Abstract

A serious problem for wavelength-division multiplexing (WDM) networks is the wavelength-dependent gain saturation of the erbium-doped fiber amplifiers (EDFAs). Because of this effect, the loss or removal of one or more channels at the input of an EDFA can cause large changes in the output powers of the remaining channels. Gain clamping,¹ and channel equalization¹³ have been shown to be effective methods to stabilize the WDM output of the EDFAs. As an alternative solution, we have investigated EDFA gain control under multiwavelength operation, comparing different methods: (1) pump power control,⁴ (2) adding a co-propagating control signal,⁵ and (3) adding a counter-propagating control signal. Previously, Refs. 4 and 5 demonstrated the effectiveness of these gain control techniques for single-channel operation.

© 1996 Optical Society of America