Ultrahigh light transmission through a C-shaped nanoaperture

Optical resolution beyond the diffraction limit can be achieved by use of a metallic nanoaperture in a near-field optical system. Conventional nanoapertures have very low power throughput. Using a numerical finite-difference time domain method, we discovered a unique C-shaped aperture that provides similar to3 orders of magnitude more power throughput than a conventional square aperture with a similar near-field spot size of similar to0.1lambda Microwave experiments at 6 GHz quantitatively confirmed the simulated transmission enhancement. The high transmission of the C-aperture-or one of the related shapes-is linked to both a propagation mode in the aperture and local surface plasmons. (C) 2003 Optical Society of America.