  Using optical eigenmodes defined by the interaction between the
electromagnetic fields and photonic structures it is possible to determine the
optimal illumination of these structures with respect to a specific measurable
quantity. One such quantity considered here is the electric field intensity in
the hotspot regions of an array of nano-antennas. This paper presents two
possible methods, both based on optical eigenmodes, to determine the optimal
and most efficient illumination that couples to a single hotspot on top of a
single nano-antenna taken from an array of nano-antennas. The two methods are
compared in terms of cross-talk and overall coupling efficiency.
