Perfect 4-way splitting in nano plasmonic X-junctions.

A plasmon wave is perfectly split to 4 identical waves when encountering nano intersection. This is substantially different from the dielectric waveguides case where power coupling to vertical segments is negligible. When larger multimode plasmonic junction is realized--beating and retardation come into effect. The analysis of the plasmonic coupling in this device is helpful also in understanding plasmonic assisted enhanced transmission.