  We propose a surface plasmon-polariton based nano-rod array lens structure
that incorporates two additional lateral input channels, with the ability to
control the focal length and the deflection of the transmitted beam through the
lens actively by the intensity of the channel sources. We demonstrate by
numerical simulations that, applying the sources with the same intensity can
change the focal point and the beam waist, whereas unequal intensities generate
an asymmetric field profile in the nano-rod array inducing an off-axis beam
deflection.
