Abstract

Recently, wavelength division multiplexed (WDM) optical transmission systems have become more attractive for use in multi-media networking systems. In a WDM system, Er-doped fiber amplifiers (EDFAs) are expected to play an important role as multi-wavelength amplifier repeaters. The broadening of gain bandwidth and the maintaining of gain flatness are issues which have been discussed [1–3]. The effectiveness of an aluminosilicate EDF and an automatic gain control (AGC) scheme have been reported for the requirements mentioned above [4–7]. However, there are still some vital requirements for practical EDFA repeaters as follows. The output power level of each channel should be kept in a range determined by ASE accumulation and nonlinear effects such as self-phase modulation (SPM) and four wave mixing (FWM). The noise figure must be kept low. An efficient conversion of pump power to signal power is desired, because the allowable pump power for an EDFA repeater is limited when employing the above-mentioned AGC scheme. Another requirement is a wide input power dynamic range.

© 1995 Optical Society of America