Asymmetric transmission of light in hybrid waveguide-integrated plasmonic crystals on a silicon-on-insulator platform.

We demonstrate asymmetric transmission of light in hybrid waveguide-integrated plasmonic crystals where triangular silver islands create a regular array of nanogaps which couple to an underlying silicon-on-insulator optical waveguide. Up to 60% difference is observed between light transmission in the forward and backward directions. This asymmetric transmission of light is not caused by an external magnetic field or nonlinearity, but solely a consequence of the structure geometry.