Gain regulation of Erbium-doped fiber amplifiers

In this paper, we discuss main issues concerning light amplification in Erbium-doped fiber amplifiers. We investigate the impact of propagation delay through Erbium-fiber; influence of stochastic adding and dropping of wavelength division multiplexing on the gain of EDFAs; and, finally, we explain the amplified spontaneous emission of ions, which is an optical noise in EDFAs. Using backward ASE as an output feedback signal and applying the traveling wave model paradigm, we apply some basic ad hoc trial-and-error methods from elemental control theory to improve the gain of EDFAs in presence of ASE.