The Letter reports passive, harmonic repetition rate stabilisation at
frequencies ranging from 200 MHz to 1 GHz within a passively modelocke
d erbium doped fibre ring laser generating 1.4 ps transform-limited so
liton pulses. From observations, it is postulated the likely origin of
the self-stabilisation is the long-range repulsive interaction of sol
iton pulses due to transverse acoustic wave excitation.