Optical resonance of nanometer scale bow-tie antenna and bow-tie shaped aperture antenna

In this paper, the nanometer scale bow-tie antenna and its geometrically complementary bow-tie shaped aperture antenna are proposed and discussed focusing on their optical resonance characteristics. To demonstrate such structures, the finite integration technique is developed in broad band calculations especially in the visible and infrared region. Characterized by surface plasmon resonance, localized strong field are found at the separation gap of the bow-tie antenna, thus providing satisfying near-field confinement and enhancement. In addition, the resonant properties depending on the effects of the geometrical parameters of length and gap distance are systematical studied. Furthermore, comparison of the performances between the two structures is presented for the first time. This investigation can be applied to near-field optical detection or imaging, scanning probe microscopy, lithography and optical manipulation, which has a promising prospect for nanoantennas.