Low-loss intersection of subwavelength plasmonic slot waveguides

The properties of crossing for two perpendicular subwavelength plasmonic slot waveguides are theoretically investigated. Results show when encountering a nano intersection the crosstalk for the direct crossing is around 25%, almost the same as throughput. In terms of symmetry considerations and resonant-tunnelling effect, we design two types of compact cavity-based structures. Our results show that the crosstalk is eliminated and the throughput reaches the unity on resonance. Simulation results are in agreement with those from coupled-mode theory. Taking material loss into account, the symmetry properties of the modes are preserved and the crosstalk remains suppressed. Our results may open a way to construct nanoscale crossings for high-density nanoplasmonic integration circuits.