Raman effects on solitons near the zero group dispersion point.

Summary form only given. Recently, the authors proposed the use of solitons at the zero group dispersion point of a single-mode optical fiber for long-haul communication, a scheme that combines the low-power requirement of propagation at the zero group dispersion point with the robustness of the soliton approach. To implement this scheme successfully issues such as the Raman self-frequency shift and the Raman amplification have to be clarified. The Raman self-frequency shift affects solitons by shifting the carrier wavelength away from the zero group dispersion point. Assuming a delayed nonlinear response, the Raman effect is proportional to the intensity of the pulse, and the lower power of solitons at the zero group dispersion point results in a much smaller frequency shift. Preliminary numerical results show that there is a negligible effect on a soliton of 1-ps pulse width after propagating a distance of 36 km. Raman amplification, which is an essential element in an all-optical long-haul communication system, should sustain solitons against dissipation.