Dynamics of pulses in optically coupled active optical fibres with different parameters

The dynamics of a wave packet formed by two modes propagating in optically coupled channels with different mode gain increments is studied. It is shown that in the case of a linear intermode coupling, radiation in such structures is decomposed into two autonomous partial pulses with different values of the effective dispersion parameters determining their dynamics. The conditions of the temporal compression and realisation of the superluminal velocity of the envelope maximum for partial pulses and the wave packet as a whole are also investigated.