Transmission and reflection characteristics of metal-coated optical   fiber tip pairs
  The optical transmission and reflection in between two metalized optical fiber tips is studied in the optical near-field and far-field domains. Besides aluminum-coated tips for near-field scanning optical microscopy (NSOM), specifically developed gold-coated fiber tips cut by focused ion beam (FIB) are investigated. Transverse transmission maps of sub-wavelength width clearly evidence optical near-field coupling between the tips for short tip distances and becomes essentially Gaussian-shaped for larger distances in the far-field regime. Moreover concentric reflection fringes observed for NSOM-type tips illustrate the influence of the receiving fiber tip on the emission pattern of the source tip. 
Jean-Baptiste Decombe, Jean-Fran\c{c}ois Bryche, Jean-Fran\c{c}ois   Motte, Jo\"el Chevrier, Serge Huant, and Jochen Fick
physics.optics