A new dispersion managed soliton transmission system where the D map
period is the same as the amplifier period and the pulse breathing the in
the +D sections of the D maps is approximately symmetrical. Pulse
breathing symmetry by one or both of two techniques. In one technique a
guiding filter is placed at the beginning of the D map period such that
the guiding filter reduces the bandwidth of soliton pulses passing
through it by a minimum amount. Consequently, pulse breathing symmetry is
restored. The path average pulse energy vs. D behavior of solitons
propagating through the D map is changed such that (1) solitons of modest
bandwidths have adequate energy at or near D=to provide for error-free
transmission over transoceanic distances at or near D=0, and (2) such
that the path average pulse energy is nearly independent of D, at or near
D=0 for solitons of various pulse widths. The transmission system having
this D map is much more tolerant of variations in D and pulse width than
the prior art. Another technique uses two different types of +D fiber in
the +D section so that there is a step change in the ratio of D divided
by the cross-sectional area of the fiber, or "A.sub.eff", as solitons
propagate from one type of +D fiber to the other type of +D fiber in the
+D section. This step change in ##EQU00001## nullifies the effects of
the variation in pulse intensity thereby restoring the pulse breathing
symmetry. Furthermore, through the use of intermediate Raman
amplification, signal loss in transmission lines having very large
amplifier periods, e.g., 80 km or 120 km, is overcome.