Studies on Optimization of an Erbium-Doped Fiber Amplifier Suitable for an Optical Transmission Line Containing an Amplifier Repeater

Shigeyuki SEIKAI  Shintaro SHIMOKADO  Tadashi FUKUOKA  Tatsuo TOHI  

IEICE TRANSACTIONS on Communications   Vol.E77-B   No.4   pp.454-461
Publication Date: 1994/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Fiber Amplifiers and Their Applications to Lightwave Communications)
fiber amplifier,  WDM,  intermediate optical filter,  high gain,  erbium-doped fiber length,  

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Optical amplifier structures suitable for a 622Mbit/s repeater in an optical communication system containing one in-line amplifier have been investigated. Two wavelengths of 1.533µm and 1.549µm are considered for two cases, i.e., single-channel transmission and two-channel wavelength division multiplexing transmission. The basic amplifier structure is of a two-stage type where forward pumped and backward pumped erbium-doped fibers are connected with each other through intermediate optical filters and an optical isolator. First, the effect of the intermediate optical filters was clarified in optical gain and bit error rate characteristics. Then, the erbium-doped fiber length was optimized on the basis of the allowable optical loss of the optical system which was operated at a bit error rate of 10-9. As a result, the appropriate length of the forward pumped erbium-doped fiber was found to be about 20m for both cases of single-channel and two-channel wavelength multiplexing amplifiers. With the designed amplifier used in the system, the calculated allowable optical line loss was more than 90dB for both the cases.