its key role in several important applications.
