Gain Equalization by Mitigating Self-Filtering Effect in a Chain of Cascaded EDFA's for WDM Transmissions

A simple method of alternatively using high-inversion and moderate-inversion erbium-doped fiber amplifiers (EDFA's) in an optical amplifier chain is presented to mitigate the self-filtering effect and equalize both signal power and signal-to-noise ratio (SNR) of multiple wavelength channels in wavelength-division multiplexing (WDM) transmission systems. The performance of the compensated system with alternatively used high-and moderate-inversion amplifiers is compared with the uncompensated ones where only moderate-or high-inversion amplifiers are employed. The result shows that the compensated system has a flatter gain profile, a lesser signal power spread, and SNR degradation.