[OPTICAL REVIEW Vol. 6, No. 3 (1999) 261-267]
Interaction of Near-Field Light with Ordered Polystyrene Spheres: Experimental Studies*
Masanobu HARAGUCHI,1 Teruyuki NAKAI,1 Akihiko SHINYA,1 Toshihiro OKAMOTO,1 Masuo FUKUI,1 Takao KODA,2 Ryoko SHIMADA2 and Kenji TAKEDA3
1Department of Optical Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1, Minamijosanjima, Tokushima, 770-8506 Japan, 2Department of Mathematics and Physics, Faculty of Science, Japan Women's University, 2-8-1, Mejirodai, Bunkyoku, Tokyo, 112-8681 Japan, 3Tsukuba Research Laboratory, Japan Synthetic Rubber Co., Ltd., 25, Misachigaoka, Tsukuba, Ibaraki, 305-0841 Japan
(Recieved December 7, 1998; Accepted January 13, 1999)
We have experimentally observed the interaction of near-field light excited in a total internal reflection geometry with a periodic two-dimensional array of polystyrene spheres. The angular- and frequency-scanned attenuated-total-reflection (ATR) method was employed to observe the interaction. ATR spectra indicate that there is an easy axis and a difficult axis for the light propagation. When light is incident toward the easy axis, resonant dips appear in the ATR spectra. The experimental results were compared with those obtained by finite-difference time-domain analysis. The numerical results obtained by this method are able to explain a part of the experimental ones. Parts of the dips in the ATR spectra were considered to stem from propagating and whispering-gallery (WG) modes. That is, the propagation of the WG-modes over several spheres may enhance the coupling between the spheres and the incident light, and consequently may induce resonant structures in the ATR spectra.
Key words : near-field, ordered polystyrene spheres, attenuated total reflection, photonic crystal, evanescent wave, Whispering-Gallery mode, light propagation