Stability of solitons in birefringent optical fibers. I: equal propagation amplitudes.

The effect of birefringence on soliton propagation in single-mode optical fibers is considered. Emphasis is on solitons with multipicosecond widths that are appropriate for communications applications. It is shown that while linear birefringence will lead to a substantial splitting of the two polarizations over 20 km, this effect can be eliminated by use of the Kerr nonlinearity. Above a certain amplitude threshold, the central frequency of each polarization shifts just enough to lock the two polarizations together.