  We experimentally demonstrate control over the direction of radiation of a
beam that passes through a square nano-aperture in a metal film. The ratio of
the aperture size and the wavelength is such that only three guided modes, each
with different spatial symmetries, can be excited. Using a spatial light
modulator, the superposition of the three modes can be altered, thus allowing
for a controlled variation of the radiation pattern that emanates from the
nano-aperture. Robust and stable steering of 9.5 degree in two orthogonal
directions was achieved.
