We numerically demonstrate that properly designed plasmonic covers can be used to enhance the performance of near-field scanning optical microscopy (NSOM) systems based on the employment of apertureless metallic tip probes. The covering material, exhibiting a near-zero value of the real permittivity at the working frequency, is designed in such a way to dramatically reduce the undesired scattering due to the strongly plasmonic behavior of the tip. Though the light scattering by the tip end is necessary for the correct operation of NSOMs, the additional scattering due to the whole probe affects the signal-to-noise ratio and thus the resolution of the acquired image. By covering the whole probe but not the very tip, we show that unwanted scattering can be effectively reduced. A realistic setup, working at mid-IR frequencies and employing silicon carbide covers, has been designed and simulated to confirm the effectiveness of the proposed approach.
© 2011 Optical Society of America
Original Manuscript: October 29, 2010
Revised Manuscript: November 30, 2010
Manuscript Accepted: December 6, 2010
Published: January 11, 2011
Vol. 6, Iss. 2 Virtual Journal for Biomedical Optics
Filiberto Bilotti, Simone Tricarico, Francesco Pierini, and Lucio Vegni, "Cloaking apertureless near-field scanning optical microscopy tips," Opt. Lett. 36, 211-213 (2011)