  The energy sharing collision of bright optical solitons in the Manakov
system, governing pulse propagation in high birefringent fiber, is employed
theoretically to realize optical logic gates. Especially, for the first time,
we successfully construct (theoretically) the universal NOR gate and the OR
gate from the energy sharing collisions of just four bright solitons which can
be well described by the exact bright four-soliton solution of the Manakov
system. This construction procedure has the important merits like realizing the
two input gates with a minimal number of soliton collisions and possibilities
of multi-state logic. The recent experiments on Manakov solitons suggest the
possibility of implementation of this theoretical construction of such gates
and ultimately an all optical computer.
