Ultralong Distance Soliton Transmission Using Erbium Fiber Amplifier,
AT AND T BELL LABS HOLMDEL NJ
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Long distance transmission using a chain of optical amplifiers is potentially much cheaper and faster than with conventional electronic regenerators. Erbium doped fiber amplifiers, with their low pump-power requirements, lack of pulse chirping, independence of gain on polarization, built in automatic gain control, and perfect compatibility with transmission fibers, have done much to make this all-optical approach truly practical. It can be shown, however, that the full capacity of such a system can be realized only by using solitons. Solitons can be transmitted perfectly well through a chain of low gain amplifiers and dispersion shifted fiber segments, as long as the characteristic dispersion distance, 2Pi zo, is great enough with respect to the amplifier spacing 1. For such transmission, it is necessary only to make the path-average power over each amplification period equal to the usual soliton power in lossless fiber. We have verified this point experimentally 2,3 over paths as great as 12,000 km and at pulse rates to 2.5 Gbitss by using the recirculating loop shown in Fig. 1. In all cases, broadening of the -50 ps pulse train can be explained almost entirely by a modest jitter in pulse arrival times from the GordonHaus effect 4 furthermore, at about 5000 or 6000 km, the pulse shapes look more nearly text book perfect than they do at the beginning.
- Electrical and Electronic Equipment
- Fiber Optics and Integrated Optics