We investigate the effect of defects in the metal-coating layer of a scanning near-field optical microscopy (SNOM) probe on the coupling of polarization modes using rigorous electromagnetic modeling tools. Because of practical limitations, we study an ensemble of simple defects to identify important trends and then extrapolate these results to more realistic structures. We find that a probe with many random defects will produce a small but significant coupling of energy between a linearly polarized input mode and a radial/longitudinal polarization mode, which is known to produce a strongly localized emitted optical field and is desirable for SNOM applications.
© 2006 Optical Society of America
Original Manuscript: July 19, 2005
Revised Manuscript: October 12, 2005
Manuscript Accepted: November 2, 2005
Vol. 1, Iss. 6 Virtual Journal for Biomedical Optics
Wataru Nakagawa, Luciana Vaccaro, and Hans Peter Herzig, "Analysis of mode coupling due to spherical defects in ideal fully metal-coated scanning near-field optical microscopy probes," J. Opt. Soc. Am. A 23, 1096-1105 (2006)