Resonant-tunnelling-assisted crossing for subwavelength plasmonic slot   waveguides
  We theoretically investigate the properties of crossing for two perpendicular subwavelength plasmonic slot waveguides. We show that, when encountering nano intersection, the crosstalk for the direct crossing is around 25%, almost same as throughout. In terms of symmetry considerations and resonant-tunnelling effect, we design compact cavity-based structures. Our results show that the crosstalk is eliminated and the throughput reaches the unity on resonance. Simulations results are in agreement with those from the coupled-model theory. When taking into account of the material loss, due to the unchanged symmetry properties of the modes, the crosstalk is still suppressed. Our results may open a way to construct nanoscale crossings for high-density nanoplasmonic integration circuits. 
Sanshui Xiao and Niels Asger Mortensen