Abstract

While optical fiber medium offers a THz-wide bandwidth, silica-based Erbium-Doped Fiber Amplifiers (EDFA) represent a bottleneck in broadband all-optical lightwave systems. This is due to their spectral gain ripples and non-uniformities, resulting in gain and Signal-to-Noise Ratio (SNR) discrepancies between channels. Different techniques have been proposed to overcome this impediment [1-4]. However, they have never been demonstrated over a spectral range larger than 14 nm while EDFAs offer more than 20-nm operating bandwidth. Based upon a different glass material, Erbium-Doped Fluoride Fiber Amplifiers (EDFFA) exhibit gain spectra flat and more uniform than silica-based EDFAs [5,6]. In the experiment reported here, this gain flatness advantage is used over 25 nm with 16 wavelength-multiplexed channels for cascade operation in a 440 km-long system. A transmission experiment demonstrates a potential of 40-Gbit/s total capacity through 440 km standard fiber, using fluoride-based EDFAs and a 16-channel multiplex.

© 1994 Optical Society of America