Wave-vector space picture for radiationless focusing and beaming.

Radiationless interference of an electromagnetic wave occurs in the near field when the feature sizes of the waves are at the deep subwavelength scale. We present the propagation in such a regime using a wave-vector space picture. Using this picture, we reproduce the condition to achieve near-field focusing. We also design the initial field distribution needed for near-field beaming, where an intensity distribution maintains its shape as it propagates. We conclude the discussion by proposing a possible implementation of the near-field beaming scheme.