[OPTICAL REVIEW Vol. 6, No. 3 (1999) 215-223]

Finite-Difference Time-Domain Analysis of the Interaction of Gaussian Evanescent Light with a Single Dielectric Sphere or Ordered Dielectric Spheres*

Akihiko SHINYA and Masuo FUKUI

Department of Optical Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1, Minamijosanjima, Tokushima, 770-8506 Japan

(Received December 7, 1998; Accepted January 13, 1999)

The interaction of gaussian evanescent light with a single dielectric sphere or ordered dielectric spheres in an attenuated total reflection (ATR) geometry was analyzed by the finite-difference time-domain method. Various aspects of this interaction were investigated in terms of spatial visualizations of light intensity, reflectance vs. wavelength characteristics, the transient behavior of reflectances, and so forth. In the case of a single sphere, it was evident that the whispering gallery mode can be excited in ATR geometries, but such excitation cannot be easily confirmed only through the observation of wavelength-scanned ATR spectra. In the case of a closely packed two-dimensional array of dielectric spheres, it was found that an easy axis and also a difficult axis for light propagation exist.

Key words : gaussian evanescent light, visible light, whispering gallery modes, single sphere, ordered spheres, ATR geometry