The optical transmission and distribution through a subwavelength slit on a tapered metallic substrate was investigated. By using a 45° tapered structure, 6 times larger transmission enhancement was achieved compared with a traditional metallic plate structure because of the asymmetric excited surface waves and the matching of propagation constants between the surface waves and slit waveguide. In addition, a focus beam was obtained by patterning surface corrugations in the exit plane. By tuning the period of the surface corrugations, we were able to adjust the focal length with a spot size smaller than the diffraction limit. The focal point can be kept about 0.6μm with a focal length from 0.5μm to 2.5μm for a grating period from 0.5μm to 0.6μm.
|Number of pages||8|
|Journal||Proceedings of SPIE - The International Society for Optical Engineering|
|State||Published - 2005|
|Event||Plasmonics: Metallic Nanostructures and Their Optical Properties III - San Diego, CA, United States|
Duration: 31 Jul 2005 → 3 Aug 2005
- Nano optics
- Subwavelength aperture