Theory of the Soliton Self Frequency Shift.

Raman effects cause a continuous downshift of the mean frequency of pulses propagating in optical fibers. For solitons in silica fibers, the effect varies roughly with the inverse fourth power of the pulse width. At 1.5microns wavelength in a fiber with 15 ps/nm/km time-of- flight dispersion, a soliton of 250 fs duration is predicted to shift by its own spectral width after about 100 m of propagation. The theory agrees well with recent measurements.