The first demonstration, to our knowledge, of near-field imaging using subwavelength plasmonic apertures with a terahertz quantum cascade laser source is presented. “Bull’s-eye” apertures, featuring subwavelength circular apertures flanked by periodic annular corrugations were created using a novel fabrication method. A fivefold increase in intensity was observed for plasmonic apertures over plain apertures of the same diameter. Detailed studies of the transmitted beam profiles were undertaken for apertures with both planarized and corrugated exit facets, with the former producing spatially uniform intensity profiles and subwavelength spatial resolution. Finally, a proof-of-concept imaging experiment is presented, where an inhomogeneous pharmaceutical drug coating is investigated.
© 2011 Optical Society of America
Original Manuscript: February 22, 2011
Revised Manuscript: May 25, 2011
Manuscript Accepted: May 25, 2011
Published: June 20, 2011
Vol. 6, Iss. 8 Virtual Journal for Biomedical Optics
Adam J. Baragwanath, Joshua R. Freeman, Andrew J. Gallant, J. Axel Zeitler, Harvey E. Beere, David A. Ritchie, and J. Martyn Chamberlain, "Terahertz near-field imaging using subwavelength plasmonic apertures and a quantum cascade laser source," Opt. Lett. 36, 2393-2395 (2011)