Probing and Imaging Photonic Spin-Orbit Interactions in Nanostructures

Photonic spin-orbit interactions (PSOIs) in nanostructures have attracted much interest in nanophotonics, which provide a new paradigm to enhance light-matter interactions and engineer the wavefronts of light on demand at the nanoscale. Many striking phenomena and functionalities, such as the photonic (quantum) spin-Hall effect and the spin-vortex conversion, have been demonstrated. Besides their underlying physics and manifestations, the experimental probing and imaging of PSOIs are also of great importance and highly demanded in not only the fundamental research but also the development of emerging PSOI technologies. Hence, in this review, the state-of-the-art studies on the experimental observations and detections of PSOIs are systematically reviewed, including both the far-field and near-field methods. The respective advantages and difficulties of each method are stated and analyzed. The perspectives in probing PSOIs are also discussed.