Asymmetric generation and detection of surface plasmons polaritons using near-field aperture probes

In recent years, the generation and detection of surface plasmons polaritons (SPPs) using near-field microscopy probes has become one of the most important research areas. Actually, nowadays most of the light-matter interactions studies rely on this technique. Though, few works have been reported to the date regarding the asymmetric generation of SPPs on metallic surfaces. Moreover, the asymmetric generation of SPPs is attributed exclusively to scattering near-field probes. With this in mind, this work is dedicated to demonstrate that the asymmetric generation of SPPs is not exclusive of such probes. In fact, it is shown that near-field aperture probes in collection mode can also generate and detect such a phenomenon. In addition, by analyzing the momentum components of the near-field images, it was demonstrated that the observed interactions are the result of the interference between SPPs of different momenta, confirming existing reports.