Plasmonic apertures for THz QCL near-field imaging

In this paper we report on the fabrication and testing of sub-wavelength apertures surrounded by annular plasmonic structures, for use in near-field imaging with a QCL source. Both double corrugated structures and planarised designs have been tested, with the latter producing a spatially uniform far-field emission profile. Greatly increased transmission has been observed when using plasmonic apertures over standard plain apertures. Sub-wavelength resolution has been measured with a standard, near-field knife-edge test.