Spatial distribution of electromagnetic fields of sub-wavelength sized apertures

In this paper we review experimental results describing the radiation characteristics of a tapered metal coated optical fiber tips. We have measured both the far field as well as the integrated near field contribution to the radiation transmitted through a sub wavelength sized optical aperture located at the apex of the fiber tip. The tapered optical fiber tips are fabricated using two different techniques. Firstly the tips were prepared by CO/sub 2/ laser melting and pulling a monomode optical fibers having a 3.2 /spl mu/m core diameter and 125 /spl mu/m cladding. In a second method the tips were prepared by a wet chemical etching procedure.