PASSIVE EQUALIZATION OF NONUNIFORM EDFA GAIN BY OPTICAL FILTERING FORMEGAMETER TRANSMISSION OF 20-WDM CHANNELS THROUGH A CASCADE OF EDFAS

Through the incorporation of optical filters in a cascade of Erbium-do ped fiber amplifiers (EDFA's), with each amplifier exhibiting nonunifo rm gain, we determine the optimal conditions for passively equalizing many wavelength division multiplexed (WDM) channels while maintaining a high SNR. For 20 WDM channels spaced 0.5 nm apart, it is found that 3-dB, 2-nm-wide notch filters with center wavelength at 1.560 mum will provide sufficient SNR equalization for potential megameter transmiss ion when located after every 20 EDFA's. This performance is achieved w ith no a priori knowledge of the input or output signals.