Selective Excitation of Plasmon Resonances of Single Au Triangles by Polarization-Dependent Light Excitation

Abstract

The plasmonic properties of single Au triangular nanoprisms are investigated using photoemission electron microscopy with particular emphasis on polarization dependence. Two localized surface plasmon resonances (LSPRs) are studied, namely, the in-plane dipolar and quadrupolar plasmon excitations. Experimental maps of the near-field spatial distribution upon polarization and wavelength of the exciting field are interpreted in the framework of a group theory description and finite difference time domain simulations. This work demonstrates the selective excitations, by lifting of degeneracy, of the different LSPR eigenmodes at the single object level and opens ways for the active control of the angular radiation patterns of optical nanoantennas. This approach is general and applies to any nano-object, whatever its initial shape symmetry.

On the absorption and electromagnetic field spectral shifts in plasmonic nanotriangle arrays

“…Resonances at = 750 nm and = 800 nm corresponds to the dipolar contributions; the intensity maps in Figs. 1(d) and 1(e) shows that the normalized electric field resonances are located close to the corners, in agreement with previous work [13]. The logarithms of the magnitude of the electric field enhancement at the dipolar resonance (1.3 for x-polarized and 1.6 for y-polarized) are larger than those obtained for the quadrupolar resonance (0.8 for xpolarized and 0.9 for y-polarized).…”

Plasmonic eigenmodes in individual and bow-tie graphene nanotriangles

“…A one-to-one correspondence is evident and whenever the spectrum in Figure 1 suggests a pair of degenerate states, the corresponding modes in Figure 2 support that they are indeed pairs of orthogonal and degenerate states. The energy degeneracies exhibited here are a direct consequence of the symmetries of the considered nanostructure, as required by group theory57.…”

Engineering the emission of light from a scanning tunneling microscope using the plasmonic modes of a nanoparticle

“…It is these electric near-field distributions that will be used in one of the approaches proposed below to predict the intensity and angular distribution of the emitted light as a function of the tip excitation position on the NP. Due to the small NP size, we may restrict ourselves to the dipolar resonances since higher-order multipole resonances [42][43][44] are comparatively much less pronounced, and occur above 2.4 eV according to our calculations.…”

“…2(e)]. The nanotriangle supports four basic dipolar excitations: a vertical dipole perpendicular to the substrate, and three degenerate in-plane dipolar modes [42,43], which can be expressed as p x =ê x p || , and…”