  We show that a cooperative atom response in an optical lattice to resonant
incident light can be employed for precise control and manipulation of light on
a subwavelength scale. Specific collective excitation modes of the system that
result from strong light-mediated dipole-dipole interactions can be addressed
by tailoring the spatial phase-profile of the incident light. We demonstrate
how the collective response can be used to produce optical excitations at
well-isolated sites on the lattice.
