In these days, the Journal of Opto-Electronic Advances published a new paper entitled as “Tailoring spatiotemporal dynamics of plasmonic vortices”
A plasmonic vortex is an optical field distribution with topological features formed by interfering surface plasmons, which enriches the class of vortex phenomena in nature. Due to their special orbital angular momentum feature in the evanescent field region, plasmonic vortices hold great promises for many cutting-edge applications, such as plasmonic tweezers for microparticle manipulations and on-chip quantum information processing. The generation methods and evolution dynamics of plasmonic vortices have thus elicited great research enthusiasm in the last decade, which have provided many insights into the nature of plasmonic vortex and rapidly promoted the related applications forward.
For plasmonic vortex generation, the most common method is constructing special couplers and utilizing the design degrees of freedoms of propagation phase and geometric phase to convert circularly polarized light carrying spin angular momentum into on-chip plasmonic vortex. Despite the sole or combined use of propagation and geometric phase can all achieve plasmonic vortex of target topological charge, the actual differences of their spatiotemporal dynamics have remained unexplored. For characterization methods, the currently used photoemission electron microscopy and nonlinear near-field optical microscopy are limited by the probing principle and optical systems, thus can hardly obtain the exact evolution dynamics. The research documented by this article mainly focused on the objective characterization of plasmonic vortex and the subjectively tailoring of its spatiotemporal dynamics for specific applications has not been achieved. The research group from Tianjin University, Guilin University of Electronic Technology and authors of this article propose a new method to tailor the spatiotemporal dynamics of plasmonic vortices. It is demonstrated that the plasmonic vortices with the same topological charge can be endowed with distinct spatiotemporal dynamics by simply changing the coupler design (Fig 1). The full amplitude and phase information of surface plasmons fields and the exact evolution dynamics with ultrahigh temporal resolution were directly obtained based on a near-field scanning terahertz microscopy.
