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We perform momentum mapping of the Raman scattering of individual single-walled carbon nanotubes (SWNTs) or thin ropes of SWNTs enhanced by surface plasmons sustained by either a linear chain of nanoantennas or flower-shaped nanoparticles. The momentum spectroscopy of Raman scattering of the carbon nanotube (CNT) demonstrates the direct verification of momentum selection rules and identifies the characteristic bands of the molecules or the nanomaterials under scrutiny. The characteristic vibrational signatures of the D, G−, and G bands provide an isotropic response in k-space irrespective of the arrangement of the enhancing platform. However, other dispersive or double resonance bands, such as D−, D+, D′, M, and iTOLA bands appear as a dipolar emission oriented towards the long axis of the CNT regardless of the CNT orientation but strongly depend on the patterning of enhancement of the electromagnetic field.

A method is presented for the characterization of locally enhanced fields at laser-irradiated metal nanostructures. Excitation with 120 fs laser pulses gives rise to photoluminescence mediated by two-photon absorption. A metal tip used to locally scatter the photoluminescence renders a map of regions with high field strengths. Near-field photoluminescence images of particle clusters reveal the dipole nature of the electromagnetic field surrounding the particles. Spectra acquired with and without the presence of the tip show no significant shift of the surface plasmon resonance of the particle clusters, confirming that the tip acts as a passive probe.

Longitudinal fields created in strongly focused laser beams are investigated by near-field optical microscopy. Sharp metallic and dielectric tips are raster scanned through the focus of these modes. It is found that regardless of the tip material, the signal scattered by the tip is a measure for the strength of the local longitudinal field. A surprising contrast reversal is observed between the images obtained with a metallic tip and the images obtained with a dielectric tip. The contrast reversal originates from a non-negligible tip–sample interaction.

Active control of surface plasmon polaritons (SPPs) by optical isomerization of an azobenzene polymer film is proposed and demonstrated in this letter. A tightly focused 532 nm laser beam was used to change the wave number of the SPPs and a separate unpolarized light source was employed to erase the change, forming one cycle of the control. The largest change of the SPPs wave number obtained in the experiments is about 0.0382K0 in the case of 54 nm thickness azo-polymer film. Validity of this method is confirmed by consistence between theoretical and experimental results.