Routing a Chiral Raman Signal Based on Spin-Orbit Interaction of Light.

Spontaneous Raman scattering is a second-order perturbation process with two photons linking the internal structures of the matter. The frequency-shifted Raman peaks are sharp and carry rich information about the internal structures. However, encoding and manipulating this information have been barely explored up to now. Here, we report the high-fidelity routing of a chiral Raman signal into propagating surface plasmon polaritons along a silver nanowire based on spin-orbit interaction of light. A directionality up to 91.5±0.5% is achieved and can be quantitatively controlled by tuning the polarization of the incident laser and the position of excitation. The deterministic routing of the Raman signal is sensitively dependent on the local spin density of the plasmon field and the polarization of the Raman modes. This study extends the spin-orbit interaction of light to the Raman scattering regime and proposes a new perspective for the remote readout of local optical chirality, helicity-related directional sorting, and quantum information processing.