The soliton self-frequency shift (SSFS) in orthogonally polarised femt
osecond soliton pulses is reported for the first time. It is shown tha
t SSFS for orthogonally polarised solitons is approximately 1/3 of tha
t for parallel polarised solitons. This is attributed to the orthogona
l Raman term. The 2pi and pi dependences of the SSFS on the phase diff
erence between the two solitons are newly obtained for parallel and or
thogonal polarisations, respectively. The largest SSFS occurs in-phase
under parallel polarisation.