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 ~3 orders of magnitude more power throughput than a conventional square aperture with a similar near-field spot size of ~0.1λ 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.
© 2003 Optical Society of America
(050.1220) Diffraction and gratings : Apertures
(110.0180) Imaging systems : Microscopy
(120.7000) Instrumentation, measurement, and metrology : Transmission
(350.3950) Other areas of optics : Micro-optics
(350.5610) Other areas of optics : Radiation
Xiaolei Shi, Lambertus Hesselink, and Robert L. Thornton, "Ultrahigh light transmission through a C-shaped nanoaperture," Opt. Lett. 28, 1320-1322 (2003)