We demonstrate an experimental result that shows the phase singularity of surface plasmon waves generated by the direct transform of optical vortices at normal incidence focused on a structureless metal surface. The near-field two-dimensional intensity distribution near the focal plane is experimentally examined by using near-field scanning optical microscopy and shows a good agreement with the finite-difference time-domain simulation result. The experimental realization demonstrates a potential of the proposed excitation scheme to be reconfigured locally with advantages over structures milled into optically thick metallic films for plasmonics applications involving plasmonic vortices.
© 2011 Optical Society of America
Diffraction and Gratings
Original Manuscript: May 3, 2011
Manuscript Accepted: July 27, 2011
Published: August 15, 2011
P. S. Tan, G. H. Yuan, Q. Wang, N. Zhang, D. H. Zhang, and X.-C. Yuan, "Phase singularity of surface plasmon polaritons generated by optical vortices," Opt. Lett. 36, 3287-3289 (2011)