Ultrahigh Interference Spatial Compression of Light Inside the   Subwavelength Aperture of a Near-Field Optical Probe
  Spatial effects of interference and interaction of light modes in the subwavelength part of the near-field optical microscopy probe have been theoretically studied. It was found that the mode interference can lead to higher spatial compression of light (lambda = 500 nm in free space) within the transverse size of 25 nm inside the probe output aperture of 100 nm in diameter. The results principally demonstrate the possibility of increasing spatial resolution of the near-field optical microscopy technique. 
N.M.Arslanov, S.A.Moiseev