Abstract

Pumping erbium-doped fiber amplifiers (EDFAs) at 980 nm provides the best overall performance achievable. However, it is a relatively narrow band and the constraints this imposes on pump laser wavelength have been sources of continuing concern [1,2]. Recently it has been found that the restrictions are less severe than had been originally believed [3,4], and these relaxed tolerances may lower the overall cost of the EDFA as well as reduce the impact of temperature-induced wavelength drifts in the pump laser wavelength. To further elucidate this situation, we have examined the effects of pump wavelength, λ_p, on the signal output of both power and small-signal amplifiers. Experimental and theoretical investigations of the tradeoffs between gain and noise as a result of detuning the pump wavelength are presented, together with the first measurements of noise penalties for small-signal EDFAs induced by off-peak pump wavelengths. For both power and small-signal amplifiers, a decrease in gain of less than 1 dB, with an associated increase of <1 dB in noise figure, is observed when the pump is varied over a range of 30 nm centered at 979 nm.

© 1992 Optical Society of America