Interaction of few-optical-cycle solitons

By using the exact four-soliton solutions of the modified Korteweg-de Vries-sine Gordon equation describing the propagation of few-optical-cycle pulses in transparent media with instantaneous cubic nonlinearity, the interaction of two such initially well-separated pulses is studied. The shapes of soliton envelopes, the shifts in the location of envelope maxima, and the corresponding phase shifts are explicitly calculated.