Reflection and Splitting of Channel-Guided Solitons in Two-dimensional Nonlinear Schr\"odinger Equation

Solitons confined in a channel are studied in the two-dimensional nonlinear Schroedinger equation. When a channel branches into two channels, a soliton is split into two solitons, if the initial kinetic energy exceeds a critical value. The branching point works as a pulse splitter. If it is below the critical value, the soliton is reflected. The critical kinetic energy for splitting is evaluated by a variational method. The variational method can be applied in the design of channel systems with reduced reflection.