Vortex interference for superresolved beam waists

For over forty years, attempts have been made to realize so-called superresolving pupil functions that permit smaller spot sizes than conventional resolution limits might initially suggest. This was usually achieved by manipulating the diffracted field's zero distribution and was accompanied by huge sidelobes and diminished intensity in the region of interest. By carefully manipulating the interference pattern generated by two optical vortices of different order, one can generate beams of light with dimensions that are spatially superresolved and of controllable cross-sectional shapes. The reason for this is that interfering vortices can possess a much higher density of zeros than one would expect. Recent results employing non-integer vortex beam interference can generate superresolved spots with an intensity close to the theoretical limit for the associated Strehl ratio.