Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 64: Plasmonics and nanooptics III

O 64.10: Talk

Thursday, March 29, 2012, 12:45–13:00, MA 005

Investigation of mid-infrared s-SNOM subsurface imaging on topography-free samples — •Andreas Engelhardt, Benedikt Hauer, and Thomas Taubner — I. Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074 Aachen, Germany

Scattering-type scanning near-field optical microscopy (s-SNOM) provides optical information of a sample with a nanoscale-resolution in the order of the probing tip radius (∼ 30 nm) which allows for material-specific imaging and even spectroscopy on the nanoscale. Optical coupling of the probe with nanoscale objects also occurs through thin cover layers of low refracting materials enabling the detection of objects underneath the surface [1].

We demonstrate subsurface s-SNOM imaging of metallic nanostructures with mid-infrared light through thin (30−100 nm) and flat dielectric layers. The latter do not reveal the geometry of the structures in their surface topography, thus topography artifacts are avoided. We observe that the visibility of the buried objects improves with increasing oscillation amplitude of the probe due to a better signal-to-noise ratio, however at the cost of contrast loss. The study provides basic experimental data for the theoretical development of a powerful s-SNOM based nondestructive nano-tomography characterization method [2].

[1] T. Taubner et al., Optics Express, 13, 8893 (2005)

[2] J. Sun et al, APL, 95, 121108 (2009)