Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 42: Plasmonics and Nanooptics III: Infrared Microscopy

O 42.2: Talk

Tuesday, March 8, 2016, 14:15–14:30, H4

Experimental investigation of the depth-dependent near-field coupling in subsurface s-SNOM imaging. — •Mike Prämassing, Martin Lewin, and Thomas Taubner — Institute of Physics (IA) RWTH Aachen

Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) is based on a laser-illuminated metal-coated tip being scanned over the sample. Due to the localized tip sample interaction, the optical properties of the sample can be analysed on the nm-scale. Since the tip probes high spatial frequencies, s-SNOM is capable of imaging buried structures via evanescent waves [1]. We could distinguish between amorphous and crystalline regions of AgInSbTe even below 100 nm of capping layer [2]. The found complex material contrasts can be explained by theoretical calculations taking into account the layered structure of the sample [3]. At the sample surface, the tip predominantly probes spatial frequencies in the range of the inverse tip radius. Here we investigate the tip-sample-coupling for different burying depth and spatial frequencies. High quality gold gratings are employed to produce well defined spatial frequencies. The Depth dependence of the coupling of the tip to these spatial frequencies is investigated by measuring the gratings buried below PMMA layers of varying thickness.

[1] Taubner et al., Opt. Express 13, 8893 (2005)
[2] Lewin et al., Appl. Phys. Lett., 107, 151902 (2015)
[3] Hauer et al., Opt Expr. 20, 13173 (2012)