Gain and noise characteristics of Co- and contradirectionally pumped EDFAs with signal upconversion losses at different pump wavelengths

A numerical study was made at 1.5 ?m of high-concentration EDFAs pumped codirectionally and contradirectionally at various wavelengths. The model included the effects of signal upconversion and pump excited state absorption losses. An experimental verification of this study was made at the pump wavelength of 514 nm. The results of the experimental and numerical study show that contradirectional pumping gives lower gain and lower noise figures above a certain pump power, which is a function of fiber length and pump wavelength. ? 1996 John Wiley & Sons, Inc.