Hollow-pyramid near-field probes. (a) SEM image of the pyramidal tip mounted on the cantilever. A zoom of the entire pyramid is shown in the inset. (b) Further zoom on the apex. The aperture diameter is about 120 nm.
Schematics of the experimental setup for illumination mode SNOM. WP: half-wavelength waveplate, DBS: dichroic beam-splitter, PMT: photomultiplier tube.
(a) Interferometric second-order autocorrelation of ultrashort pulses transmitted by a 100-nm hollow-pyramid probe. (b) Polar graph of the emission pattern of near-field excitation obtained by an oriented fluorescent polymer thin film below the tip. The double arrow indicates the orientation of the incident electric field polarization on the hollow probe.
Schematics of the experimental setup for collection mode SNOM combined to a confocal microscope. The confocal setup works in a back-reflection scheme on the back side of the sample, while the SNOM probe collects light emerging from the front side. BS: beam splitter. PMT: photomultiplier tube. SPAD: single photon counting avalanche diode unit. The size of the SPAD active area serves as a spatial filter.
Metal projection pattern: (a) topography and (b) SH SNOM image. The solid circle indicates a SH emitting triangle, while the dashed one indicates a nonemitting structure. (c) Line profile taken from a zoomed scan within the SH image. R is the resolution and C is the contrast (signal to background ratio). Inset: single hexagonal pattern from which the line profile is taken (dashed line).
Polarization-dependent SHG maps from the same metal projection hexagonal pattern. The linear light polarization is indicated by the arrows. Solid circles indicate strongly emitting structures, dashed circles point out weakly emitting triangles, and dotted ones show structures with almost no emission.
Nanorods: [(a) and (d)] topography, [(b) and (e)] FW transmission, and [(c) and (f)] SH emission SNOM images. [(a)–(c)] Incident light is polarized parallel to the minor axis. [(d)–(f)] Polarization is oriented parallel to major axis.
Comparison between TPPL and SHG emission. (a) TPPL image of a single rod nanoparticle (transverse dimensions: ). (b) SHG emission map from the same particle. (c) Line profiles taken from both images (at dotted lines). Excitation light is polarized along the major axis (see arrows).
(a) Topography, (b) far-field TPPL, and (c) near-field TPPL maps of a gold coupled-nanorod system. The position of the antenna is depicted by the ellipses. (d) Line profile [dotted line in (c)] clearly shows three emission spots corresponding to both nanorods and to the gap between them. Excitation light is polarized along the antenna axis (see arrow).
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