Refraction Light Control by Constructing Output Interface Topography of Metal Waveguide Arrays

We investigate a nanoscale metal waveguide array (MWGA) structure and demonstrate that negative refraction effect exists from the visible to infrared frequency. Our numerical analysis shows that this effect is related to output
interface of MWGAs. Refraction light would have different directions on the gradient shaped output surface as a result of phase retardation control by waveguide thickness. Finite-difference time-domain analysis shows that more sharp superdiffraction limit imaging can be obtained by constructing convex-like output interface topography.