Abstract

It has been recently pointed out that pseudorandom sequences of solitons can be generated and transmitted at GHz rates by direct modulation of laser diodes (LD) when biasing slightly below threshold¹. Using this bias current the response of the gain-switched laser to a bit ”1” is independent of the previous input bits². Then the large pulse fluctuations due to pattern effects, produced by the random sequences of input bits, are avoided and soliton generation under pseudorandom word modulation conditions is possible. Using solitons generated by gain-switched LD at GHz rates a large time jitter has been observed after transmission over transoceanic distances³. We have shown that this is due to the pulse-to-pulse frequency jitter originated in the LD⁴. Other important effects at high bit rates are soliton interation and Gordon-Hauss jitter. It has been demonstrated that midsystem optical phase conjugation (OPC) can reduce these effects in periodically amplified soliton transmission systems⁵.

© 1995 Optical Society of America