The design of L-band EDFA for multiwavelength applications

An accurate model for the erbium-doped fibre amplifier (EDFA) has been used to study the design criteria of single-stage (SS) and double-stage (DS) L-band EDFA for multiwavelength applications. The effects of erbium-doped fibre (EDF) length, pump configuration and pump wavelength have been studied. We show that a flat gain spectrum can be achieved in the range from 1550 to 1610 nm when the EDF length, pump power and pump configuration are appropriately chosen. Special care must be taken when selecting the EDF length. Noise figure improvement of the DS amplifier is demonstrated. The lowest noise figure was predicted for a DS amplifier with both stages co-directionally pumped at 980 nm. Transmission of 32 wavelength division multiplexed (WDM) channels with input power of -13 dB m/channel and interchannel spacing of 0.8 nm over a cascade of five L-band EDFAs has been investigated. If the WDM signal was appropriately placed, the signal level deviation between the best and the worst channel at the output of the cascade was 2.2 dB, without any gain equalizing filters or signal pre-emphasis.