Abstract: Nano-rod and bow-tie antennas that are gold nano-antennas on dielectric material and the nano-rod antenna arrays are numerically studied by the finite difference time domain method in three dimensions.The light field that project on the antennas can be confined to a spot with subwavelength width (~λ/11),and the light intensity can be enhanced to 91 times the incident light in the near-field with the bow-tie antenna.The enhancement also exists in the antenna arrays.The highest enhancement of the light intensity at the bow-tie antenna gap can reach about 28000 times,and the localized field can be coupled to a nano-particle near the antenna gap.

Key words: near-field optics, surface plasmons, optical antenna