Abstract-Terahertz beam focusing based on plasmonic waveguide scattering

Yasuaki Monnai¹, Kristian Altmann², Christian Jansen², Martin Koch², Hartmut Hillmer³, and Hiroyuki Shinoda¹

¹Department of Information Physics and Computing, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
²Department of Physics, Philipps University of Marburg, Renthof 5, 35032 Marburg, Germany
³Institute of Nanostructure Technologies and Analytics, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany

http://apl.aip.org/resource/1/applab/v101/i15/p151116_s1

We demonstrate free-space focusing of terahertz (THz) radiation by scattering plasmonic surface-waves into the air. We use a grating of shallow holes which contains non-equidistant defects which act as scattering centers. The scattering occurs with defined phase delays such that the waves emitted in free-space interfere constructively to form a focus above the waveguide surface. In contrast to conventional lenses, this structure does not require any free-space on its backside and has great potential for integrated THz optics.

© 2012 American Institute of Physics