Concentration effect on optical amplification characteristics ofEr-doped silica single-mode fibers

Optical amplification characteristics for Er-doped silica core single-mode fiber amplifiers with different Er concentrations pumped by 1.48-μm-wavelength laser diodes are studied. Optical gain drastically depends on Er concentration, even when the Er concentration is less than 1000 p.p.m. In the case of the 40-mW incident pump power, the maximum net gain for the fiber containing 77 p.p.m. Er is higher than that for the fiber containing 970 p.p.m. Er by 11.4 dB