An analysis of the light field and intensity distribution within a double-layer thin-film stack coated on a prism is presented in this paper. The effect of the thickness and the refractive index of a sample is investigated in order to use the double-layer structure in near-field microscopy. The results show that the electric field and the light intensity increase appreciably under the resonance condition, leading to an enhanced evanescent wave on the top of the double-layer stack. The intensity of the enhanced evanescent wave can be maximised approximately by up to seven times if a thick sample of refractive index 1.38 is attacked on the top of the double-layer stack. This result is of significance when this enhanced evanescent wave is used as an effective illumination source for biological samples in laser-trapping near-field microscopy.
|Number of pages||5|
|Publication status||Published - 1 Dec 1998|