Temporally deuterogenic plasmonic vortices.

Over the past decade, orbital angular momentum has garnered considerable interest in the field of plasmonics owing to the emergence of surface-confined vortices, known as plasmonic vortices. Significant progress has been made in the generation and manipulation of plasmonic vortices, which broadly unveil the natures of plasmonic spin-orbit coupling and provide accessible means for light-matter interactions. However, traditional characterizations in the frequency domain miss some detailed information on the plasmonic vortex evolution process. Herein, an exotic spin-orbit coupling phenomenon is demonstrated. More specifically, we theoretically investigated and experimentally verified a temporally deuterogenic vortex mode, which can be observed only in the time domain and interferes destructively in the intensity field. The spatiotemporal evolution of this concomitant vortex can be tailored with different designs and incident beams. This work extends the fundamental understanding of plasmonic spin-orbit coupling and provides a unique optical force manipulation strategy, which may fuel plasmonic research and applications in the near future.