Optimum Design for Efficient Erbium-Doped Fiber Amplifiers.

The gain and pumping efficiency of erbium-doped fiber amplifiers is analyzed as a function of guiding parameters and Er-doping profile for two pump wavelengths of lambda sub p = 980 nm and lambda sub p = 1.47microns. Three designs of fiber-amplifier waveguide are considered: (a) one with the same mode size as standard 1.5microns communication fibers (Type 1); (b) one with the same mode size as standard 1.5microns dispersion-shifted fibers (Type 2); and (c) one with mode size smaller than those of communication fibers (Type 3). For a 1.47microns pump, fundamental LP sub (01) mode excitation is assumed, while for lambda sub p = 980 nm-pump, concurrent excitation of LP sub (11) modes is considered.