Anisotropic Generation and Detection of Surface Plasmon Polaritons Using Near-Field Apertured Probes

Abstract

Most recent studies centered on light-matter interactions at the nanoscale rely on near-field microscopy. Despite this, few works have been reported to date regarding the anisotropic generation of surface plasmons polaritons on metallic surfaces. This phenomenon is attributed exclusively to scattering near-field probes. This work is dedicated to demonstrating that the anisotropic generation of surface plasmons polaritons is not exclusive to scattering probes. Using a near-field apertured probe, in collection mode, we demonstrate the generation and detection of such phenomenon. By analyzing the momentum components of the obtained near-field images, it is demonstrated that the detected signal is mostly composed of near-field components. Therefore, our approach reduces the contribution of propagating modes, consequently easing the interpretation of near-field images.

In-plane radiation pattern generated by large particles in dielectric substrates

“…As seen in figure 4(b), edge 1 radiated efficiently into the in-plane direction, while edges 2 and 3 were primarily responsible for the generation of surface plasmons on the surface of the flake. This was an expected result, as the Au flake is thick enough (∼70 nm) to support surface plasmons [18]. Edge 1 was parallel to the polarization, meaning it could not excite surface plasmons, so there were no interference lines parallel to this edge on the surface of the flake, see figure 4(b).…”

“…It was also interesting to find that there were some modes on the surface of the particle. We believe that these modes are surface plasmons due to the Au properties[18]. In particular, it is clear in figure2(b) that there is a peak surrounded by two lobes on the intensity at the top of the Au particle, see the red arrows.…”

“…The samples consisted of a set of crystalline Au structures (CAuS) fabricated by chemical reduction [18] and deposited by spin coating on a glass substrate. Our procedure consisted of three main steps: cleaning of the glass substrates, fabrication of a solution of CAuS in acetone, and spin coating of this solution onto the glass substrate.…”

“…An interesting alternative to PAs would be to use structures with dimensions larger than the excitation wavelength, which has not been reported to date. These structures can be fabricated by chemical reduction processes [18] that allow the deposition of a large number of structures, control of the size, and a large fabrication area.…”