  In this paper, super-focusing using radiationless electromagnetic
interference is extended to the visible regime. It is shown that the
highest-order mode of a specifically designed metal-dielectric waveguide array
can provide the rapidly oscillating source field for radiationless
interference. Using finite-difference time-domain simulations, an example
structure is demonstrated. This structure provides focusing to 0.21 of the
optical wavelength at a distance of half the optical wavelength from the
source.

Optics