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[摘要]：We investigated the field enhancement properties of optical resonant Archimedean spiral antennas by using a finite difference time domain method. Due to the spiral structure, the antennas show a circular dichroism in the electric field enhancement, especially for a large turning angle. A large magnetic field enhancement is also obtained with a confinement in the nanometer size. When the turning angle equals p for a linearly polarized incident beam, the polarization of the enhanced field in the spiral antenna can be perpendicular to the incident polarization with a similar enhancement factor to the optical resonant dipole antennas. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3643270] |
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