Mixing the Light Spin with Plasmon Orbit by Nonlinear Light-Matter Interaction in Gold

Abstract

Transformation of light carrying spin angular momentum (SAM) to optical field vortices carrying orbital angular momentum (OAM) has been of wide interest in recent years. The interactions between two optical fields, each carrying one of those degrees of freedom, and furthermore, the transfer of the resulting angular momentum product to matter are seldom discussed. Here, we measure the interaction between 3D light carrying axial SAM and 2D plasmon-polariton vortices carrying high-order transverse OAM. The interaction is mediated by two-photon absorption within a gold surface, imprinting the resulting angular-momentum mixing into matter by excitation of electrons that are photo-emitted into vacuum. Interestingly, the spatial distribution of the emitted electrons carries the signature of a subtraction of the spin from the orbit angular momenta. We show experimentally and theoretically that the absorptive nature of this interaction leads to both single and double photon-plasmon angular momentum mixing processes by one-and two-photon interactions. Our results demonstrate high order angular momenta light-matter interactions, provide a glimpse into specific electronic excitation routes, and may be applied in future electronic sources and coherent control.

Self-Trapping of Light Using the Pancharatnam-Berry Phase

“…Similar phenomena are also expected to occur in other systems, such as Bose-Einstein condensates or beams of charged particles under the action of a magnetic field, real or effective. With respect to basic physics, our work confirms the relevancy of liquid crystals as a platform for the investigation of angularmomentum exchange between light and matter in the nonlinear regime [66,67], including spin-to-orbital conversion and the generation of self-trapped structured beams. The selflocalization provides a novel platform to create reconfigurable all-optical devices like directional couplers, beam splitters, beam combiners, and so on, based on the Pancharatnam-Berry phase and in the absence of refractive index modulation.…”

Functional Meta Lenses for Compound Plasmonic Vortex Field Generation and Control

“…Surface Plasmon Polaritons (SPPs) are evanescent electromagnetic waves propagating along metaldielectric interfaces. In recent years, their ability to carry surface-confined orbital angular momentum (OAM) and form plasmonic vortices has been of wide interest [1][2][3][4][5][6][7]. Understanding and controlling such vortices opens the door towards a variety of applications.…”

“…As shown above, the addressed spiral depends on the handedness of the circularly polarized illumination. The resulting plasmonic field distribution recorded with TR-PEEM, considering the subtractive spin-orbit mixing [7],…”

Orbital angular momentum multiplication in plasmonic vortex cavities

“…This contrasts with reflection from typical gratings, which are nonlocal with respect to linear momentum and provide both an increase and decrease the linear momentum by the reciprocal vector of the grating. The snapshots show 5 and 15 azimuthal lobes imprinted into the photoemitted electrons due to the nonlinear mechanism of our technique [23]. The bottom insets show azimuthal and radial fitting of the diameter as well as the number of lobes in the main vortex signal.…”

“…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.Orbital angular momentum (OAM) of light has been of wide interest in recent years [1-6], laying the foundation for promising applications such as reshaping light-matter interactions [7,8] optical tweezing [9][10][11][12], optical communications [13-15] and quantum information processing [16]. The confinement of OAM to a surface enabled access and control to new physical phenomena [17,18] including linear spin-orbit conversion [19][20][21], orbit-orbit conversion [22] as well as nonlinear spin-orbit mixing [23]. Recent experimental access to the sub-cycle surface plasmon polaritons (SPP) dynamics [24][25][26] enabled the study of the dynamical evolution of a vortex [27] and direct determination of its angular momentum, as well as revealed the dynamics of plasmonic nanofocusing [28,29], thus raising the possibility of temporal OAM control.…”