Polarization effects in apertureless scanning near-field optical microscopy: an experimental study

Strong electric-field enhancements at the apex of a tungsten tip illuminate d by an external light source were recently predicted theoretically. We pre sent an experimental study of the dependence of this effect on the polariza tion angle of the incident light. It is shown that the intensity of the lig ht scattered by the tungsten tip of an apertureless scanning near-field opt ical microscope is 2 orders of magnitude higher when the incident light is p polarized than when it is s polarized. This experimental result is in goo d agreement with theoretical predictions and provides an easy way to test t he quality of the tips. (C) 1999 Optical Society of America OCIS codes: 120 .5820, 170.5810, 260.2110, 260.5430.