WALKING SOLITONS IN TYPE-II 2ND-HARMONIC GENERATION

We find the families of spatial walking solitons propagating in quadra tic nonlinear media under conditions for type II second-harmonic gener ation in the presence of Poynting vector walk-off between the interact ing beams. The analytical stability criterion for these three-paramete r vector solitons is established. We study the shape and general prope rties of the solitons and their stability on propagation. It is found that the stationary solutions are stable at moderate positive phase mi smatch. At phase matching and negative phase mismatch there are some u nstable solutions near the cutoff.