Erbium-doped fiber amplifiers and the next generation of lightwave systems

Erbium-doped fiber amplifiers (EDFAs) promise to revolutionize lightwave technology, lowering system costs while enhancing network performance and reliability. The high gain (G > 40 decibels), high output power (P > 100 milliwatts), and near-ideal noise performance achieved by EDFAs, which operate in the 1550-nanometer telecommunications window, have been unparalleled by any competing amplifier technology. EDFAs are inherently fiber compatible, insensitive to polarization effects, and immune to crosstalk among wavelength-multiplexed channels. These remarkable attributes, and the ease with which they can be realized, have propelled EDFAs from their discovery in the research laboratory to commercial availability in less than three years. EDFAs may be used as power amplifiers to boost transmitter power, optical repeaters to amplify weak signals, and optical preamplifiers to increase receiver sensitivity. The success of EDFA system experiments and the decision to use EDFAs as repeaters in the next generation of transoceanic submarine lightwave systems demonstrate the practical benefits of EDFAs and their potential in future lightwave systems.