  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.
