Finite-difference time-domain analysis of the interaction of gaussian evanescent light with a single dielectric sphere or ordered dielectric spheres

The interaction of gaussian evanescent light with a single dielectric spher e or ordered dielectric spheres in an attenuated total reflection (ATR) geo metry was analyzed by the finite-difference time-domain method. Various asp ects of this interaction were investigated in terms of spatial visualizatio ns of light intensity, reflectance vs. wavelength characteristics, the tran sient behavior of reflectances, and so forth. In the case of a single spher e, it was evident that the whispering gallery mode can be excited in ATR ge ometries, but such excitation cannot be easily confirmed only through the o bservation of wavelength-scanned ATR spectra. In the case of a closely pack ed two-dimensional array of dielectric spheres, it was found that an easy a xis and also a difficult axis for light propagation exist.