[OPTICAL REVIEW Vol. 6, No. 3 (1999) 211-214]

Field Enhancement by a Metallic Sphere on Dielectric Substrates

Takayuki OKAMOTO and Ichirou YAMAGUCHI

Optical Engineering Laboratory, The Institute of Physical and Chemical Research (Riken), 2-1, Hirosawa, Wako, Saitama, 351-0198 Japan

(Received December 7, 1998; accepted January 21, 1999)

We calculate the scattered local field around a small gold sphere on dielectric substrates which is illuminated by a collimated monochromatic beam. The numerical results show the field between the sphere and the substrate is much enhanced when the sphere is illuminated by a p-polarized beam. The enhanced area is very localized between the sphere and the substrate and the diameter of the enhanced area on the surface of the substrate is one fifth of the sphere diameter. The field increases as the gap distance decreases or as the refractive index of the substrate increases.

Key words : light scattering, field enhancement, metal particle, local plasmon