POLARIZATION COUPLING AND TRANSVERSE INTERACTION OF SPATIAL OPTICAL SOLITONS IN A SLAB WAVE-GUIDE

The interaction of two initially parallel spatial optical solitons is analyzed numerically, with consideration of the nonlinear polarization coupling in a planar slab waveguide. The phase difference of the soliton pair associated with the TE and the TM fundamental modes is either 0 or pi, and the orthogonal polarization is excited by a weak field of the same or an apposite transverse symmetry. Polarization coupling is shown to occur if the transverse spatial symmetries in both modes are different, although the linear birefringence is completely neglected. With this effect the nonlinear polarization instability in a weakly birefringent waveguide can be influenced by the choice of the initial transverse symmetries. The application of this interaction between even and odd fields for modulation or switching is discussed. The influence of the initial polarization errors of the strong field is shown to be reducible if the strong field and the modulating weak field have opposite transverse symmetries.