Orbital angular momentum multiplication in plasmonic vortex cavities

Abstract

Orbital angular momentum of light is a core feature in photonics. Its confinement to surfaces using plasmonics has unlocked many phenomena and potential applications. Here, we introduce the reflection from structural boundaries as a new degree of freedom to generate and control plasmonic orbital angular momentum. We experimentally demonstrate plasmonic vortex cavities, generating a succession of vortex pulses with increasing topological charge as a function of time. We track the spatiotemporal dynamics of these angularly decelerating plasmon pulse train within the cavities for over 300 femtoseconds using time-resolved photoemission electron microscopy, showing that the angular momentum grows by multiples of the chiral order of the cavity. The introduction of this degree of freedom to tame orbital angular momentum delivered by plasmonic vortices could miniaturize pump probe–like quantum initialization schemes, increase the torque exerted by plasmonic tweezers, and potentially achieve vortex lattice cavities with dynamically evolving topology.

Dynamics of optical vortices in 2D materials

“…In most experiments that showed 2D optical vortices so far, the boundary conditions were designed for generating a specific vortex OAM at a specific location that remains constant in time (e.g., Refs. 21,22 ). In our experiment, we used the natural edges of the sample to show that vortex spatiotemporal dynamics can appear in arbitrary samples with only a single requirement -that the sample is optically mesoscopic.…”

Spin-orbit-locked hyperbolic polariton vortices carrying reconfigurable topological charges

“…Based on these principles, a plasmonic vortex has been explored to enhance the channel capacity of on-chip optical communication networks [36]. Plasmonic OAMs can selectively couple to the spin of light excitation, inducing spin-orbit interactions [37,38] and spin-controlled plasmonic phenomena, such as unidirectional routing [39], plasmonic vortex generation [29,30,40,41] and information detection, opening new opportunities for low-energy information processing and computing. Extending these explorations to the polaritonic regime in the mid-IR range is exciting on various fronts: (1) we can expect significantly reduced loss compared to their plasmonic counterparts; (2) mid-IR frequencies are of particular interest for on-chip communications and sensing, since several biomolecules have fingerprints in this range; (3) endowing phonon polaritons with these new degrees of freedom unlocks new forms of low-energy information transport and processing.…”

On‐Chip Plasmonic Vortex Interferometers

“…[ 5–8 ] Recently, plasmonic vortices [ 9–19 ] generated through the excitation of SPs with azimuthal‐dependent phase profiles e ilθ have attracted considerable attention due to their promise for on‐chip particle manipulation and information processing. [ 20–23 ] The parameters l and θ are respectively the topological charge and the azimuth angle. The two‐dimensional annular intensity distribution endows plasmonic vortices with a very compact SP path, which holds the promise for constructing further miniaturized plasmonic interferometers.…”

“…For Archimedes spiral-shaped long slit based plasmonic vortex lenses, the topological charge of plasmonic vortices coupled from different CPs cannot be independently designated. [16][17][18][19][20][21] In contrast, the slit resonator based plasmonic vortex lenses can introduce unidirectional coupler designs [24][25][26] or Archimedes spiral shaped arrangements [27][28][29] to delink the spin-dependency. As results, the topological charge of the generated plasmonic vortices under different CP incidences can be independently tailored, providing a route toward realizing the plasmonic spin-Hall effect.…”