Switching a Dirac soliton by a weak signal in binary waveguide arrays with varying propagation mismatch

We numerically study the switching of the discrete Dirac solitons in binary waveguide arrays with the increase of absolute value of the propagation mismatch parameter along the longitudinal axis. We demonstrate that the Dirac soliton will be compressed in the transverse direction during propagation and will finally be localized in just one waveguide. We show that although at the input the system is completely symmetric, at the output the symmetry can be broken if the propagation mismatch parameter and the nonlinearity coefficient have different signs. In this case, with a very weak signal initially added at the input, we can switch the Dirac soliton from one waveguide to another. Meanwhile, if they are of the same sign, then the compression process of the Dirac solitons will be very stable, and the symmetry of the Dirac soliton profile will be conserved during propagation. © 2019 Optical Society of America.